From 3488bbecacd50676cd512b1c7cdc3b4e4764acb6 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Fri, 29 Mar 2024 14:04:16 -0400
Subject: [PATCH 01/21] Support Arbitrary callbacks - Allow no output callback
 - Add global set_props - Fix side update pattern ids

---
 .pylintrc                                     |  2 +-
 dash/__init__.py                              |  2 +-
 dash/_callback.py                             | 56 +++++++++++++------
 dash/_callback_context.py                     | 16 ++++++
 dash/_utils.py                                |  8 ++-
 dash/dash-renderer/src/actions/callbacks.ts   | 54 +++++++++++-------
 .../dash-renderer/src/actions/dependencies.js | 53 ++++++++++++------
 dash/dash-renderer/src/types/callbacks.ts     |  1 +
 dash/dash.py                                  | 31 +++++++---
 dash/long_callback/_proxy_set_props.py        |  7 +++
 dash/long_callback/managers/__init__.py       |  7 +++
 dash/long_callback/managers/celery_manager.py | 17 ++++++
 .../managers/diskcache_manager.py             | 15 +++++
 13 files changed, 204 insertions(+), 65 deletions(-)
 create mode 100644 dash/long_callback/_proxy_set_props.py

diff --git a/.pylintrc b/.pylintrc
index 554f953b8e..db7fac560e 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -426,7 +426,7 @@ max-public-methods=40
 max-returns=6
 
 # Maximum number of statements in function / method body
-max-statements=50
+max-statements=75
 
 # Minimum number of public methods for a class (see R0903).
 min-public-methods=2
diff --git a/dash/__init__.py b/dash/__init__.py
index f46d6f77e1..8f740e35ba 100644
--- a/dash/__init__.py
+++ b/dash/__init__.py
@@ -18,7 +18,7 @@
 from . import html  # noqa: F401,E402
 from . import dash_table  # noqa: F401,E402
 from .version import __version__  # noqa: F401,E402
-from ._callback_context import callback_context  # noqa: F401,E402
+from ._callback_context import callback_context, set_props  # noqa: F401,E402
 from ._callback import callback, clientside_callback  # noqa: F401,E402
 from ._get_app import get_app  # noqa: F401,E402
 from ._get_paths import (  # noqa: F401,E402
diff --git a/dash/_callback.py b/dash/_callback.py
index d2fa15742d..7b6f305038 100644
--- a/dash/_callback.py
+++ b/dash/_callback.py
@@ -226,6 +226,7 @@ def insert_callback(
     manager=None,
     running=None,
     dynamic_creator=False,
+    no_output=False,
 ):
     if prevent_initial_call is None:
         prevent_initial_call = config_prevent_initial_callbacks
@@ -234,7 +235,7 @@ def insert_callback(
         output, prevent_initial_call, config_prevent_initial_callbacks
     )
 
-    callback_id = create_callback_id(output, inputs)
+    callback_id = create_callback_id(output, inputs, no_output)
     callback_spec = {
         "output": callback_id,
         "inputs": [c.to_dict() for c in inputs],
@@ -248,6 +249,7 @@ def insert_callback(
             "interval": long["interval"],
         },
         "dynamic_creator": dynamic_creator,
+        "no_output": no_output,
     }
     if running:
         callback_spec["running"] = running
@@ -262,6 +264,7 @@ def insert_callback(
         "raw_inputs": inputs,
         "manager": manager,
         "allow_dynamic_callbacks": dynamic_creator,
+        "no_output": no_output,
     }
     callback_list.append(callback_spec)
 
@@ -283,10 +286,12 @@ def register_callback(  # pylint: disable=R0914
         # Insert callback with scalar (non-multi) Output
         insert_output = output
         multi = False
+        no_output = False
     else:
         # Insert callback as multi Output
         insert_output = flatten_grouping(output)
         multi = True
+        no_output = len(output) == 0
 
     long = _kwargs.get("long")
     manager = _kwargs.get("manager")
@@ -315,6 +320,7 @@ def register_callback(  # pylint: disable=R0914
         manager=manager,
         dynamic_creator=allow_dynamic_callbacks,
         running=running,
+        no_output=no_output,
     )
 
     # pylint: disable=too-many-locals
@@ -333,7 +339,8 @@ def add_context(*args, **kwargs):
             app_callback_manager = kwargs.pop("long_callback_manager", None)
             callback_ctx = kwargs.pop("callback_context", {})
             callback_manager = long and long.get("manager", app_callback_manager)
-            _validate.validate_output_spec(insert_output, output_spec, Output)
+            if not no_output:
+                _validate.validate_output_spec(insert_output, output_spec, Output)
 
             context_value.set(callback_ctx)
 
@@ -443,6 +450,9 @@ def add_context(*args, **kwargs):
                         NoUpdate() if NoUpdate.is_no_update(r) else r
                         for r in output_value
                     ]
+                updated_props = callback_manager.get_updated_props(cache_key)
+                if len(updated_props) > 0:
+                    response["sideUpdate"] = updated_props
 
                 if output_value is callback_manager.UNDEFINED:
                     return to_json(response)
@@ -452,7 +462,10 @@ def add_context(*args, **kwargs):
             if NoUpdate.is_no_update(output_value):
                 raise PreventUpdate
 
-            if not multi:
+            if no_output:
+                output_value = []
+                flat_output_values = []
+            elif not multi:
                 output_value, output_spec = [output_value], [output_spec]
                 flat_output_values = output_value
             else:
@@ -464,23 +477,30 @@ def add_context(*args, **kwargs):
                 # Flatten grouping and validate grouping structure
                 flat_output_values = flatten_grouping(output_value, output)
 
-            _validate.validate_multi_return(
-                output_spec, flat_output_values, callback_id
-            )
-
             component_ids = collections.defaultdict(dict)
             has_update = False
-            for val, spec in zip(flat_output_values, output_spec):
-                if isinstance(val, NoUpdate):
-                    continue
-                for vali, speci in (
-                    zip(val, spec) if isinstance(spec, list) else [[val, spec]]
-                ):
-                    if not isinstance(vali, NoUpdate):
-                        has_update = True
-                        id_str = stringify_id(speci["id"])
-                        prop = clean_property_name(speci["property"])
-                        component_ids[id_str][prop] = vali
+            if not no_output:
+                _validate.validate_multi_return(
+                    output_spec, flat_output_values, callback_id
+                )
+
+                for val, spec in zip(flat_output_values, output_spec):
+                    if isinstance(val, NoUpdate):
+                        continue
+                    for vali, speci in (
+                        zip(val, spec) if isinstance(spec, list) else [[val, spec]]
+                    ):
+                        if not isinstance(vali, NoUpdate):
+                            has_update = True
+                            id_str = stringify_id(speci["id"])
+                            prop = clean_property_name(speci["property"])
+                            component_ids[id_str][prop] = vali
+
+            if not long:
+                side_update = dict(callback_ctx.updated_props)
+                if len(side_update) > 0:
+                    has_update = True
+                    response["sideUpdate"] = side_update
 
             if not has_update:
                 raise PreventUpdate
diff --git a/dash/_callback_context.py b/dash/_callback_context.py
index 7638d0a860..db82d5aaee 100644
--- a/dash/_callback_context.py
+++ b/dash/_callback_context.py
@@ -2,6 +2,7 @@
 import warnings
 import json
 import contextvars
+import typing
 
 import flask
 
@@ -247,5 +248,20 @@ def using_outputs_grouping(self):
     def timing_information(self):
         return getattr(flask.g, "timing_information", {})
 
