Custom Django field for easy use of markup in text fields
An implementation of a custom MarkupField for Django. A MarkupField is in essence a TextField with an associated markup type. The field also caches its rendered value on the assumption that disk space is cheaper than CPU cycles in a web application.
The recommended way to install django-markupfield is with pip
It is not necessary to add 'markupfield' to your INSTALLED_APPS, it merely needs to be on your PYTHONPATH.
django-markupfield depends on a relatively current version of Django (tested with 1.3-1.4, may work with 1.2 but not guaranteed) and libraries for whichever markup options you wish to include.
To best make use of MarkupField you should define the MARKUP_FIELD_TYPES setting, a mapping of strings to callables that ‘render’ a markup type:
import markdown from docutils.core import publish_parts def render_rest(markup): parts = publish_parts(source=markup, writer_name="html4css1") return parts["fragment"] MARKUP_FIELD_TYPES = ( ('markdown', markdown.markdown), ('ReST', render_rest), )
If you do not define a MARKUP_FIELD_TYPES then one is provided with the following markup types available:
- allows HTML, potentially unsafe
- plain text markup, calls urlize and replaces text with linebreaks
- default markdown renderer (only if python-markdown is installed)
- default ReST renderer (only if docutils is installed)
- default textile renderer (only if textile is installed)
It is also possible to override MARKUP_FIELD_TYPES on a per-field basis by passing the markup_choices option to a MarkupField in your model declaration.
Using MarkupField is relatively easy, it can be used in any model definition:
from django.db import models from markupfield.fields import MarkupField class Article(models.Model): title = models.CharField(max_length=100) slug = models.SlugField(max_length=100) body = MarkupField()
Article objects can then be created with any markup type defined in MARKUP_FIELD_TYPES:
Article.objects.create(title='some article', slug='some-article', body='*fancy*', body_markup_type='markdown')
You will notice that a field named body_markup_type exists that you did not declare, MarkupField actually creates two extra fields here body_markup_type and _body_rendered. These fields are always named according to the name of the declared MarkupField.
MarkupField also takes three optional arguments. Either default_markup_type and markup_type arguments may be specified but not both.
- Set a markup_type that the field will default to if one is not specified. It is still possible to edit the markup type attribute and it will appear by default in ModelForms.
- Set markup type that the field will always use, editable=False is set on the hidden field so it is not shown in ModelForms.
- A replacement list of markup choices to be used in lieu of MARKUP_FIELD_TYPES on a per-field basis.
- A flag (False by default) indicating that the input should be regarded as untrusted and as such will be run through Django’s escape filter.
MarkupField that will default to using markdown but allow the user a choice:
MarkupField that will use textile and not provide a choice on forms:
MarkupField that will use a custom set of renderers:
CUSTOM_RENDERERS = ( ('markdown', markdown.markdown), ('wiki', my_wiki_render_func) ) MarkupField(markup_choices=CUSTOM_RENDERERS)
Accessing a MarkupField on a model
When accessing an attribute of a model that was declared as a MarkupField a special Markup object is returned. The Markup object has three parameters:
- The unrendered markup.
- The markup type.
- The rendered HTML version of raw, this attribute is read-only.
This object has a __unicode__ method that calls django.utils.safestring.mark_safe on rendered allowing MarkupField objects to appear in templates as their rendered selfs without any template tag or having to access rendered directly.
Assuming the Article model above:
>>> a = Article.objects.all() >>> a.body.raw u'*fancy*' >>> a.body.markup_type u'markdown' >>> a.body.rendered u'<p><em>fancy</em></p>' >>> print unicode(a.body) <p><em>fancy</em></p>
Assignment to a.body is equivalent to assignment to a.body.raw and assignment to a.body_markup_type is equivalent to assignment to a.body.markup_type.
a.body.rendered is only updated when a.save() is called