Handlers¤

A handler is what makes it possible to collect and render documentation for a particular language.

Available handlers¤

About the Python handlers¤

Since version 0.18, a new, experimental Python handler is available. It is based on Griffe, which is an improved version of pytkdocs.

Note that the experimental handler does not yet support third-party libraries like Django, Marshmallow, Pydantic, etc. It is also not completely ready to handle dynamically built objects, like classes built with a call to type(...). For most other cases, the experimental handler will work just fine.

If you want to keep using the legacy handler as long as possible, you can depend on mkdocstrings-python-legacy directly, or specify the python-legacy extra when depending on mkdocstrings:

pyproject.toml

# PEP 621 dependencies declaration
# adapt to your dependencies manager
[project]
dependencies = [
    "mkdocstrings[python-legacy]>=0.18",
]

The legacy handler will continue to "work" for many releases, as long as the new handler does not cover all previous use-cases.

Migrate to the experimental Python handler¤

To use the new, experimental Python handler, you can depend on mkdocstrings-python directly, or specify the python extra when depending on mkdocstrings:

pyproject.toml

# PEP 621 dependencies declaration
# adapt to your dependencies manager
[project]
dependencies = [
    "mkdocstrings[python]>=0.18",
]

Handler options¤

setup_commands is not yet implemented. In most cases, you won't need it, since by default the new handler does not execute the code.

Selection options¤

Warning

Since mkdocstrings 0.19, the YAML selection key is merged into the options key.

filters is implemented, and used as before.
members is implemented, and used as before.
inherited_members is not yet implemented.
docstring_style is implemented, and used as before, except for the restructured-text style which is renamed sphinx. Numpy-style is now built-in, so you can stop depending on pytkdocs[numpy-style] or docstring_parser.
docstring_options is implemented, and used as before. Refer to the griffe documentation for the updated list of supported docstring options.
new_path_syntax is irrelevant now. If you were setting it to True, remove the option and replace every colon (:) in your autodoc identifiers by dots (.).

See all the handler's options.

Rendering options¤

Warning

Since mkdocstrings 0.19, the YAML rendering key is merged into the options key.

Every previous option is supported. Additional options are available:

separate_signature: Render the signature (or attribute value) in a code block below the heading, instead as inline code. Useful for long signatures. If Black is installed, the signature is formatted. Default: False.
line_length: The maximum line length to use when formatting signatures. Default: 60.
show_submodules: Whether to render submodules of a module when iterating on children. Default: False.
docstring_section_style: The style to use to render docstring sections such as attributes, parameters, etc. Available styles: table (default), list and spacy. The SpaCy style is a poor implementation of their table style. We are open to improvements through PRs!

See all the handler's options.

Templates¤

Templates are mostly the same as before, but the file layout has changed, as well as some file names. Here is the new tree:

📁 theme/
├── 📄 attribute.html
├── 📄 children.html
├── 📄 class.html
├── 📁 docstring/
│   ├── 📄 admonition.html
│   ├── 📄 attributes.html
│   ├── 📄 examples.html
│   ├── 📄 other_parameters.html
│   ├── 📄 parameters.html
│   ├── 📄 raises.html
│   ├── 📄 receives.html
│   ├── 📄 returns.html
│   ├── 📄 warns.html
│   └── 📄 yields.html
├── 📄 docstring.html
├── 📄 expression.html
├── 📄 function.html
├── 📄 labels.html
├── 📄 module.html
└── 📄 signature.html

See them in the handler repository. See the documentation about the Python handler templates: https://mkdocstrings.github.io/python/customization/#templates.

Custom handlers¤

Since version 0.14, you can create and use custom handlers thanks to namespace packages. For more information about namespace packages, see their documentation.

TL;DR - Project template for handlers

mkdocstrings provides a Copier template to kickstart new handlers: https://github.com/mkdocstrings/handler-template. To use it, install Copier (pipx install copier), then run copier gh:mkdocstrings/handler-template my_handler to generate a new project. See its upstream documentation to learn how to work on the generated project.

Packaging¤

For mkdocstrings, a custom handler package would have the following structure:

📁 your_repository
└─╴📁 mkdocstrings_handlers
   └─╴📁 custom_handler
      ├─╴📁 templates
      │  ├─╴📁 material
      │  ├─╴📁 mkdocs
      │  └─╴📁 readthedocs
      └─╴📄 __init__.py

Note the absence of __init__.py module in mkdocstrings_handlers!

Code¤

A handler is a subclass of the base handler provided by mkdocstrings.

See the documentation for the BaseHandler. Subclasses of the base handler must implement the collect and render methods at least. The collect method is responsible for collecting and returning data (extracting documentation from source code, loading introspecting objects in memory, other sources? etc.) while the render method is responsible for actually rendering the data to HTML, using the Jinja templates provided by your package.

You must implement a get_handler method at the module level. This function takes the following parameters:

theme (string, theme name)
custom_templates (optional string, path to custom templates directory)
config_file_path (optional string, path to the config file)

These arguments are all passed as keyword arguments, so you can ignore them by adding **kwargs or similar to your signature. You can also accept additional parameters: the handler's global-only options will be passed to this function when instantiating your handler.

Check out how the Python handler is written for inspiration.

Templates¤

Your handler's implementation should normally be backed by templates, which go to the directory mkdocstrings_handlers/custom_handler/templates/some_theme. (custom_handler here should be replaced with the actual name of your handler, and some_theme should be the name of an actual MkDocs theme that you support, e.g. material).

With that structure, you can use self.env.get_template("foo.html") inside your render method. This already chooses the subdirectory based on the current MkDocs theme.

If you wish to support any MkDocs theme, rather than a few specifically selected ones, you can pick one theme's subdirectory to be the fallback for when an unknown theme is encountered. Then you just need to set the fallback_theme variable on your handler subclass. The fallback directory can be used even for themes you explicitly support: you can omit some template from one of the other theme directories in case they're exactly the same as in the fallback theme.

If your theme's HTML requires CSS to go along with it, put it into a file named mkdocstrings_handlers/custom_handler/templates/some_theme/style.css, then this will be included into the final site automatically if this handler is ever used. Alternatively, you can put the CSS as a string into the extra_css variable of your renderer.

Finally, it's possible to entirely omit templates, and tell mkdocstrings to use the templates of another handler. In you handler, override the get_templates_dir() method to return the other handlers templates path:

from pathlib import Path
from mkdocstrings.handlers.base import BaseHandler


class CobraHandler(BaseHandler):
    def get_templates_dir(self, handler: str) -> Path:
        # use the python handler templates
        # (it assumes the python handler is installed)
        return super().get_templates_dir("python")

Usage¤

When a custom handler is installed, it is then available to mkdocstrings. You can configure it as usual:

mkdocs.yml

plugins:
- mkdocstrings:
    handlers:
      custom_handler:
        handler_config_option: yes
        options:
          some_config_option: "a"
          other_config_option: 0

...and use it in your autodoc instructions:

docs/some_page.md

# Documentation for an object

::: some.objects.path
    handler: custom_handler
    options:
      some_config_option: "b"
      other_config_option: 1