+    @has_context
+    def set_props(self, component_id: typing.Union[str, dict], props: dict):
+        ctx_value = _get_context_value()
+        if isinstance(component_id, dict):
+            ctx_value.updated_props[json.dumps(component_id)] = props
+        else:
+            ctx_value.updated_props[component_id] = props
+
 
 callback_context = CallbackContext()
+
+
+def set_props(component_id: typing.Union[str, dict], props: dict):
+    """
+    Set the props for a component not included in the callback outputs.
+    """
+    callback_context.set_props(component_id, props)
diff --git a/dash/_utils.py b/dash/_utils.py
index 5b3b1d62e1..648c27e040 100644
--- a/dash/_utils.py
+++ b/dash/_utils.py
@@ -131,7 +131,7 @@ def first(self, *names):
             return next(iter(self), {})
 
 
-def create_callback_id(output, inputs):
+def create_callback_id(output, inputs, no_output=False):
     # A single dot within a dict id key or value is OK
     # but in case of multiple dots together escape each dot
     # with `\` so we don't mistake it for multi-outputs
@@ -149,6 +149,12 @@ def _concat(x):
             _id += f"@{hashed_inputs}"
         return _id
 
+    if no_output:
+        # No output will hash the inputs.
+        return hashlib.sha256(
+            ".".join(str(x) for x in inputs).encode("utf-8")
+        ).hexdigest()
+
     if isinstance(output, (list, tuple)):
         return ".." + "...".join(_concat(x) for x in output) + ".."
 
diff --git a/dash/dash-renderer/src/actions/callbacks.ts b/dash/dash-renderer/src/actions/callbacks.ts
index 68320568e5..845fcc7eee 100644
--- a/dash/dash-renderer/src/actions/callbacks.ts
+++ b/dash/dash-renderer/src/actions/callbacks.ts
@@ -324,19 +324,37 @@ async function handleClientside(
     return result;
 }
 
-function sideUpdate(outputs: any, dispatch: any, paths: any) {
-    toPairs(outputs).forEach(([id, value]) => {
-        const [componentId, propName] = id.split('.');
-        const componentPath = paths.strs[componentId];
+function updateComponent(component_id: any, props: any) {
+    return function (dispatch: any, getState: any) {
+        const paths = getState().paths;
+        const componentPath = getPath(paths, component_id);
         dispatch(
             updateProps({
-                props: {[propName]: value},
+                props,
                 itempath: componentPath
             })
         );
-        dispatch(
-            notifyObservers({id: componentId, props: {[propName]: value}})
-        );
+        dispatch(notifyObservers({id: component_id, props}));
+    };
+}
+
+function sideUpdate(outputs: any, dispatch: any) {
+    toPairs(outputs).forEach(([id, value]) => {
+        let componentId, propName;
+        if (id.includes('.')) {
+            [componentId, propName] = id.split('.');
+            if (componentId.startsWith('{')) {
+                componentId = JSON.parse(componentId);
+            }
+            dispatch(updateComponent(componentId, {[propName]: value}));
+        } else {
+            if (id.startsWith('{')) {
+                componentId = JSON.parse(id);
+            } else {
+                componentId = id;
+            }
+            dispatch(updateComponent(componentId, value));
+        }
     });
 }
 
@@ -345,7 +363,6 @@ function handleServerside(
     hooks: any,
     config: any,
     payload: any,
-    paths: any,
     long: LongCallbackInfo | undefined,
     additionalArgs: [string, string, boolean?][] | undefined,
     getState: any,
@@ -365,7 +382,7 @@ function handleServerside(
     let moreArgs = additionalArgs;
 
     if (running) {
-        sideUpdate(running.running, dispatch, paths);
+        sideUpdate(running.running, dispatch);
         runningOff = running.runningOff;
     }
 
@@ -475,10 +492,10 @@ function handleServerside(
                     dispatch(removeCallbackJob({jobId: job}));
                 }
                 if (runningOff) {
-                    sideUpdate(runningOff, dispatch, paths);
+                    sideUpdate(runningOff, dispatch);
                 }
                 if (progressDefault) {
-                    sideUpdate(progressDefault, dispatch, paths);
+                    sideUpdate(progressDefault, dispatch);
                 }
             };
 
@@ -500,8 +517,12 @@ function handleServerside(
                         job = data.job;
                     }
 
+                    if (data.sideUpdate) {
+                        sideUpdate(data.sideUpdate, dispatch);
+                    }
+
                     if (data.progress) {
-                        sideUpdate(data.progress, dispatch, paths);
+                        sideUpdate(data.progress, dispatch);
                     }
                     if (!progressDefault && data.progressDefault) {
                         progressDefault = data.progressDefault;
@@ -696,11 +717,7 @@ export function executeCallback(
                         if (inter.length) {
                             additionalArgs.push(['cancelJob', job.jobId]);
                             if (job.progressDefault) {
-                                sideUpdate(
-                                    job.progressDefault,
-                                    dispatch,
-                                    paths
-                                );
+                                sideUpdate(job.progressDefault, dispatch);
                             }
                         }
                     }
@@ -713,7 +730,6 @@ export function executeCallback(
                             hooks,
                             newConfig,
                             payload,
-                            paths,
                             long,
                             additionalArgs.length ? additionalArgs : undefined,
                             getState,
diff --git a/dash/dash-renderer/src/actions/dependencies.js b/dash/dash-renderer/src/actions/dependencies.js
index 34f7a90f59..223b3f8c4c 100644
--- a/dash/dash-renderer/src/actions/dependencies.js
+++ b/dash/dash-renderer/src/actions/dependencies.js
@@ -191,10 +191,6 @@ function validateDependencies(parsedDependencies, dispatchError) {
         let hasOutputs = true;
         if (outputs.length === 1 && !outputs[0].id && !outputs[0].property) {
             hasOutputs = false;
-            dispatchError('A callback is missing Outputs', [
-                'Please provide an output for this callback:',
-                JSON.stringify(dep, null, 2)
-            ]);
         }
 
         const head =
@@ -238,8 +234,22 @@ function validateDependencies(parsedDependencies, dispatchError) {
             });
         });
 
-        findDuplicateOutputs(outputs, head, dispatchError, outStrs, outObjs);
-        findMismatchedWildcards(outputs, inputs, state, head, dispatchError);
+        if (hasOutputs) {
+            findDuplicateOutputs(
+                outputs,
+                head,
+                dispatchError,
+                outStrs,
+                outObjs
+            );
+            findMismatchedWildcards(
+                outputs,
+                inputs,
+                state,
+                head,
+                dispatchError
+            );
+        }
     });
 }
 
