django-markupfield

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.

Installation

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. However, to use titled markup you either add 'markupfield' to your INSTALLED_APPS or add the corresponding translations to your project translation.

Requirements

Requires Django >= 2.2 and 3.6+

1.5.x is the last release to officially support Django < 2.2 or Python 2.7
1.4.x is the last release to officially support Django < 1.11
1.3.x is the last release to officially support Django 1.4 or Python 3.3

Settings

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:

html:: allows HTML, potentially unsafe
plain:: plain text markup, calls urlize and replaces text with linebreaks
markdown:: default markdown renderer (only if markdown is installed)
restructuredtext:: default ReST renderer (only if docutils 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.

Usage

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.

Arguments

MarkupField also takes three optional arguments. Either default_markup_type and markup_type arguments may be specified but not both.

default_markup_type:: 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.
markup_type:: Set markup type that the field will always use, editable=False is set on the hidden field so it is not shown in ModelForms.
markup_choices:: A replacement list of markup choices to be used in lieu of MARKUP_FIELD_TYPES on a per-field basis.
escape_html:: 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.

Examples

MarkupField that will default to using markdown but allow the user a choice:

MarkupField(default_markup_type='markdown')

MarkupField that will use ReST and not provide a choice on forms:

MarkupField(markup_type='restructuredtext')

MarkupField that will use a custom set of renderers:

CUSTOM_RENDERERS = (
    ('markdown', markdown.markdown),
    ('wiki', my_wiki_render_func)
)
MarkupField(markup_choices=CUSTOM_RENDERERS)

Note

When using markdown, be sure to use markdown.markdown and not the markdown.Markdown class, the class requires an explicit reset to function properly in some cases. (See [issue #40](#40) for details.)

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:

raw:: The unrendered markup.
markup_type:: The markup type.
rendered:: 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()[0]
>>> 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.

Important

Keeping in mind that body is MarkupField instance is particullary important with default or default_if_none filter for model that could be blank. If body's rendered is None or empty string ("") these filters will not evaluate body as falsy to display default text:

{{ a.body|default:"<missing body>" }}

That's because body is regular non-None MarkupField instance. To let default or default_if_none filters to work evaluate rendered MarkupField attribute instead. To prevent escaping HTML for the case rendered is truethy, finish chain with safe filter:

{{ a.body.rendered|default:"<missing body>"|safe }}