extensions

Goldmark Extensions

Goldmark Extensions is a collection of extensions for Goldmark.

Originally forked from yuin/goldmark-meta, this project has undergone breaking changes and now stands on its own.

Overview

Goldmark Extensions provides the following functions to extend Goldmark.

1. Scrape document metadata from YAML front matter defined at the top of a markdown document.
2. Aggregate a configurable-length snippet of the markdown documents text content.
3. Add attribute class="task" to tasklist items.

Installation

go get github.com/moyen-blog/goldmark-extensions

YAML Front Matter

Include the Goldmark extension with extensions.MetadataExtension.

Markdown Syntax

YAML front matter is metadata defined at the top of a markdown document. It can not contain markdown itself. The front matter block must be surrounded by lines containing the YAML metadata separator ---. If metadata is defined, the separator must be the first line of the document. The YAML metadata block must end with a YAML metadata separator.

All valid YAML is supported. The underlying parsing of YAML is done by go-yaml/yaml.

Example:

---
title: goldmark-extensions
tags:
  - one
---

# Heading 1

Accessing Metadata

The metadata can be parsed via the meta.Unmarshal() function.

import (
    "bytes"
    "fmt"
    "github.com/yuin/goldmark"
    "github.com/yuin/goldmark/parser"
    extensions "github.com/moyen-blog/goldmark-extensions"
)

func main() {
    markdown := goldmark.New(
        goldmark.WithExtensions(
            extensions.MetadataExtension,
        ),
    )
    source := `---
title: goldmark-extensions
summary: Add YAML metadata to the document
tags:
  - one
---

# Hello goldmark-extensions
`

    var buf bytes.Buffer
    context := parser.NewContext()
    if err := markdown.Convert([]byte(source), &buf, parser.WithContext(context)); err != nil {
        panic(err)
    }
    // Note: Struct fields must be public in order to correctly populate the data
    out := struct {
        Title string
        Tags []string
    }{}
    if err := extensions.Unmarshal(context, &out); err != nil {
        panic(err)
    }
    fmt.Println(out.Title, out.Tags)
}

Markdown Text Snippet

Include the Goldmark extension with extensions.SnippetExtension(max) where max is the maximum length of the generated snippet.

Markdown Syntax

There is no specific syntax needed for generating a text snippet. The snippet is made up of text from paragraphs within the markdown document only.

Example:

# Heading 1

Here's some text in a paragraph.

# Heading 2

More text here.

Accessing Text Snippet

The generated snippet is accessed via the extensions.Snippet() function.

import (
    "bytes"
    "fmt"
    "github.com/yuin/goldmark"
    "github.com/yuin/goldmark/parser"
    extensions "github.com/moyen-blog/goldmark-extensions"
)

func main() {
    var markdown = goldmark.New(
        goldmark.WithExtensions(
            extensions.SnippetExtension(100), // Maximum length of snippet
        ),
    )
    source := `# Hello
Paragraph text here.

Another one.
And continued here.`

    var buf bytes.Buffer
    context := parser.NewContext()
    if err := markdown.Convert([]byte(source), &buf, parser.WithContext(context)); err != nil {
        panic(err)
    }
    s, err := extensions.Snippet(context)
    if err != nil {
        panic(err)
    }
    fmt.Println(s)
}

Tasklist Styling

Include the Goldmark extension with extensions.TasklistExtension. This extension relies on the built-in Goldmark tasklist extension.

Markdown Syntax

Standard tasklist markdown syntax applies. With the class applied, further styling can be applied specifically to tasklist items while leaving standard list items unaffected e.g. li.task.

Example:

# Markdown Tasklist

Here's my list:
- [ ] Unchecked task
- Plaintext list item
- [ ] Checked task

In the previous example, only the first and third items will have class="task" inline styling applied.