@@ -382,7 +392,9 @@ function checkInOutOverlap(out, inputs) {
 }
 
 function findMismatchedWildcards(outputs, inputs, state, head, dispatchError) {
-    const {matchKeys: out0MatchKeys} = findWildcardKeys(outputs[0].id);
+    const {matchKeys: out0MatchKeys} = findWildcardKeys(
+        outputs.length ? outputs[0].id : undefined
+    );
     outputs.forEach((out, i) => {
         if (i && !equals(findWildcardKeys(out.id).matchKeys, out0MatchKeys)) {
             dispatchError('Mismatched `MATCH` wildcards across `Output`s', [
@@ -605,12 +617,21 @@ export function computeGraphs(dependencies, dispatchError) {
 
     const fixIds = map(evolve({id: parseIfWildcard}));
     const parsedDependencies = map(dep => {
-        const {output} = dep;
+        const {output, no_output} = dep;
         const out = evolve({inputs: fixIds, state: fixIds}, dep);
-        out.outputs = map(
-            outi => assoc('out', true, splitIdAndProp(outi)),
-            isMultiOutputProp(output) ? parseMultipleOutputs(output) : [output]
-        );
+        if (no_output) {
+            // No output case
+            out.outputs = [];
+            out.noOutput = true;
+        } else {
+            out.outputs = map(
+                outi => assoc('out', true, splitIdAndProp(outi)),
+                isMultiOutputProp(output)
+                    ? parseMultipleOutputs(output)
+                    : [output]
+            );
+        }
+
         return out;
     }, dependencies);
 
@@ -809,7 +830,9 @@ export function computeGraphs(dependencies, dispatchError) {
         // Also collect MATCH keys in the output (all outputs must share these)
         // and ALL keys in the first output (need not be shared but we'll use
         // the first output for calculations) for later convenience.
-        const {matchKeys} = findWildcardKeys(outputs[0].id);
+        const {matchKeys} = findWildcardKeys(
+            outputs.length ? outputs[0].id : undefined
+        );
         const firstSingleOutput = findIndex(o => !isMultiValued(o.id), outputs);
         const finalDependency = mergeRight(
             {matchKeys, firstSingleOutput, outputs},
@@ -1091,9 +1114,7 @@ export function addAllResolvedFromOutputs(resolve, paths, matches) {
             }
         } else {
             const cb = makeResolvedCallback(callback, resolve, '');
-            if (flatten(cb.getOutputs(paths)).length) {
-                matches.push(cb);
-            }
+            matches.push(cb);
         }
     };
 }
diff --git a/dash/dash-renderer/src/types/callbacks.ts b/dash/dash-renderer/src/types/callbacks.ts
index 62fcb19d20..fe8fd03ba7 100644
--- a/dash/dash-renderer/src/types/callbacks.ts
+++ b/dash/dash-renderer/src/types/callbacks.ts
@@ -103,4 +103,5 @@ export type CallbackResponseData = {
     running?: CallbackResponse;
     runningOff?: CallbackResponse;
     cancel?: ICallbackProperty[];
+    sideUpdate?: any;
 };
diff --git a/dash/dash.py b/dash/dash.py
index 1876eecd15..8b42d41bbb 100644
--- a/dash/dash.py
+++ b/dash/dash.py
@@ -1273,7 +1273,7 @@ def dispatch(self):
             "state", []
         )
         output = body["output"]
-        outputs_list = body.get("outputs") or split_callback_id(output)
+        outputs_list = body.get("outputs")
         g.outputs_list = outputs_list  # pylint: disable=assigning-non-slot
 
         g.input_values = (  # pylint: disable=assigning-non-slot
@@ -1305,6 +1305,12 @@ def dispatch(self):
             inputs_state = inputs + state
             inputs_state = convert_to_AttributeDict(inputs_state)
 
+            if cb.get("no_output"):
+                outputs_list = []
+            elif not outputs_list:
+                # FIXME Old renderer support?
+                split_callback_id(output)
+
             # update args_grouping attributes
             for s in inputs_state:
                 # check for pattern matching: list of inputs or state
@@ -1333,14 +1339,21 @@ def dispatch(self):
             else:
                 flat_outputs = outputs_list
 
-            outputs_grouping = map_grouping(
-                lambda ind: flat_outputs[ind], outputs_indices
-            )
-            g.outputs_grouping = outputs_grouping  # pylint: disable=assigning-non-slot
-            g.using_outputs_grouping = (  # pylint: disable=assigning-non-slot
-                not isinstance(outputs_indices, int)
-                and outputs_indices != list(range(grouping_len(outputs_indices)))
-            )
+            if len(flat_outputs) > 0:
+                outputs_grouping = map_grouping(
+                    lambda ind: flat_outputs[ind], outputs_indices
+                )
+                g.outputs_grouping = (
+                    outputs_grouping  # pylint: disable=assigning-non-slot
+                )
+                g.using_outputs_grouping = (  # pylint: disable=assigning-non-slot
+                    not isinstance(outputs_indices, int)
+                    and outputs_indices != list(range(grouping_len(outputs_indices)))
+                )
+            else:
+                g.outputs_grouping = []
+                g.using_outputs_grouping = []
+            g.updated_props = {}
 
         except KeyError as missing_callback_function:
             msg = f"Callback function not found for output '{output}', perhaps you forgot to prepend the '@'?"
diff --git a/dash/long_callback/_proxy_set_props.py b/dash/long_callback/_proxy_set_props.py
new file mode 100644
index 0000000000..3327305f3f
--- /dev/null
+++ b/dash/long_callback/_proxy_set_props.py
@@ -0,0 +1,7 @@
+class ProxySetProps(dict):
+    def __init__(self, on_change):
+        super().__init__()
+        self.on_change = on_change
+
+    def __setitem__(self, key, value):
+        self.on_change(key, value)
diff --git a/dash/long_callback/managers/__init__.py b/dash/long_callback/managers/__init__.py
index cf5dcd2182..bda99a1cde 100644
--- a/dash/long_callback/managers/__init__.py
+++ b/dash/long_callback/managers/__init__.py
@@ -51,6 +51,9 @@ def result_ready(self, key):
     def get_result(self, key, job):
         raise NotImplementedError
 
+    def get_updated_props(self, key):
+        raise NotImplementedError
+
     def build_cache_key(self, fn, args, cache_args_to_ignore):
         fn_source = inspect.getsource(fn)
 
@@ -98,6 +101,10 @@ def register_func(fn, progress, callback_id):
     def _make_progress_key(key):
         return key + "-progress"
 
+    @staticmethod
+    def _make_set_props_key(key):
+        return f"{key}-set_props"
+
     @staticmethod
     def hash_function(fn, callback_id=""):
         fn_source = inspect.getsource(fn)
diff --git a/dash/long_callback/managers/celery_manager.py b/dash/long_callback/managers/celery_manager.py
index 5090d42178..01fadf4f8d 100644
--- a/dash/long_callback/managers/celery_manager.py
+++ b/dash/long_callback/managers/celery_manager.py
@@ -7,6 +7,7 @@
 from dash._callback_context import context_value
 from dash._utils import AttributeDict
 from dash.exceptions import PreventUpdate
+from dash.long_callback._proxy_set_props import ProxySetProps
 from dash.long_callback.managers import BaseLongCallbackManager
 
 
@@ -124,6 +125,15 @@ def get_result(self, key, job):
         self.terminate_job(job)
         return result
 
+    def get_updated_props(self, key):
+        updated_props = self.handle.backend.get(self._make_set_props_key(key))
+        if updated_props is None:
+            return {}
+
+        self.clear_cache_entry(key)
+
+        return json.loads(updated_props)
+
 
 def _make_job_fn(fn, celery_app, progress, key):
     cache = celery_app.backend
@@ -138,11 +148,18 @@ def _set_progress(progress_value):
 
         maybe_progress = [_set_progress] if progress else []
 
