Add filter by (#6090)

examples/reference/chat/ChatFeed.ipynb

@@ -604,6 +604,30 @@
     ")"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The messages can be filtered by using a custom `filter_by` function."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def filter_by_reactions(messages):\n",
+    "    return [message for message in messages if \"favorite\" in message.reactions]\n",
+    "\n",
+    "\n",
+    "chat_feed.send(\n",
+    "    pn.chat.ChatMessage(\"I'm a message with a reaction!\", reactions=[\"favorite\"])\n",
+    ")\n",
+    "\n",
+    "chat_feed.serialize(filter_by=filter_by_reactions)"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},

panel/chat/feed.py

@@ -694,6 +694,7 @@ def clear(self) -> List[Any]:
 
     def _serialize_for_transformers(
         self,
+        messages: List[ChatMessage],
         role_names: Dict[str, str | List[str]] | None = None,
         default_role: str | None = "assistant",
         custom_serializer: Callable = None
@@ -716,8 +717,8 @@ def _serialize_for_transformers(
             for name in names:
                 names_role[name.lower()] = role
 
-        messages = []
-        for message in self._chat_log.objects:
+        serialized_messages = []
+        for message in messages:
 
             lowercase_name = message.user.lower()
             if lowercase_name not in names_role and not default_role:
@@ -738,11 +739,12 @@ def _serialize_for_transformers(
             else:
                 content = str(message)
 
-            messages.append({"role": role, "content": content})
-        return messages
+            serialized_messages.append({"role": role, "content": content})
+        return serialized_messages
 
     def serialize(
         self,
+        filter_by: Callable | None = None,
         format: Literal["transformers"] = "transformers",
         custom_serializer: Callable | None = None,
         **serialize_kwargs
@@ -755,10 +757,13 @@ def serialize(
         format : str
             The format to export the chat log as; currently only
             supports "transformers".
+        filter_by : callable
+            A function to filter the chat log by.
+            The function must accept and return a list of ChatMessage objects.
         custom_serializer : callable
             A custom function to format the ChatMessage's object. The function must
-            accept one positional argument. If not provided,
-            uses the serialize method on ChatMessage.
+            accept one positional argument, the ChatMessage object, and return a string.
+            If not provided, uses the serialize method on ChatMessage.
         **serialize_kwargs
             Additional keyword arguments to use for the specified format.
 
@@ -777,9 +782,13 @@ def serialize(
         -------
         The chat log serialized in the specified format.
         """
+        messages = self._chat_log.objects.copy()
+        if filter_by is not None:
+            messages = filter_by(messages)
+
         if format == "transformers":
             return self._serialize_for_transformers(
-                custom_serializer=custom_serializer, **serialize_kwargs
+                messages, custom_serializer=custom_serializer, **serialize_kwargs
             )
         raise NotImplementedError(f"Format {format!r} is not supported.")
 

panel/chat/interface.py

@@ -23,7 +23,7 @@
 from ..widgets.button import Button
 from ..widgets.input import FileInput, TextInput
 from .feed import CallbackState, ChatFeed
-from .message import _FileInputMessage
+from .message import ChatMessage, _FileInputMessage
 
 
 @dataclass
@@ -543,6 +543,7 @@ def active(self, index: int) -> None:
 
     def _serialize_for_transformers(
         self,
+        messages: List[ChatMessage],
         role_names: Dict[str, str | List[str]] | None = None,
         default_role: str | None = "assistant",
         custom_serializer: Callable = None
@@ -552,6 +553,8 @@ def _serialize_for_transformers(
 
         Arguments
         ---------
+        messages : list(ChatMessage)
+            A list of ChatMessage objects to serialize.
         role_names : dict(str, str | list(str)) | None
             A dictionary mapping the role to the ChatMessage's user name.
             Defaults to `{"user": [self.user], "assistant": [self.callback_user]}`
@@ -563,8 +566,8 @@ def _serialize_for_transformers(
             If this is set to None, raises a ValueError if the user name is not found.
         custom_serializer : callable
             A custom function to format the ChatMessage's object. The function must
-            accept one positional argument and return a string. If not provided,
-            uses the serialize method on ChatMessage.
+            accept one positional argument, the ChatMessage object, and return a string.
+            If not provided, uses the serialize method on ChatMessage.
 
         Returns
         -------
@@ -575,7 +578,7 @@ def _serialize_for_transformers(
                 "user": [self.user],
                 "assistant": [self.callback_user],
             }
-        return super()._serialize_for_transformers(role_names, default_role, custom_serializer)
+        return super()._serialize_for_transformers(messages, role_names, default_role, custom_serializer)
 
     @param.depends("_callback_state", watch=True)
     async def _update_input_disabled(self):

panel/tests/chat/test_feed.py

@@ -824,6 +824,16 @@ def custom_serializer(obj):
         with pytest.raises(ValueError, match="must return a string"):
             chat_feed.serialize(custom_serializer=custom_serializer)
 
+    def test_serialize_filter_by(self, chat_feed):
+        def filter_by_reactions(messages):
+            return [obj for obj in messages if "favorite" in obj.reactions]
+
+        chat_feed.send(ChatMessage("no"))
+        chat_feed.send(ChatMessage("yes", reactions=["favorite"]))
+        filtered = chat_feed.serialize(filter_by=filter_by_reactions)
+        assert len(filtered) == 1
+        assert filtered[0]["content"] == "yes"
+
 
 @pytest.mark.xdist_group("chat")
 class TestChatFeedSerializeBase: