Yaml Syntax Cheat Sheet



%YAML 1.1 # Reference card - Collection indicators: '? ': Key indicator. ': ': Value indicator. '- ': Nested series entry indicator. Jekyll Cheat Sheet. Page specific information + the YAML front matter. Custom variables set via the YAML Front Matter will be available here. Site Sitewide information + configuration settings from config.yml. Liquid filters - array Docs.

Yet Another Markup Language (YAML) is a way to create structured text and data—often used for generating websites and configuration.

Cheat

What’s the point of YAML

This Markdown cheat sheet provides a quick overview of all the Markdown syntax elements. It can’t cover every edge case, so if you need more information about any of these elements, refer to the reference guides for basic syntax and extended syntax. These are the elements outlined in John Gruber’s original design document. YAML stands for (YAML Ain’t Markup Language). It is a human friendly serialization language mainly used for configuration files. It can also be used for storing debugging output or document headers. It has a very limited syntax. It started with the reference as Yet another markup language, before it got the current YAML Ain’t Markup Language. YAML Syntax ¶ This page provides a basic overview of correct YAML syntax, which is how Ansible playbooks (our configuration management language) are expressed. We use YAML because it is easier for humans to read and write than other common data formats like XML or JSON.

YAML’s simple structure is great work creating ☛ content templates and for making systems of website generation.

When using a system like ☛ Jekyll, YAML can bet used for extra metadata about the document that isn’t part of the main content, that can be used in different places.

A couple examples:

Indent with spaces

YAML is really strict about this: indent with 2 spaces only.

Structured data

YAML is for structuring data and information using systems like objects and arrays from programming languages.

The data of YAML has two main structures:

  • objects: like <dl> elements in HTML, or {} objects in JavaScript
  • arrays: like <ul> elements in HTML, or [] arrays in JavaScript

Objects

Objects in YAML are started with a word/term followed by a colon and space. You make up the term so that it suits your data.

We can have as many items in the object as we want:

We can even have objects inside other objects, just by starting a new term:

Arrays

Arrays are just a big list or collection, each item starting with a dash. They keep their order when output in systems.

Above you can see that the array is inside an object. But it can be the other way around too, objects inside arrays:

Text blocks

If you have super large text blocks in your YAML, you can use vertical pipes (|) or greater than symbols (>) to separate the text out and allow a little more formatting.

Greater than

The greater than symbol allows you to write your text on multiple lines, knowing that when your YAML is parsed those lines will be collapsed into a single line.

Vertical pipe

The vertical pipe allows you to write your text on multiple lines, knowing that those multiple lines will be kept when the YAML is parsed.

The vertical pipe is really great for embedding code samples in YAML:

Escaping information

Sometimes YAML can get confused between content and structure—like for instance when using ampersands. If that’s the case, we can wrap the content in quotes to escape it.

Markdown front matter

We use Markdown for structuring our content, but sometimes you want to add more structured data to your Markdown that just the default formatting. This can be accomplished with YAML front matter.

At the top of your Markdown document, you put a series of three double dashes and provide more data between them:

This data can then be used in lots of applications, including Jekyll.

Video list

Supplemental links

DocFX supports DocFX Flavored Markdown, aka DFM. It supports all GitHub Flavored Markdown syntax and compatible with CommonMark. Also, DFM adds new syntax to support additional functionalities, including cross reference and file inclusion.

Note

The default markdown engine generated by docfx init has been switched to markdig engine, which is built on the top of markdig. Previous markdown engine dfm and dfm-latest will be kept for compatibiilty.

Yaml Header

Yaml header in DFM is considered as the metadata for the Markdown file. It will transform to yamlheader tag when processed.Yaml header MUST be the first thing in the file and MUST take the form of valid YAML set between triple-dashed lines. Here is a basic example:

Cross Reference

Cross reference allows you to link to another topic by using its unique identifier (called UID) instead of using its file path.