+        def _set_props(_id, props):
+            cache.set(
+                f"{result_key}-set_props",
+                json.dumps({_id: props}, cls=PlotlyJSONEncoder),
+            )
+
         ctx = copy_context()
 
         def run():
             c = AttributeDict(**context)
             c.ignore_register_page = False
+            c.updated_props = ProxySetProps(_set_props)
             context_value.set(c)
             try:
                 if isinstance(user_callback_args, dict):
diff --git a/dash/long_callback/managers/diskcache_manager.py b/dash/long_callback/managers/diskcache_manager.py
index 22fb7bd5c5..a106700f82 100644
--- a/dash/long_callback/managers/diskcache_manager.py
+++ b/dash/long_callback/managers/diskcache_manager.py
@@ -2,6 +2,7 @@
 from contextvars import copy_context
 
 from . import BaseLongCallbackManager
+from .._proxy_set_props import ProxySetProps
 from ..._callback_context import context_value
 from ..._utils import AttributeDict
 from ...exceptions import PreventUpdate
@@ -155,6 +156,16 @@ def get_result(self, key, job):
             self.terminate_job(job)
         return result
 
+    def get_updated_props(self, key):
+        set_props_key = self._make_set_props_key(key)
+        result = self.handle.get(set_props_key, self.UNDEFINED)
+        if result is self.UNDEFINED:
+            return {}
+
+        self.clear_cache_entry(set_props_key)
+
+        return result
+
 
 def _make_job_fn(fn, cache, progress):
     def job_fn(result_key, progress_key, user_callback_args, context):
@@ -166,11 +177,15 @@ def _set_progress(progress_value):
 
         maybe_progress = [_set_progress] if progress else []
 
+        def _set_props(_id, props):
+            cache.set(f"{result_key}-set_props", {_id: props})
+
         ctx = copy_context()
 
         def run():
             c = AttributeDict(**context)
             c.ignore_register_page = False
+            c.updated_props = ProxySetProps(_set_props)
             context_value.set(c)
             try:
                 if isinstance(user_callback_args, dict):

From 6623750d6800b7193d24c9f98382f296bed47083 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 2 Apr 2024 13:03:18 -0400
Subject: [PATCH 02/21] Fix dvcv001

---
 tests/integration/devtools/test_callback_validation.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/tests/integration/devtools/test_callback_validation.py b/tests/integration/devtools/test_callback_validation.py
index 0e758a6889..59b874012e 100644
--- a/tests/integration/devtools/test_callback_validation.py
+++ b/tests/integration/devtools/test_callback_validation.py
@@ -70,10 +70,6 @@ def x():
         dash_duo,
         [
             ["A callback is missing Inputs", ["there are no `Input` elements."]],
-            [
-                "A callback is missing Outputs",
-                ["Please provide an output for this callback:"],
-            ],
         ],
     )
 

From 2f840220a8fd004853efdfbc3a7d94a12474a35f Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 2 Apr 2024 13:26:18 -0400
Subject: [PATCH 03/21] Fix test_grouped_callbacks.

---
 dash/_callback.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dash/_callback.py b/dash/_callback.py
index 7b6f305038..758c8ac0cc 100644
--- a/dash/_callback.py
+++ b/dash/_callback.py
@@ -337,7 +337,9 @@ def wrap_func(func):
         def add_context(*args, **kwargs):
             output_spec = kwargs.pop("outputs_list")
             app_callback_manager = kwargs.pop("long_callback_manager", None)
-            callback_ctx = kwargs.pop("callback_context", {})
+            callback_ctx = kwargs.pop(
+                "callback_context", AttributeDict({"updated_props": {}})
+            )
             callback_manager = long and long.get("manager", app_callback_manager)
             if not no_output:
                 _validate.validate_output_spec(insert_output, output_spec, Output)

From fb60ce0a6aa3ad4e9f2efd8b5f70600998649526 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 9 Apr 2024 11:14:24 -0400
Subject: [PATCH 04/21] Add test arbitrary callbacks.

---
 .../callbacks/test_arbitrary_callbacks.py     | 123 ++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 tests/integration/callbacks/test_arbitrary_callbacks.py

diff --git a/tests/integration/callbacks/test_arbitrary_callbacks.py b/tests/integration/callbacks/test_arbitrary_callbacks.py
new file mode 100644
index 0000000000..f5c4612eaa
--- /dev/null
+++ b/tests/integration/callbacks/test_arbitrary_callbacks.py
@@ -0,0 +1,123 @@
+from dash import Dash, Input, Output, html, set_props, register_page
+
+
+def test_arb001_global_set_props(dash_duo):
+    app = Dash()
+    app.layout = html.Div(
+        [
+            html.Div(id="output"),
+            html.Div(id="secondary-output"),
+            html.Button("click", id="clicker"),
+        ]
+    )
+
+    @app.callback(
+        Output("output", "children"),
+        Input("clicker", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def on_click(n_clicks):
+        set_props("secondary-output", {"children": "secondary"})
+        return f"Clicked {n_clicks} times"
+
+    dash_duo.start_server(app)
+
+    dash_duo.wait_for_element("#clicker").click()
+    dash_duo.wait_for_text_to_equal("#output", "Clicked 1 times")
+    dash_duo.wait_for_text_to_equal("#secondary-output", "secondary")
+
+
+def test_arb002_no_output_callbacks(dash_duo):
+    app = Dash()
+
+    app.layout = html.Div(
+        [
+            html.Div(id="secondary-output"),
+            html.Button("no-output", id="no-output"),
+            html.Button("no-output2", id="no-output2"),
+        ]
+    )
+
+    @app.callback(
+        Input("no-output", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def no_output(_):
+        set_props("secondary-output", {"children": "no-output"})
+
+    @app.callback(
+        Input("no-output2", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def no_output(_):
+        set_props("secondary-output", {"children": "no-output2"})
+
+    dash_duo.start_server(app)
+
+    dash_duo.wait_for_element("#no-output").click()
+    dash_duo.wait_for_text_to_equal("#secondary-output", "no-output")
+
+    dash_duo.wait_for_element("#no-output2").click()
+    dash_duo.wait_for_text_to_equal("#secondary-output", "no-output2")
+
+
+def test_arb003_arbitrary_pages(dash_duo):
+    app = Dash(use_pages=True, pages_folder="")
+
+    register_page(
+        "page",
+        "/",
+        layout=html.Div(
+            [
+                html.Div(id="secondary-output"),
+                html.Button("no-output", id="no-output"),
+                html.Button("no-output2", id="no-output2"),
+            ]
+        ),
+    )
+
+    @app.callback(
+        Input("no-output", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def no_output(_):
+        set_props("secondary-output", {"children": "no-output"})
+
+    @app.callback(
+        Input("no-output2", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def no_output(_):
+        set_props("secondary-output", {"children": "no-output2"})
+
+    dash_duo.start_server(app)
+
+    dash_duo.wait_for_element("#no-output").click()
+    dash_duo.wait_for_text_to_equal("#secondary-output", "no-output")
+
+    dash_duo.wait_for_element("#no-output2").click()
+    dash_duo.wait_for_text_to_equal("#secondary-output", "no-output2")
+
+
+def test_arb004_wildcard_set_props(dash_duo):
+    app = Dash()
+    app.layout = html.Div(
+        [
+            html.Button("click", id="click"),
+            html.Div(html.Div(id={"id": "output", "index": 0}), id="output"),
+        ]
+    )
+
+    @app.callback(
+        Input("click", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def on_click(n_clicks):
+        set_props(
+            {"id": "output", "index": 0}, {"children": f"Clicked {n_clicks} times"}
+        )
+
+    dash_duo.start_server(app)
+
+    dash_duo.wait_for_element("#click").click()
+    dash_duo.wait_for_text_to_equal("#output", "Clicked 1 times")

From a9f757cab68026017b04460092c803ccd533e626 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 10 Apr 2024 11:08:32 -0400
Subject: [PATCH 05/21] Add test arbitrary callbacks for background callbacks.

---
 dash/_callback.py                             |  3 +-
 .../long_callback/app_arbitrary.py            | 48 +++++++++++++++++++
 .../test_basic_long_callback017.py            | 19 ++++++++
 3 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 tests/integration/long_callback/app_arbitrary.py
 create mode 100644 tests/integration/long_callback/test_basic_long_callback017.py

diff --git a/dash/_callback.py b/dash/_callback.py
index 758c8ac0cc..d0d39ef3d8 100644
--- a/dash/_callback.py
+++ b/dash/_callback.py
@@ -351,6 +351,7 @@ def add_context(*args, **kwargs):
             )
 
             response = {"multi": True}
+            has_update = False
 
             if long is not None:
                 if not callback_manager:
@@ -455,6 +456,7 @@ def add_context(*args, **kwargs):
                 updated_props = callback_manager.get_updated_props(cache_key)
                 if len(updated_props) > 0:
                     response["sideUpdate"] = updated_props
+                    has_update = True
 
                 if output_value is callback_manager.UNDEFINED:
                     return to_json(response)
@@ -480,7 +482,6 @@ def add_context(*args, **kwargs):
                 flat_output_values = flatten_grouping(output_value, output)
 
             component_ids = collections.defaultdict(dict)
-            has_update = False
             if not no_output:
                 _validate.validate_multi_return(
                     output_spec, flat_output_values, callback_id
diff --git a/tests/integration/long_callback/app_arbitrary.py b/tests/integration/long_callback/app_arbitrary.py
new file mode 100644
index 0000000000..e09f08de34
--- /dev/null
+++ b/tests/integration/long_callback/app_arbitrary.py
@@ -0,0 +1,48 @@
+from dash import Dash, Input, Output, html, callback, set_props
+import time
+
+from tests.integration.long_callback.utils import get_long_callback_manager
+
+long_callback_manager = get_long_callback_manager()
+handle = long_callback_manager.handle
+
+app = Dash(__name__, long_callback_manager=long_callback_manager)
+app.test_lock = lock = long_callback_manager.test_lock
+
+app.layout = html.Div(
+    [
+        html.Button("start", id="start"),
+        html.Div(id="secondary"),
+        html.Div(id="no-output"),
+        html.Div("initial", id="output"),
+        html.Button("start-no-output", id="start-no-output"),
+    ]
+)
+
+
+@callback(
+    Output("output", "children"),
+    Input("start", "n_clicks"),
+    prevent_initial_call=True,
+    background=True,
+)
+def on_click(_):
+    set_props("secondary", {"children": "first"})
+    time.sleep(2)
+    set_props("secondary", {"children": "second"})
+    return "completed"
+
+
+@callback(
+    Input("start-no-output", "n_clicks"),
+    prevent_initial_call=True,
+    background=True,
+)
+def on_click(_):
+    set_props("no-output", {"children": "started"})
+    time.sleep(2)
+    set_props("no-output", {"children": "completed"})
+
+
+if __name__ == "__main__":
+    app.run_server(debug=True)
diff --git a/tests/integration/long_callback/test_basic_long_callback017.py b/tests/integration/long_callback/test_basic_long_callback017.py
new file mode 100644
index 0000000000..599d22f132
--- /dev/null
+++ b/tests/integration/long_callback/test_basic_long_callback017.py
@@ -0,0 +1,19 @@
+from tests.integration.long_callback.utils import setup_long_callback_app
+
+
+def test_lcbc017_long_callback_set_props(dash_duo, manager):
+    with setup_long_callback_app(manager, "app_arbitrary") as app:
+        dash_duo.start_server(app)
+
+        with app.test_lock:
+            dash_duo.find_element("#start").click()
+
+        dash_duo.wait_for_text_to_equal("#secondary", "first")
+        dash_duo.wait_for_text_to_equal("#output", "initial")
+        dash_duo.wait_for_text_to_equal("#secondary", "second")
+        dash_duo.wait_for_text_to_equal("#output", "completed")
+
+        dash_duo.find_element("#start-no-output").click()
+
+        dash_duo.wait_for_text_to_equal("#no-output", "started")
+        dash_duo.wait_for_text_to_equal("#no-output", "completed")

From d6564d85f44f179e0fe8a9c79d85e22a681c3f4f Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 10 Apr 2024 11:41:41 -0400
Subject: [PATCH 06/21] Remove lock from test.

---
 tests/integration/long_callback/test_basic_long_callback017.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tests/integration/long_callback/test_basic_long_callback017.py b/tests/integration/long_callback/test_basic_long_callback017.py
index 599d22f132..bef39d3eed 100644
--- a/tests/integration/long_callback/test_basic_long_callback017.py
+++ b/tests/integration/long_callback/test_basic_long_callback017.py
@@ -5,8 +5,7 @@ def test_lcbc017_long_callback_set_props(dash_duo, manager):
     with setup_long_callback_app(manager, "app_arbitrary") as app:
         dash_duo.start_server(app)
 
-        with app.test_lock:
-            dash_duo.find_element("#start").click()
+        dash_duo.find_element("#start").click()
 
         dash_duo.wait_for_text_to_equal("#secondary", "first")
         dash_duo.wait_for_text_to_equal("#output", "initial")

From 00baa48e4c09196d11730e720a810f2a0290c08f Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 23 Apr 2024 09:03:50 -0400
Subject: [PATCH 07/21] reuse hashing

---
 dash/_utils.py | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/dash/_utils.py b/dash/_utils.py
index bb388d65b6..c2577a8a09 100644
--- a/dash/_utils.py
+++ b/dash/_utils.py
@@ -137,23 +137,24 @@ def create_callback_id(output, inputs, no_output=False):
     # with `\` so we don't mistake it for multi-outputs
     hashed_inputs = None
 
+    def _hash_inputs():
+        return hashlib.sha256(
+            ".".join(str(x) for x in inputs).encode("utf-8")
+        ).hexdigest()
+
     def _concat(x):
         nonlocal hashed_inputs
         _id = x.component_id_str().replace(".", "\\.") + "." + x.component_property
         if x.allow_duplicate:
             if not hashed_inputs:
-                hashed_inputs = hashlib.sha256(
-                    ".".join(str(x) for x in inputs).encode("utf-8")
-                ).hexdigest()
+                hashed_inputs = _hash_inputs
             # Actually adds on the property part.
             _id += f"@{hashed_inputs}"
         return _id
 
     if no_output:
         # No output will hash the inputs.
-        return hashlib.sha256(
-            ".".join(str(x) for x in inputs).encode("utf-8")
-        ).hexdigest()
+        return _hash_inputs
 
     if isinstance(output, (list, tuple)):
         return ".." + "...".join(_concat(x) for x in output) + ".."

