101 lines
3.6 KiB
Python
101 lines
3.6 KiB
Python
from typing import TYPE_CHECKING, List
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from django.forms.widgets import Media, MediaDefiningClass
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from django.template.loader import get_template
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from laces.typing import HasMediaProperty
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if TYPE_CHECKING:
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from typing import Optional
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from django.utils.safestring import SafeString
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from laces.typing import RenderContext
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class Component(metaclass=MediaDefiningClass):
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"""
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A class that knows how to render itself.
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Extracted from Wagtail. See:
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https://github.com/wagtail/wagtail/blob/094834909d5c4b48517fd2703eb1f6d386572ffa/wagtail/admin/ui/components.py#L8-L22 # noqa: E501
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A component uses the `MetaDefiningClass` metaclass to add a `media` property, which
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allows the definitions of CSS and JavaScript assets that are associated with the
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component. This works the same as `Media` class used by Django forms.
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See also: https://docs.djangoproject.com/en/4.2/topics/forms/media/
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"""
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template_name: str
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def render_html(
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self,
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parent_context: "Optional[RenderContext]" = None,
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) -> "SafeString":
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"""
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Return string representation of the object.
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Given a context dictionary from the calling template (which may be a
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`django.template.Context` object or a plain `dict` of context variables),
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returns the string representation to be rendered.
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This will be subject to Django's HTML escaping rules, so a return value
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consisting of HTML should typically be returned as a
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`django.utils.safestring.SafeString` instance.
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"""
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context_data = self.get_context_data(parent_context)
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template = get_template(self.template_name)
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return template.render(context_data)
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def get_context_data(
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self,
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parent_context: "Optional[RenderContext]" = None,
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) -> "Optional[RenderContext]":
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"""Return the context data to render this component with."""
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return {}
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# fmt: off
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if TYPE_CHECKING:
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# It's ugly, I know. But it seems to be the best way to make `mypy` happy.
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# The `media` property is dynamically added by the `MediaDefiningClass`
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# metaclass. Because of how dynamic it is, `mypy` is not able to pick it up.
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# This is why we need to add a type hint for it here. The other way would be a
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# stub, but that would require the whole module to be stubbed and that is even
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# more annoying to keep up to date.
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@property
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def media(self) -> Media: ... # noqa: E704
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# fmt: on
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class MediaContainer(List[HasMediaProperty]):
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"""
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A list that provides a `media` property that combines the media definitions
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of its members.
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Extracted from Wagtail. See:
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https://github.com/wagtail/wagtail/blob/ca8a87077b82e20397e5a5b80154d923995e6ca9/wagtail/admin/ui/components.py#L25-L36 # noqa: E501
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The `MediaContainer` functionality depends on the `django.forms.widgets.Media`
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class. The `Media` class provides the logic to combine the media definitions of
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multiple objects through its `__add__` method. The `MediaContainer` relies on this
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functionality to provide a `media` property that combines the media definitions of
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its members.
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See also:
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https://docs.djangoproject.com/en/4.2/topics/forms/media
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"""
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@property
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def media(self) -> Media:
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"""
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Return a `Media` object containing the media definitions of all members.
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This makes use of the `Media.__add__` method, which combines the media
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definitions of two `Media` objects.
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"""
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media = Media()
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for item in self:
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media += item.media
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return media
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