New feature: retrieve and update the PEP 621 project version, if poss…

…ible

When determining the current version, and if
`tool.bumpversion.current_version` is not set, attempt to retrieve the
version from `project.version` à la PEP 621. If that setting is not
set, or if the version is explicitly marked as dynamically set, then
continue with querying SCM tags.

When updating the configuration during bumping, if we previously
successfully retrieved a PEP 621 version, then update the
`project.version` field in `pyproject.toml` as well. We always update,
even if the true current version was read from
`tool.bumpversion.current_version` instead of `project.version`.

The docs have been updated; specifically, the "multiple replacements in
one file" howto and the reference for `current_version`.

The tests have been adapted: the new `pep621_info` property would
otherwise trip up the old test output, and the `None` default would trip
up the TOML serializer. Additionally, new tests assert that
`project.version` (and correspondingly, the `pep621_info` property) is
correctly honored or ignored, depending on the other circumstances.

bumpversion/config/__init__.py

@@ -4,7 +4,7 @@
 
 from typing import TYPE_CHECKING, Any, Optional
 
-from bumpversion.config.files import read_config_file
+from bumpversion.config.files import get_pep621_info, read_config_file
 from bumpversion.config.models import Config
 from bumpversion.exceptions import ConfigurationError
 from bumpversion.ui import get_indented_logger
@@ -32,6 +32,7 @@
     "message": "Bump version: {current_version} → {new_version}",
     "moveable_tags": [],
     "commit_args": None,
+    "pep621_info": None,
     "scm_info": None,
     "parts": {},
     "files": [],
@@ -84,6 +85,10 @@ def get_configuration(config_file: Optional[Pathlike] = None, **overrides: Any)
     Config.model_rebuild()
     config = Config(**config_dict)  # type: ignore[arg-type]
 
+    # Get the PEP 621 project.version key from pyproject.toml, if possible
+    config.pep621_info = get_pep621_info(config_file)
+    logger.debug("config.pep621_info = %r", config.pep621_info)
+
     # Get the information about the SCM
     scm_info = SCMInfo(SCMConfig.from_config(config))
     config.scm_info = scm_info
@@ -113,9 +118,12 @@ def check_current_version(config: Config) -> str:
         ConfigurationError: If it can't find the current version
     """
     current_version = config.current_version
+    pep621_info = config.pep621_info
     scm_info = config.scm_info
 
-    if current_version is None and scm_info.current_version:
+    if current_version is None and pep621_info is not None and pep621_info.version:
+        return pep621_info.version
+    elif current_version is None and scm_info.current_version:
         return scm_info.current_version
     elif current_version and scm_info.current_version and current_version != scm_info.current_version:
         logger.warning(

bumpversion/config/create.py

@@ -71,6 +71,7 @@ def get_defaults_from_dest(destination: str) -> Tuple[dict, TOMLDocument]:
     project_config = destination_config.get("project", {}).get("version")
     config["current_version"] = config["current_version"] or project_config or "0.1.0"
     del config["scm_info"]
+    del config["pep621_info"]
     del config["parts"]
     del config["files"]
 

bumpversion/config/files.py

@@ -6,6 +6,7 @@
 from typing import TYPE_CHECKING, Any, Dict, MutableMapping, Optional, Union
 
 from bumpversion.config.files_legacy import read_ini_file
+from bumpversion.config.models import PEP621Info
 from bumpversion.ui import get_indented_logger, print_warning
 
 if TYPE_CHECKING:  # pragma: no-coverage
@@ -23,6 +24,42 @@
 )
 
 
+def get_pep621_info(config_file: Optional[Pathlike] = None) -> Optional[PEP621Info]:
+    """Retrieve the PEP 621 `project` table.
+
+    At the moment, only the `project.version` key is handled. Additionally, if the
+    version is marked as dynamic, then it is explicitly returned as `None`.
+
+    Args:
+        config_file:
+            The configuration file to explicitly use. Per PEP 621, this file must be
+            named `pyproject.toml`.
+
+    Returns:
+        A `PEP621Info` structure, if given a `pyproject.toml` file to parse, else `None`.
+
+    """
+    # We repeat the steps of read_config_file here, except hardcoded to TOML files, and
+    # without additional error reporting.  Then we reimplement read_toml_file, but
+    # without limiting ourselves to the tool.bumpversion subtable.
+    if not config_file:
+        return None
+
+    config_path = Path(config_file)
+    if not config_path.exists():
+        return None
+
+    # PEP 621 explicitly requires pyproject.toml
+    if config_path.name != "pyproject.toml":
+        return None
+
+    import tomlkit
+
+    toml_data = tomlkit.parse(config_path.read_text(encoding="utf-8")).unwrap()
+    project = toml_data.get("project", {})
+    return PEP621Info(version=None if "version" in project.get("dynamic", []) else project.get("version"))
+
+
 def find_config_file(explicit_file: Optional[Pathlike] = None) -> Union[Path, None]:
     """
     Find the configuration file, if it exists.
@@ -139,7 +176,8 @@ def update_config_file(
         logger.info("You must have a `.toml` suffix to update the config file: %s.", config_path)
         return
 