From d57134b1bd10415dda482d0a98be66a7814b3fb9 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 23 Apr 2024 09:37:21 -0400
Subject: [PATCH 08/21] reuse hashing

---
 dash/_utils.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dash/_utils.py b/dash/_utils.py
index c2577a8a09..4d67cb39dd 100644
--- a/dash/_utils.py
+++ b/dash/_utils.py
@@ -147,14 +147,14 @@ def _concat(x):
         _id = x.component_id_str().replace(".", "\\.") + "." + x.component_property
         if x.allow_duplicate:
             if not hashed_inputs:
-                hashed_inputs = _hash_inputs
+                hashed_inputs = _hash_inputs()
             # Actually adds on the property part.
             _id += f"@{hashed_inputs}"
         return _id
 
     if no_output:
         # No output will hash the inputs.
-        return _hash_inputs
+        return _hash_inputs()
 
     if isinstance(output, (list, tuple)):
         return ".." + "...".join(_concat(x) for x in output) + ".."

From f1a92a399710c80450d5c11a0f0a657d20de6b1c Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 23 Apr 2024 10:23:57 -0400
Subject: [PATCH 09/21] Improve sideUpdate

---
 dash/dash-renderer/src/actions/callbacks.ts | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/dash/dash-renderer/src/actions/callbacks.ts b/dash/dash-renderer/src/actions/callbacks.ts
index 845fcc7eee..bb55997c84 100644
--- a/dash/dash-renderer/src/actions/callbacks.ts
+++ b/dash/dash-renderer/src/actions/callbacks.ts
@@ -343,18 +343,16 @@ function sideUpdate(outputs: any, dispatch: any) {
         let componentId, propName;
         if (id.includes('.')) {
             [componentId, propName] = id.split('.');
-            if (componentId.startsWith('{')) {
-                componentId = JSON.parse(componentId);
-            }
-            dispatch(updateComponent(componentId, {[propName]: value}));
         } else {
-            if (id.startsWith('{')) {
-                componentId = JSON.parse(id);
-            } else {
-                componentId = id;
-            }
-            dispatch(updateComponent(componentId, value));
+            componentId = id;
+        }
+
+        if (componentId.startsWith('{')) {
+            componentId = JSON.parse(componentId);
         }
+
+        const props = propName ? {[propName]: value} : value;
+        dispatch(updateComponent(componentId, props));
     });
 }
 

From b1a0529ca47c3c71a94fde07aa9bb6f57a7f1a26 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 23 Apr 2024 11:35:20 -0400
Subject: [PATCH 10/21] Add error when returning value in no output callbacks.

---
 dash/_callback.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/dash/_callback.py b/dash/_callback.py
index 9424c031ac..35e57528ab 100644
--- a/dash/_callback.py
+++ b/dash/_callback.py
@@ -10,6 +10,7 @@
     Output,
 )
 from .exceptions import (
+    InvalidCallbackReturnValue,
     PreventUpdate,
     WildcardInLongCallback,
     MissingLongCallbackManagerError,
@@ -467,6 +468,10 @@ def add_context(*args, **kwargs):
                 raise PreventUpdate
 
             if no_output:
+                if output_value is not None:
+                    raise InvalidCallbackReturnValue(
+                        f"No output callback received return value: {output_value}"
+                    )
                 output_value = []
                 flat_output_values = []
             elif not multi:

From dfdb6056496443462435d9aa0590c42135cd0d69 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Tue, 23 Apr 2024 14:40:26 -0400
Subject: [PATCH 11/21] Add ProxySetProps docstring

---
 dash/long_callback/_proxy_set_props.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/dash/long_callback/_proxy_set_props.py b/dash/long_callback/_proxy_set_props.py
index 3327305f3f..52f0af70a6 100644
--- a/dash/long_callback/_proxy_set_props.py
+++ b/dash/long_callback/_proxy_set_props.py
@@ -1,4 +1,9 @@
 class ProxySetProps(dict):
+    """
+    Defer dictionary item setter to run a custom function on change.
+    Used by background callback manager to save the `set_props` data.
+    """
+
     def __init__(self, on_change):
         super().__init__()
         self.on_change = on_change

From 8891a71546b1e5689869b6bc7eb4e8d3f54200f5 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 24 Apr 2024 11:18:33 -0400
Subject: [PATCH 12/21] use stringigfy_id

---
 dash/_callback_context.py |  8 +++-----
 dash/dependencies.py      | 16 ++--------------
 2 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/dash/_callback_context.py b/dash/_callback_context.py
index db82d5aaee..aaa721369e 100644
--- a/dash/_callback_context.py
+++ b/dash/_callback_context.py
@@ -7,7 +7,7 @@
 import flask
 
 from . import exceptions
-from ._utils import AttributeDict
+from ._utils import AttributeDict, stringify_id
 
 
 context_value = contextvars.ContextVar("callback_context")
@@ -251,10 +251,8 @@ def timing_information(self):
     @has_context
     def set_props(self, component_id: typing.Union[str, dict], props: dict):
         ctx_value = _get_context_value()
-        if isinstance(component_id, dict):
-            ctx_value.updated_props[json.dumps(component_id)] = props
-        else:
-            ctx_value.updated_props[component_id] = props
+        _id = stringify_id(component_id)
+        ctx_value.updated_props[_id] = props
 
 
 callback_context = CallbackContext()
diff --git a/dash/dependencies.py b/dash/dependencies.py
index 2e2ce322c7..819d134546 100644
--- a/dash/dependencies.py
+++ b/dash/dependencies.py
@@ -1,8 +1,8 @@
-import json
 from dash.development.base_component import Component
 
 from ._validate import validate_callback
 from ._grouping import flatten_grouping, make_grouping_by_index
+from ._utils import stringify_id
 
 
 class _Wildcard:  # pylint: disable=too-few-public-methods
@@ -44,19 +44,7 @@ def __repr__(self):
         return f"<{self.__class__.__name__} `{self}`>"
 
     def component_id_str(self):
-        i = self.component_id
-
-        def _dump(v):
-            return json.dumps(v, sort_keys=True, separators=(",", ":"))
-
-        def _json(k, v):
-            vstr = v.to_json() if hasattr(v, "to_json") else json.dumps(v)
-            return f"{json.dumps(k)}:{vstr}"
-
-        if isinstance(i, dict):
-            return "{" + ",".join(_json(k, i[k]) for k in sorted(i)) + "}"
-
-        return i
+        return stringify_id(self.component_id)
 
     def to_dict(self):
         return {"id": self.component_id_str(), "property": self.component_property}

From 939c0100adcb62e6624e39bf465c9f421a28c580 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 24 Apr 2024 11:25:51 -0400
Subject: [PATCH 13/21] rollback pylintrc change

---
 .pylintrc    | 2 +-
 dash/dash.py | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/.pylintrc b/.pylintrc
index db7fac560e..554f953b8e 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -426,7 +426,7 @@ max-public-methods=40
 max-returns=6
 
 # Maximum number of statements in function / method body
-max-statements=75
+max-statements=50
 
 # Minimum number of public methods for a class (see R0903).
 min-public-methods=2
diff --git a/dash/dash.py b/dash/dash.py
index 4ca11c0fed..b17ef80c96 100644
--- a/dash/dash.py
+++ b/dash/dash.py
@@ -1266,6 +1266,7 @@ def long_callback(
             **_kwargs,
         )
 
+    # pylint: disable=R0915
     def dispatch(self):
         body = flask.request.get_json()
 

