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Customblocks for Markdown

CI Coverage PyPi license: AGPL v3 downloads

Customblocks is an extension for Python-Markdown that settles a common markup for parametrizable and nestable components whose output can be redefined by means of a simple Python function.

Many off-the-shelf components are provided such as div-containers, admonitions, figures, link cards, maps... and some embeded widgets from common sites (wikipedia, youtube, vimeo, peertube, mastodon, twitter, facebook, instagram, goteo, verkami...)

It also includes convenience tools to ease component definition: hyperscript html generation, cached page fetching and metadata page extraction.

Installation and setup

To install:

$ pip install markdown-customblocks

And then activate it as any other Markdown extension.

From command line:

$ markdown -x customblocks ...

In Python code:

import markdown
md = markdown.Markdown(extensions=["customblocks"])

In Pelican config:

    'extensions': [

For MkDocs, add this to mkdocs.yml:

  - customblocks

If you need to specify additional parameters for the extension, refer to the documentation of your generator.

Basic usage

Customblocks extension parses markup structures like this one:

::: mytype "value 1" param2=value2
    Indented **content**

And, by default, generates HTML like this:

<div class="mytype value-1" param2="value2">
   <p>Indented <b>content</b></p>

This is the output of the default generator: container. But we could bound mytype to a custom Python function like the following one:

def mygenerator(ctx, param1, param2):
    return f"""<div attrib1="{param1}" attrib2="{param2}">{ctx.content}</div>"""

And then, previous Markdown would generate this other HTML:

<div attrib1="value 1" attrib2="value2">Indented **content**</div>

Notice that this function is not escaping any received value and is not converting anything in the content to Markdown. Luckily, customblocks provides some useful tools for that: the hyperscript generator and the Markdown subparser:

from customblocks.utils import E, Markdown

def mygenerator(ctx, param1, param2):
    return E('', attrib1=param1, attrib2=param2,
        Markdown(ctx.content, ctx.parser)

You can read more about them at the related documentation.

Built-in generators

For convenience, customblocks also provides the following predefined generators:

  • container: A div element with arbitrary classes, attributes and content. This is the default when no type matches.
  • admonition: Admonitions, boxes for notes, warnings... (quite similar to the standard extra extension). It is bound to types note, info, error, warning....
  • figure: Full featured figures with captions, lightbox...
  • map: Maps from
  • linkcard: External link cards (like Facebook and Twitter do, when you post a link)
  • wikipedia: Wikipedia article card by lemma (and language)
  • youtube: Embeded videos from youtube.
  • vimeo: Embeded videos from vimeo.
  • peertube: Embeded videos from peertube
  • mastodon: Embeded mastodon posts
  • twitter: Embeded tweets
  • facebook: Embeded post from facebook
  • instagram: Embeded post from instagram
  • verkami: Fund raising project widget in [Verkami]
  • goteo: Fund raising project widget in [Goteo]

General markup syntax

This is a more complete example of markup:

::: mytype param1 key1=value1 "other param" key2='value2 with words' flag1 noflag2
    Indented **content**

    The block ends whenever the indentation stops
This unindented line is not considered part of the block

The headline: The line starting with ::: is the headline. It specifies, first, the block type (mytype) followed by a set of values that will be passed to the generator as parameters.

Block type: The type is used to select the generator function. If there is no generator bound to the type, the div-container generator, will be used by default.

Quotes: Muti-word values can be passed by using either single or double quotes. You can skip quotes if your value is single worded.

Explicit keywords: Also some values may target an explicit parameter with a key. This works as follows: from the available block parameters, values with a key are set first, then the remaining unset parameters are filled by position.

Flags (bools): Boolean parameters (flags) can be set by just adding a value with the name of the flag, like flag1 in the example. And they can be unset by adding the name with a no prefix, like noflag2 in the example.

Content: After the headline, several lines of indented content may follow. The content ends with the very first non-emtpy line back on the previous indentation.

Indentation is removed from the content for the generator to process it. A block type may choose to interpret this content as markdown as well. So you can have nested blocks by adding extra indentation. For example:

::: recipe
    # Sweet water
    ::: ingredients "4 persons"
        - two spons of suggar
        - a glass of tap water
    ::: mealphoto sweetwater.jpg
        Looks gorgeus!
    Drop the suggar into the glass. Stir.


A closing ::: tag is optional. For most cases, indentation should be enough, visually, and functionally. But, seldomly, it is necessary. Like in the example below, where the mealphoto content would be mixed with the later code block

::: mealphoto sweetwater.jpg
        Looks gorgeus!
        This is a code block by indentation

Further reading