-    # TODO: Eventually this should be transformed into another default "files_to_modify" entry
+    # TODO: Eventually this config (and datafile_config_pyprojecttoml below) should be
+    # transformed into another default "files_to_modify" entry
     datafile_config = FileChange(
         filename=str(config_path),
         key_path="tool.bumpversion.current_version",
@@ -154,4 +192,26 @@ def update_config_file(
 
     updater = DataFileUpdater(datafile_config, config.version_config.part_configs)
     updater.update_file(current_version, new_version, context, dry_run)
+
+    # Keep PEP 621 `project.version` consistent with `tool.bumpversion.current_version`.
+    # (At least, if PEP 621 static `project.version` is in use at all.)
+    if (
+        config_path.name == "pyproject.toml"
+        and config.pep621_info is not None
+        and config.pep621_info.version is not None
+    ):
+        datafile_config_pyprojecttoml = FileChange(
+            filename=str(config_path),
+            key_path="project.version",
+            search=config.search,
+            replace=config.replace,
+            regex=config.regex,
+            ignore_missing_version=True,
+            ignore_missing_file=True,
+            serialize=config.serialize,
+            parse=config.parse,
+        )
+        updater2 = DataFileUpdater(datafile_config_pyprojecttoml, config.version_config.part_configs)
+        updater2.update_file(current_version, new_version, context, dry_run)
+
     logger.dedent()

bumpversion/config/models.py

@@ -4,6 +4,7 @@
 
 import re
 from collections import defaultdict
+from dataclasses import dataclass
 from itertools import chain
 from typing import TYPE_CHECKING, Dict, List, MutableMapping, Optional, Tuple, Union
 
@@ -97,6 +98,7 @@ class Config(BaseSettings):
     commit: bool
     message: str
     commit_args: Optional[str]
+    pep621_info: Optional[PEP621Info]
     scm_info: Optional[SCMInfo]
     parts: Dict[str, VersionComponentSpec]
     moveable_tags: list[str] = Field(default_factory=list)
@@ -179,3 +181,10 @@ def version_spec(self, version: Optional[str] = None) -> "VersionSpec":
         from bumpversion.versioning.models import VersionSpec
 
         return VersionSpec(self.parts)
+
+
+@dataclass
+class PEP621Info:
+    """PEP 621 info, in particular, the static version number."""
+
+    version: Optional[str]

docs/howtos/multiple-replacements.md

@@ -18,3 +18,7 @@ filename = "CHANGELOG.md"
 search = "{current_version}...HEAD"
 replace = "{current_version}...{new_version}"
 ```
+
+??? note "Note: `project.version` in `pyproject.toml`"
+
+    This technique is **not** needed to keep `project.version` in `pyproject.toml` up-to-date if you are storing your Bump My Version configuration in `pyproject.toml` as well. Bump My Version will handle this case automatically.

docs/reference/configuration/global.md

@@ -80,7 +80,7 @@ If you have pre-commit hooks, add an option to turn off your pre-commit hooks. F
 ::: field-list
 
     required
-    : **Yes**
+    : **Yes‡**
 
     default
     : `""`
@@ -94,7 +94,11 @@ If you have pre-commit hooks, add an option to turn off your pre-commit hooks. F
     environment var
     : `BUMPVERSION_CURRENT_VERSION`
 
-The current version of the software package before bumping. A value for this is required.
+The current version of the software package before bumping. A value for this is required, unless a fallback value is found.
+
+!!! note
+
+    ‡ If `pyproject.toml` exists, then `current_version` falls back to `project.version` in `pyproject.toml`. This only works if `project.version` is statically set.
 
 ## ignore_missing_files
 

tests/fixtures/basic_cfg_expected.txt

@@ -79,6 +79,7 @@
                        'independent': False,
                        'optional_value': 'gamma',
                        'values': ['dev', 'gamma']}},
+ 'pep621_info': {'version': None},
  'post_commit_hooks': [],
  'pre_commit_hooks': [],
  'regex': False,

tests/fixtures/basic_cfg_expected.yaml

@@ -108,6 +108,8 @@ parts:
     values:
       - "dev"
       - "gamma"
+pep621_info:
+  version: null
 post_commit_hooks:
 
 pre_commit_hooks:

tests/fixtures/basic_cfg_expected_full.json

@@ -122,6 +122,9 @@
       ]
     }
   },
+  "pep621_info": {
+    "version": null
+  },
   "post_commit_hooks": [],
   "pre_commit_hooks": [],
   "regex": false,