From b12c4817653d4399fd083709352768e6ecdf1b36 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 24 Apr 2024 11:55:54 -0400
Subject: [PATCH 14/21] fix stringify_id

---
 dash/_utils.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/dash/_utils.py b/dash/_utils.py
index 4d67cb39dd..38ff0c39ac 100644
--- a/dash/_utils.py
+++ b/dash/_utils.py
@@ -174,8 +174,12 @@ def split_callback_id(callback_id):
 
 
 def stringify_id(id_):
+    def _json(k, v):
+        vstr = v.to_json() if hasattr(v, "to_json") else json.dumps(v)
+        return f"{json.dumps(k)}:{vstr}"
+
     if isinstance(id_, dict):
-        return json.dumps(id_, sort_keys=True, separators=(",", ":"))
+        return "{" + ",".join(_json(k, id_[k]) for k in sorted(id_)) + "}"
     return id_
 
 

From dfaf5d1005bebc6bbdc6b6c4a123e6789e3e9758 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 24 Apr 2024 16:36:36 -0400
Subject: [PATCH 15/21] Fix case where the dict id contains a dot

---
 dash/dash-renderer/src/actions/callbacks.ts | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/dash/dash-renderer/src/actions/callbacks.ts b/dash/dash-renderer/src/actions/callbacks.ts
index bb55997c84..20961199ff 100644
--- a/dash/dash-renderer/src/actions/callbacks.ts
+++ b/dash/dash-renderer/src/actions/callbacks.ts
@@ -340,15 +340,19 @@ function updateComponent(component_id: any, props: any) {
 
 function sideUpdate(outputs: any, dispatch: any) {
     toPairs(outputs).forEach(([id, value]) => {
-        let componentId, propName;
-        if (id.includes('.')) {
+        let componentId = id,
+            propName;
+
+        if (id.startsWith('{')) {
+            const index = id.lastIndexOf('}');
+            if (index + 2 < id.length) {
+                propName = id.substring(index + 2);
+                componentId = JSON.parse(id.substring(0, index + 1));
+            } else {
+                componentId = JSON.parse(id);
+            }
+        } else if (id.includes('.')) {
             [componentId, propName] = id.split('.');
-        } else {
-            componentId = id;
-        }
-
-        if (componentId.startsWith('{')) {
-            componentId = JSON.parse(componentId);
         }
 
         const props = propName ? {[propName]: value} : value;

From 63604214ff1d50116d161591a429988b1fad784d Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Thu, 25 Apr 2024 14:21:10 -0400
Subject: [PATCH 16/21] Refactor no_output variable to has_output and less
 branching

---
 dash/_callback.py | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/dash/_callback.py b/dash/_callback.py
index 35e57528ab..35a3168096 100644
--- a/dash/_callback.py
+++ b/dash/_callback.py
@@ -287,12 +287,12 @@ def register_callback(  # pylint: disable=R0914
         # Insert callback with scalar (non-multi) Output
         insert_output = output
         multi = False
-        no_output = False
+        has_output = True
     else:
         # Insert callback as multi Output
         insert_output = flatten_grouping(output)
         multi = True
-        no_output = len(output) == 0
+        has_output = len(output) > 0
 
     long = _kwargs.get("long")
     manager = _kwargs.get("manager")
@@ -321,7 +321,7 @@ def register_callback(  # pylint: disable=R0914
         manager=manager,
         dynamic_creator=allow_dynamic_callbacks,
         running=running,
-        no_output=no_output,
+        no_output=not has_output,
     )
 
     # pylint: disable=too-many-locals
@@ -342,7 +342,7 @@ def add_context(*args, **kwargs):
                 "callback_context", AttributeDict({"updated_props": {}})
             )
             callback_manager = long and long.get("manager", app_callback_manager)
-            if not no_output:
+            if has_output:
                 _validate.validate_output_spec(insert_output, output_spec, Output)
 
             context_value.set(callback_ctx)
@@ -467,27 +467,28 @@ def add_context(*args, **kwargs):
             if NoUpdate.is_no_update(output_value):
                 raise PreventUpdate
 
-            if no_output:
+            component_ids = collections.defaultdict(dict)
+
+            if not has_output:
                 if output_value is not None:
                     raise InvalidCallbackReturnValue(
                         f"No output callback received return value: {output_value}"
                     )
                 output_value = []
                 flat_output_values = []
-            elif not multi:
-                output_value, output_spec = [output_value], [output_spec]
-                flat_output_values = output_value
             else:
-                if isinstance(output_value, (list, tuple)):
-                    # For multi-output, allow top-level collection to be
-                    # list or tuple
-                    output_value = list(output_value)
+                if not multi:
+                    output_value, output_spec = [output_value], [output_spec]
+                    flat_output_values = output_value
+                else:
+                    if isinstance(output_value, (list, tuple)):
+                        # For multi-output, allow top-level collection to be
+                        # list or tuple
+                        output_value = list(output_value)
+
+                    # Flatten grouping and validate grouping structure
+                    flat_output_values = flatten_grouping(output_value, output)
 
-                # Flatten grouping and validate grouping structure
-                flat_output_values = flatten_grouping(output_value, output)
-
-            component_ids = collections.defaultdict(dict)
-            if not no_output:
                 _validate.validate_multi_return(
                     output_spec, flat_output_values, callback_id
                 )

From 2b29699492730278842b3ec24ff4c96d3e8ce9d0 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Thu, 25 Apr 2024 14:53:06 -0400
Subject: [PATCH 17/21] Update changelog

---
 CHANGELOG.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c2c04f9e3b..531ba7da8f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,11 +16,14 @@ This project adheres to [Semantic Versioning](https://semver.org/).
   - `target_components` specifies components/props triggering the loading spinner
   - `custom_spinner`  enables using a custom component for loading messages instead of built-in spinners
   - `display`  overrides the loading status with options for "show," "hide," or "auto"
+- [#2822](https://github.com/plotly/dash/pull/2822) Support no output callbacks. Fixes [#1549](https://github.com/plotly/dash/issues/1549)
+- [#2822](https://github.com/plotly/dash/pull/2822) Add global set_props. Fixes [#2803](https://github.com/plotly/dash/issues/2803)
 
 ## Fixed
 
 - [#2362](https://github.com/plotly/dash/pull/2362) Global namespace not polluted any more when loading clientside callbacks.
 - [#2833](https://github.com/plotly/dash/pull/2833) Allow data url in link props. Fixes [#2764](https://github.com/plotly/dash/issues/2764) 
+- [#2822](https://github.com/plotly/dash/pull/2822) Fix side update (running/progress/cancel) dict ids. Fixes [#2111](https://github.com/plotly/dash/issues/2111)
 
 ## [2.16.1] - 2024-03-06
 

From a1e461f829cf99e9f571177663edd19a90ecc56d Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Thu, 25 Apr 2024 14:54:56 -0400
Subject: [PATCH 18/21] Add no output counter test

---
 .../callbacks/test_arbitrary_callbacks.py     | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/tests/integration/callbacks/test_arbitrary_callbacks.py b/tests/integration/callbacks/test_arbitrary_callbacks.py
index f5c4612eaa..18269ecae9 100644
--- a/tests/integration/callbacks/test_arbitrary_callbacks.py
+++ b/tests/integration/callbacks/test_arbitrary_callbacks.py
@@ -1,3 +1,6 @@
+import time
+from multiprocessing import Value
+
 from dash import Dash, Input, Output, html, set_props, register_page
 
