Batch Edit Yaml Front Matter

Edit front matter markdown files with Jinja2 templates.

Description:

This is a python3 (v3.5.3+) class/module that can be used for batch processing and
editing front matter in markdown files. Front matter is managed via
Jinja2 template processor.

Features:

Add / Update / Delete any front matter fields
Preserves front matter element order via oyaml
Uses Jinja2 Templates for configuration and processing:
- Use Jinja2 filters for complex processing
- Incrementally process files with multiple templates
Uses Exceptions around sensitive areas of code
Examples for implementation:
Documented with Sphinx and hosted on Github

Documentation:

Project Documentation with examples Page
Dev.to Article: Be a Python Jinja Master: Automated Front Matter Editing

Installation:

pip install editfrontmatter

Dependencies:

editfrontmatter>=0.0.1
Jinja2>=2.10.1
MarkupSafe>=1.1.1
oyaml>=0.9
PyYAML>=5.1

TL;DR Example Usage:

Original markdown file with yaml front matter (example1.md)

---
title: "EditFrontMatter Class Example 1"
description: "Edit some fields in this front matter"
catagories: [programming, python, markdown]

deleteme: this will be deleted

tags: [front matter, administration, testing]

# comments and spaces will be eliminated (see docs)

author: "Karl N. Redman"
creatordisplayname: "Karl N. Redman"
creatoremail: "karl.redman@example.com"
date: 2019-05-23T17:43:45-05:00
lastmodifierdisplayname: "Karl N. Redman"
lastmodifieremail: "karl.redman@gmail.com"
lastmod: 2019-05-23T17:43:45-05:00
toc: false
type: "page"
hasMath: false
draft: false
weight: 5
---

# EditFontMatter Class Example 1

Edit several fields of front matter.

## Fields affected in this example:

* toc
  * note: uses local template variable
  * pre: false
  * post: true
* draft:
  * note: uses jinja2 filter (callback)
  * pre: false
  * post: true
* hasMath
  * note: uses program variable
  * pre: true
  * post: false
* stuff:
  * note: uses program variable to create field
  * pre: did not exist
  * post: (list) ['one', 'two', 'three']
* deleteme:
  * note: removed from final result
  * pre: this will be deleted
  * post: N/A

Jinja2 template that will update the front matter data of the source markdown file (template1.j2)

{% set toc = "true" %}

toc: {{ toc }}
draft: {{ false | canPublish }}
hasMath: {{ hasMath }}
stuff: {{ addedVariable }}

Python program to edit the markdown file with the Jinja2 template (example1.py)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-


from editfrontmatter import EditFrontMatter
import os


def canPublish_func(val):
    # do some processing....
    return True


def main():

    # generic path - overridden by env var `TEST_DATA_DIR`
    DATA_PATH = "../data/"

    if "TEST_DATA_DIR" in os.environ:
        DATA_PATH = os.path.abspath(os.environ.get("TEST_DATA_DIR")) + "/"

    # set path to input file
    file_path = os.path.abspath(DATA_PATH + "example1.md")

    # initialize `template_str` with template file content
    template_str = ''.join(open(os.path.abspath(DATA_PATH + "template1.j2"), "r").readlines())
    print(template_str)

    # instantiate the processor
    proc = EditFrontMatter(file_path=file_path, template_str=template_str)

    # set fields to delete from yaml
    proc.keys_toDelete = ['deleteme']

    # add a filter and callback function
    proc.add_JinjaFilter('canPublish', canPublish_func)

    # populate variables and run processor
    proc.run({'toc': 'no effect', 'hasMath': "false",
              'addedVariable': ['one', 'two', 'three']})

    # dump file
    print(proc.dumpFileData())


if __name__ == '__main__':
    main()

Final Output:

---
title: EditFrontMatter Class Example 1
description: Edit some fields in this front matter
catagories:
- programming
- python
- markdown
tags:
- front matter
- administration
- testing
author: Karl N. Redman
creatordisplayname: Karl N. Redman
creatoremail: karl.redman@example.com
date: 2019-05-23 22:43:45
lastmodifierdisplayname: Karl N. Redman
lastmodifieremail: karl.redman@gmail.com
lastmod: 2019-05-23 22:43:45
toc: true
type: page
hasMath: false
draft: true
weight: 5
stuff:
- one
- two
- three
---

# EditFontMatter Class Example 1

Edit several fields of front matter.

## Fields affected in this example:

* toc
  * note: uses local template variable
  * pre: false
  * post: true
* draft:
  * note: uses jinja2 filter (callback)
  * pre: false
  * post: true
* hasMath
  * note: uses program variable
  * pre: true
  * post: false
* stuff:
  * note: uses program variable to create field
  * pre: did not exist
  * post: (list) ['one', 'two', 'three']
* deleteme:
  * note: removed from final result
  * pre: this will be deleted
  * post: N/A