The form rendering API

Django's form widgets are rendered using Django's template engines system.

The form rendering process can be customized at several levels:

  • Widgets can specify custom template names.
  • Forms and widgets can specify custom renderer classes.
  • A widget's template can be overridden by a project. (Reusable applications typically shouldn't override built-in templates because they might conflict with a project's custom templates.)

The low-level render API

The rendering of form templates is controlled by a customizable renderer class. A custom renderer can be specified by updating the FORM_RENDERER setting. It defaults to 'django.forms.renderers.DjangoTemplates'.

You can also provide a custom renderer by setting the Form.default_renderer attribute or by using the renderer argument of Widget.render().

Use one of the built-in template form renderers or implement your own. Custom renderers must implement a render(template_name, context, request=None) method. It should return a rendered templates (as a string) or raise TemplateDoesNotExist.

Built-in-template form renderers

DjangoTemplates

class DjangoTemplates[源代码]

This renderer uses a standalone DjangoTemplates engine (unconnected to what you might have configured in the TEMPLATES setting). It loads templates first from the built-in form templates directory in django/forms/templates and then from the installed apps' templates directories using the app_directories loader.

If you want to render templates with customizations from your TEMPLATES setting, such as context processors for example, use the TemplatesSetting renderer.

Jinja2

class Jinja2[源代码]

This renderer is the same as the DjangoTemplates renderer except that it uses a Jinja2 backend. Templates for the built-in widgets are located in django/forms/jinja2 and installed apps can provide templates in a jinja2 directory.

To use this backend, all the widgets in your project and its third-party apps must have Jinja2 templates. Unless you provide your own Jinja2 templates for widgets that don't have any, you can't use this renderer. For example, django.contrib.admin doesn't include Jinja2 templates for its widgets due to their usage of Django template tags.

TemplatesSetting

class TemplatesSetting[源代码]

This renderer gives you complete control of how widget templates are sourced. It uses get_template() to find widget templates based on what's configured in the TEMPLATES setting.

Using this renderer along with the built-in widget templates requires either:

  • 'django.forms' in INSTALLED_APPS and at least one engine with APP_DIRS=True.

  • Adding the built-in widgets templates directory in DIRS of one of your template engines. To generate that path:

    import django
django.__path__[0] + '/forms/templates'  # or '/forms/jinja2'

Using this renderer requires you to make sure the form templates your project needs can be located.

Context available in widget templates

Widget templates receive a context from Widget.get_context(). By default, widgets receive a single value in the context, widget. This is a dictionary that contains values like:

  • name
  • value
  • attrs
  • is_hidden
  • template_name

Some widgets add further information to the context. For instance, all widgets that subclass Input defines widget['type'] and MultiWidget defines widget['subwidgets'] for looping purposes.

Overriding built-in widget templates

Each widget has a template_name attribute with a value such as input.html. Built-in widget templates are stored in the django/forms/widgets path. You can provide a custom template for input.html by defining django/forms/widgets/input.html, for example. See Built-in widgets for the name of each widget's template.

To override widget templates, you must use the TemplatesSetting renderer. Then overriding widget templates works the same as overriding any other template in your project.

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