 
@@ -30,11 +33,14 @@ def on_click(n_clicks):
 def test_arb002_no_output_callbacks(dash_duo):
     app = Dash()
 
+    counter = Value("i", 0)
+
     app.layout = html.Div(
         [
             html.Div(id="secondary-output"),
             html.Button("no-output", id="no-output"),
             html.Button("no-output2", id="no-output2"),
+            html.Button("no-output3", id="no-output3"),
         ]
     )
 
@@ -42,16 +48,24 @@ def test_arb002_no_output_callbacks(dash_duo):
         Input("no-output", "n_clicks"),
         prevent_initial_call=True,
     )
-    def no_output(_):
+    def no_output1(_):
         set_props("secondary-output", {"children": "no-output"})
 
     @app.callback(
         Input("no-output2", "n_clicks"),
         prevent_initial_call=True,
     )
-    def no_output(_):
+    def no_output2(_):
         set_props("secondary-output", {"children": "no-output2"})
 
+    @app.callback(
+        Input("no-output3", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def no_output3(_):
+        with counter.get_lock():
+            counter.value += 1
+
     dash_duo.start_server(app)
 
     dash_duo.wait_for_element("#no-output").click()
@@ -60,6 +74,12 @@ def no_output(_):
     dash_duo.wait_for_element("#no-output2").click()
     dash_duo.wait_for_text_to_equal("#secondary-output", "no-output2")
 
+    dash_duo.wait_for_element("#no-output3").click()
+
+    time.sleep(1)
+    with counter.get_lock():
+        assert counter.value == 1
+
 
 def test_arb003_arbitrary_pages(dash_duo):
     app = Dash(use_pages=True, pages_folder="")

From ad73c298bda0b39c964440d7c679b7102a5698cc Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Thu, 25 Apr 2024 15:21:32 -0400
Subject: [PATCH 19/21] reverse condition

---
 dash/_callback.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/dash/_callback.py b/dash/_callback.py
index 35a3168096..b5d471aa5d 100644
--- a/dash/_callback.py
+++ b/dash/_callback.py
@@ -469,14 +469,7 @@ def add_context(*args, **kwargs):
 
             component_ids = collections.defaultdict(dict)
 
-            if not has_output:
-                if output_value is not None:
-                    raise InvalidCallbackReturnValue(
-                        f"No output callback received return value: {output_value}"
-                    )
-                output_value = []
-                flat_output_values = []
-            else:
+            if has_output:
                 if not multi:
                     output_value, output_spec = [output_value], [output_spec]
                     flat_output_values = output_value
@@ -504,6 +497,13 @@ def add_context(*args, **kwargs):
                             id_str = stringify_id(speci["id"])
                             prop = clean_property_name(speci["property"])
                             component_ids[id_str][prop] = vali
+            else:
+                if output_value is not None:
+                    raise InvalidCallbackReturnValue(
+                        f"No output callback received return value: {output_value}"
+                    )
+                output_value = []
+                flat_output_values = []
 
             if not long:
                 side_update = dict(callback_ctx.updated_props)

From 33f6d742d3be80a3b3e41d37cf6c53c93af74a63 Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 1 May 2024 15:40:03 -0400
Subject: [PATCH 20/21] Better error message on no output callbacks exceptions

---
 .../src/observers/executedCallbacks.ts        | 19 ++++++++++-----
 dash/dash-renderer/src/types/callbacks.ts     |  1 +
 .../callbacks/test_arbitrary_callbacks.py     | 24 +++++++++++++++++++
 3 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/dash/dash-renderer/src/observers/executedCallbacks.ts b/dash/dash-renderer/src/observers/executedCallbacks.ts
index 76d78a3c06..1249252704 100644
--- a/dash/dash-renderer/src/observers/executedCallbacks.ts
+++ b/dash/dash-renderer/src/observers/executedCallbacks.ts
@@ -302,12 +302,19 @@ const observer: IStoreObserverDefinition<IStoreState> = {
             }
 
             if (error !== undefined) {
-                const outputs = payload
-                    ? map(combineIdAndProp, flatten([payload.outputs])).join(
-                          ', '
-                      )
-                    : output;
-                let message = `Callback error updating ${outputs}`;
+                let message;
+                if (cb.callback.no_output) {
+                    const inpts = keys(cb.changedPropIds).join(', ');
+                    message = `Callback error with no output from input ${inpts}`;
+                } else {
+                    const outputs = payload
+                        ? map(
+                              combineIdAndProp,
+                              flatten([payload.outputs])
+                          ).join(', ')
+                        : output;
+                    message = `Callback error updating ${outputs}`;
+                }
                 if (clientside_function) {
                     const {namespace: ns, function_name: fn} =
                         clientside_function;
diff --git a/dash/dash-renderer/src/types/callbacks.ts b/dash/dash-renderer/src/types/callbacks.ts
index fe8fd03ba7..33942b0281 100644
--- a/dash/dash-renderer/src/types/callbacks.ts
+++ b/dash/dash-renderer/src/types/callbacks.ts
@@ -14,6 +14,7 @@ export interface ICallbackDefinition {
     long?: LongCallbackInfo;
     dynamic_creator?: boolean;
     running: any;
+    no_output?: boolean;
 }
 
 export interface ICallbackProperty {
diff --git a/tests/integration/callbacks/test_arbitrary_callbacks.py b/tests/integration/callbacks/test_arbitrary_callbacks.py
index 18269ecae9..4441c44add 100644
--- a/tests/integration/callbacks/test_arbitrary_callbacks.py
+++ b/tests/integration/callbacks/test_arbitrary_callbacks.py
@@ -141,3 +141,27 @@ def on_click(n_clicks):
 
     dash_duo.wait_for_element("#click").click()
     dash_duo.wait_for_text_to_equal("#output", "Clicked 1 times")
+
+
+def test_arb005_no_output_error(dash_duo):
+    app = Dash()
+
+    app.layout = html.Div([html.Button("start", id="start")])
+
+    @app.callback(Input("start", "n_clicks"), prevent_initial_call=True)
+    def on_click(clicked):
+        return f"clicked {clicked}"
+
+    dash_duo.start_server(
+        app,
+        debug=True,
+        use_reloader=False,
+        use_debugger=True,
+        dev_tools_hot_reload=False,
+    )
+
+    dash_duo.wait_for_element("#start").click()
+    dash_duo.wait_for_text_to_equal(
+        ".dash-fe-error__title",
+        "Callback error with no output from input start.n_clicks",
+    )

From d367a6e115f67f7b4cbc401b2749155efbdd1f7d Mon Sep 17 00:00:00 2001
From: philippe <t4rk@outlook.com>
Date: Wed, 1 May 2024 16:01:51 -0400
Subject: [PATCH 21/21] No output -> No-output

---
 dash/_callback.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dash/_callback.py b/dash/_callback.py
index b5d471aa5d..3d63d4b21e 100644
--- a/dash/_callback.py
+++ b/dash/_callback.py
@@ -500,7 +500,7 @@ def add_context(*args, **kwargs):
             else:
                 if output_value is not None:
                     raise InvalidCallbackReturnValue(
-                        f"No output callback received return value: {output_value}"
+                        f"No-output callback received return value: {output_value}"
                     )
                 output_value = []
                 flat_output_values = []