support config sections (#29)

CHANGES.md

@@ -9,6 +9,8 @@ Unreleased
 - The constructor args `run_mkdir` and `command_name` are keyword only. {pr}`27`
 - Deprecate the `init_app` args `run_mkdir` and `command_name`. They can be
   passed to the constructor instead. {pr}`27`
+- Dict values in the `ALEMBIC` config are treated as Alembic config sections,
+  allowing use of Alembic features like `post_write_hooks`. {pr}`28`
 
 ## Version 3.0.1
 

docs/config.md

@@ -3,13 +3,20 @@
 Configuration for Alembic and its migrations uses the following Flask config
 keys.
 
-```{module} flask_alembic.config
+```{currentmodule} flask_alembic
 ```
 
 ```{data} ALEMBIC
 A dictionary containing general configuration, mostly used by
 {class}`~alembic.config.Config` and {class}`~alembic.script.ScriptDirectory`.
 See Alembic's docs on [config][alembic-config].
+
+If a value is a dict, the key will be equivalent to a section name in
+``alembic.ini``, and the value will be the items in the section. This allows
+using Alembic's [post_write_hooks], for example.
+
+.. versionchanged:: 3.1
+    Treat dict values as sections.
 ```
 
 ```{data} ALEMBIC_CONTEXT
@@ -28,3 +35,79 @@ otherwise default to `False` in Alembic.
 
 [alembic-config]: https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
 [alembic-runtime]: https://alembic.sqlalchemy.org/en/latest/api/runtime.html#runtime-objects
+[post_write_hooks]: https://alembic.sqlalchemy.org/en/latest/autogenerate.html#applying-post-processing-and-python-code-formatters-to-generated-revisions
+
+## Post Processing Revisions
+
+It's possible to tell Alembic to run one or more commands on a generated
+migration file. See [Alembic's docs][post_write_hooks] for full details.
+Here are some useful examples.
+
+### black
+
+Run the [black] formatter.
+
+[black]: https://black.readthedocs.io
+
+```python
+ALEMBIC = {
+    "post_write_hooks": {
+        "hooks": "black",
+        "pre-commit.type": "console_scripts",
+        "pre-commit.entrypoint": "black",
+    }
+}
+```
+
+### ruff
+
+Run the [ruff] formatter.
+
+[ruff]: https://docs.astral.sh/ruff/formatter/
+
+```python
+ALEMBIC = {
+    "post_write_hooks": {
+        "hooks": "ruff",
+        "pre-commit.type": "console_scripts",
+        "pre-commit.entrypoint": "ruff",
+        "pre-commit.options": "format REVISION_SCRIPT_FILENAME",
+    }
+}
+```
+
+### pre-commit
+
+Run all configured [pre-commit] hooks.
+
+[pre-commit]: https://pre-commit.com
+
+```python
+ALEMBIC = {
+    "post_write_hooks": {
+        "hooks": "pre-commit",
+        "pre-commit.type": "console_scripts",
+        "pre-commit.entrypoint": "pre-commit",
+        "pre-commit.options": "run --files REVISION_SCRIPT_FILENAME",
+    }
+}
+```
+
+### git add
+
+Add the file to git so that you don't forget when committing. This can be run
+after other hooks so that all the changes are staged.
+
+```python
+ALEMBIC = {
+    "post_write_hooks": {
+        "hooks": "pre-commit, git",
+        "pre-commit.type": "console_scripts",
+        "pre-commit.entrypoint": "pre-commit",
+        "pre-commit.options": "run --files REVISION_SCRIPT_FILENAME",
+        "git.type": "exec",
+        "git.executable": "git",
+        "git.options": "add REVISION_SCRIPT_FILENAME",
+    }
+}
+```

src/flask_alembic/extension.py

@@ -208,38 +208,41 @@ def config(self) -> Config:
         """
         cache = self._get_cache()
 
-        if cache.config is None:
-            cache.config = c = Config()
+        if cache.config is not None:
+            return cache.config
 
-            script_location = current_app.config["ALEMBIC"]["script_location"]
+        cache.config = c = Config()
+        script_location = current_app.config["ALEMBIC"]["script_location"]
 
-            if not os.path.isabs(script_location) and ":" not in script_location:
-                script_location = os.path.join(current_app.root_path, script_location)
+        if not os.path.isabs(script_location) and ":" not in script_location:
+            script_location = os.path.join(current_app.root_path, script_location)
 
-            version_locations = [script_location]
+        version_locations = [script_location]
 
-            for item in current_app.config["ALEMBIC"]["version_locations"]:
-                version_location = item if isinstance(item, str) else item[1]
+        for item in current_app.config["ALEMBIC"]["version_locations"]:
+            version_location = item if isinstance(item, str) else item[1]
 
-                if not os.path.isabs(version_location) and ":" not in version_location:
-                    version_location = os.path.join(
-                        current_app.root_path, version_location
-                    )
+            if not os.path.isabs(version_location) and ":" not in version_location:
+                version_location = os.path.join(current_app.root_path, version_location)
 
-                version_locations.append(version_location)
+            version_locations.append(version_location)
 
-            c.set_main_option("script_location", script_location)
-            c.set_main_option("version_locations", ",".join(version_locations))
+        c.set_main_option("script_location", script_location)
+        c.set_main_option("version_locations", ",".join(version_locations))
 
-            for key, value in current_app.config["ALEMBIC"].items():
-                if key in ("script_location", "version_locations"):
-                    continue
+        for key, value in current_app.config["ALEMBIC"].items():
+            if key in ("script_location", "version_locations"):
+                continue
 
+            if isinstance(value, dict):
+                for inner_key, inner_value in value.items():
+                    c.set_section_option(key, inner_key, inner_value)
+            else:
                 c.set_main_option(key, value)
 
-            if len(self.metadatas) > 1:
-                # Add the names used by the multidb template.
-                c.set_main_option("databases", ", ".join(self.metadatas))
+        if len(self.metadatas) > 1:
+            # Add the names used by the multidb template.
+            c.set_main_option("databases", ", ".join(self.metadatas))
 
         return cache.config