Pandoc Reader

Pandoc Reader is a Pelican plugin that converts documents written in Pandoc's Markdown into HTML 5.

Prerequisites

The plugin has a number of dependencies:

• Python >= 3.7
• Pelican >= 4.5.1
• Pandoc >= 2.11.0
• PyYAML >= 5.3.1
• Markdown Word Count >= 0.0.1

All five must be installed locally on your machine or webserver.

To find out how to install Python please see here

To install Pandoc follow these instructions.

Pelican, PyYAML and the Markdown Word Count packages can be installed using pip as shown below:

pip install pelican
pip install PyYAML
pip install markdown-word-count

The plugin should function correctly on newer versions of the above dependencies as well.

Installation

To install the plugin execute the following command:

python -m pip install pelican-pandoc-reader

Usage

This plugin converts Pandoc's Markdown into HTML 5. Conversion from other flavours of Markdown is supported but requires the use of a default file as described here.

Converting to formats other than HTML 5 is not supported.

Specifying File Metadata

The plugin expects all Markdown files to start with a YAML block as shown below.

---
title: "<post-title>"
author: "<author-name>"
data: "<date>"
---

or

...
title: "<post-title>"
author: "<author-name>"
date: "<date>"
...

Note: The YAML block shown above is Pandoc's syntax for specifying file metadata. This is different to Pelican's format. You may need to be rewrite the metadata in your files, in Pelican's format, if you stop using this plugin.

YAML blocks that define more than one level, such as YAML lists are not supported, although, they are supported by Pandoc. This is due to metadata processing limitations. In cases where you would normally add a YAML list, use a comma separated string instead.

More information on Pandoc's YAML metadata blocks are available here.

Information about Pelican's predefined metadata is available here.

Specifying Pandoc Options

The plugin supports two mutually exclusive methods to pass options to Pandoc.

Method One: Using Settings in pelicanconf.py

The first method involves configuring two settings in your pelicanconf.py file:

• PANDOC_ARGS
• PANDOC_EXTENSIONS

In the PANDOC_ARGS parameter you may specify any argument supported by Pandoc as shown below:

PANDOC_ARGS = [
    '--mathjax'
    '--citeproc'
]

Then in the PANDOC_EXTENSIONS parameter you may enable/disable any number of the supported Pandoc extensions:

PANDOC_EXTENSIONS = [
    '+footnotes',  # Enabled extension
    '-pipe_tables' # Disabled extension
]

Method Two: Using Pandoc Default Files

The second method involves specifying the path(s) to one or more Pandoc default file(s), with all your preferences written in YAML format.

These paths should be set in your pelicanconf.py file by using the setting PANDOC_DEFAULT_FILES. The paths maybe absolute or relative but we recommend using relative paths as they are more portable.

PANDOC_DEFAULT_FILES = [
    '<path/to/default/file_one.yaml>',
    '<path/to/default/file_two.yaml>'
]

Here is a minimal example of content that should be available in a Pandoc default file:

reader: markdown
writer: html5

Using default files has the added benefit of allowing you to use other Markdown flavors supported by Pandoc such as, CommonMark and GitHub-Flavored Markdown.

Please see Pandoc Default files for a more complete example.

Note: In both methods specifying the arguments --standalone or --self-contained is not supported and will result in an error.

Generating a Table of Contents

If you desire to create a Table of Contents for posts or pages, you may do so by specifying the --toc or --table-of-contents argument in the PANDOC_ARGS setting as shown:

PANDOC_ARGS = [
    '--toc'
]

or

PANDOC_ARGS = [
    '--table-of-contents'
]

To set this in a Pandoc default file use the syntax below:

table-of-contents: true

The table of contents will be available for use in templates using the {{ article.toc }} or {{ page.toc }} Jinja template variables.

Enabling Citations

You may enable citations by specifying the citations extension and the -C or --citeproc option.

Set the PANDOC_ARGS and PANDOC_EXTENSIONS in pelicanconf.py as shown below:

PANDOC_ARGS = [
    '--citeproc'
]

or

PANDOC_ARGS = [
    '-C'
]

and

PANDOC_EXTENSIONS = [
    '+citations'
]

If you are using a Pandoc default file you need the following as a bare minimum to enable citations:

reader: markdown+citations
writer: html5

citeproc: true

Without these settings citations will not be processed by the plugin.

You may write your bibliography in any format supported by Pandoc with the appropriate extensions specified. However, you must name the bibliography file the same as your blog.

For example, a blog with the file name my-blog.md should have a bibliography file called my-blog.bib, my-blog.json, my-blog.yaml or my-blog.bibtex in the same directory as your blog, or in a subdirectory of the directory that your blog resides in. Failure to do so will mean that the references will not be picked up.

Known Issues with Citations

If enabling citations with a specific style, you need to specify a CSL (Citation Style Language) file, available from the Zotero Style Repository. For example, if you are using ieee-with-url style file it may be specified in your pelicanconf.py as shown:

PANDOC_ARGS = [
   '--csl=https://www.zotero.org/styles/ieee-with-url'
]

Or in a Pandoc default file like so:

csl: "https://www.zotero.org/styles/ieee-with-url"

Specifying a remote CSL file as shown above, dramatically increases the time taken to process the Markdown content.

To improve processing speed, it is highly recommended that you use a local copy of the CSL file downloaded from Zotero.

You may then reference it in pelicanconf.py as shown below:

PANDOC_ARGS = [
   '--csl=path/to/file/ieee-with-url.csl'
]

Or in a Pandoc default file like so:

csl: "path/to/file/ieee-with-url.csl"

Calculating and Displaying Reading Time

The plugin may be used to calculate the reading time of articles and pages by setting CALCULATE_READING_TIME to True in your pelicanconf.py file:

CALCULATE_READING_TIME = True

You may display the reading time using the {{ article.reading_time }} or {{ page.reading_time }} template variables. The unit of time will be displayed as minute for reading times less than or equal to one minute, or minutes for those greater than one minute.

The reading time is calculated by dividing the number of words by the reading speed which is the average number words read in a minute.

The default value for reading speed is set to 200 words per minute, but may be customized, by setting READING_SPEED to the desired words per minute value in pelicanconf.py:

READING_SPEED = <words-per-minute>

The number of words in a document is calculated using the Markdown Word Count python package.

Contributing

Contributions are welcome and much appreciated. Every little bit helps. You can contribute by improving the documentation, adding missing features, and fixing bugs. You can also help out by reviewing and commenting on existing issues.

To start contributing to this plugin, review the Contributing to Pelican documentation, beginning with the Contributing Code section.

Credits

Originally authored by Hinrich B. Winther in December 2014, which was subsequently forked and completely redesigned and rewritten by Nandakumar Chandrasekhar in October 2020.