For conceptual Markdown files UID can be defined by adding a uid metadata in YAML header:

For reference topics, UIDs are auto generated from source code and can be found in generated YAML files.

You can use one of the following syntax to cross reference a topic with UID defined:

  1. Markdown link: [link_text](xref:uid_of_the_topic)
  2. Auto link: <xref:uid_of_the_topic>
  3. Shorthand form: @'uid_of_the_topic'

All will render to:

If link_text is not specified, DocFX will extract the title from the target topic and use it as the link text.

Do not use the @uid link in brackets (like this: (@uid)). DocFX cannot parse this link. The @uid link should be separated with white spaces. If you need to add a link in brackets, use [](xref:uid).

Note

Hashtag in xref is always treated as separator between file name and anchor name. That means if you have # in UID, it hasto be encoded to %23.

Actually xref format follows URI standard so all reserved characters should be encoded.

For more information, see cross reference.

File Inclusion

DFM adds syntax to include other file parts into current file, the included file will also be considered as in DFM syntax.

There are two types of file inclusion: Inline and block, as similar to inline code span and block code.

Note

YAML header is NOT supported when the file is an inclusion.

Inline

Inline file inclusion is in the following syntax, in which <title> stands for the title of the included file, and <filepath> stands for the file path of the included file. The file path can be either absolute or relative.<filepath> can be wrapped by ' or '.

Note

For inline file inclusion, the file included will be considered as containing only inline tags, for example,### header inside the file will not transfer since <h3> is a block tag, while [a](b) will transform to<a href='b'>a</a> since <a> is an inline tag.Also, ending white spaces will be trimmed, considering ending white spaces in inline inclusion in most cases are typos.

Block

Block file inclusion must be in a single line and with no prefix characters before the start [. Content inside the included file will transform using DFM syntax.

Yaml Syntax Cheat Sheet English

Section definition

User may need to define section. Mostly used for code table.Give an example below.

The above blockquote Markdown text will transform to section html as in the following:

Code Snippet

Allows you to insert code with code language specified. The content of specified code path will expand.

  • <language> can be made up of any number of character and '-'. However, the recommended value should follow Highlight.js language names and aliases.
  • <codepath> is the path relative to the file containing this markdown content in file system, which indicates the code snippet file that you want to expand.
  • <queryoption> and <queryoptionvalue> are used together to retrieve part of the code snippet file in the line range or tag name way. We have 2 query string options to represent these two ways:
query string using #query string using ?
1. line range#L{startlinenumber}-L{endlinenumber}?start={startlinenumber}&end={endlinenumber}
2. tagname#{tagname}?name={tagname}
3. multiple region rangeUnsupported?range={rangequerystring}
4. highlight linesUnsupported?highlight={rangequerystring}
5. dedentUnsupported?dedent={dedentlength}
  • In ? query string, the whole file will be included if none of the first three option is specified.
  • If dedent isn't specified, the maximum common indent will be trimmed automatically.
  • <title> can be omitted as it doesn't affect the DocFX markup result, but it can beautify the result of other Markdown engine, like GitHub Preview.

Code Snippet Sample

Tag Name Representation in Code Snippet Source File

DFM currently supports the following <language> values to be able to retrieve by tag name:

  • C family
    • Start with: // <{name}>
    • End with: // </{name}>
    • Languages:actionscript,arduino,assembly (alias: nasm),c (alias: cpp, c++, objective-c, obj-c, objc, objectivec),csharp (alias: cs),cshtml,cuda,d (alias: dlang),fsharp (alias: fs),go (alias: golang),java,javascript (alias: js, node),pascal,php,processing,rust,scala,smalltalk,swift,typescript (alias: ts)
    • File extensions:.as,.asm,.ino,.c,.cc,.cpp,.cs,.cshtml.cu,.cuh,.d,.fs,.fsi,.fsx,.go,.h,.hpp,.java,.js,.pas,.php,.pde,.rs,.scala,.st,.swift,.ts
  • Basic family
    • Start with: ' <{name}>
    • End with: ' </{name}>
    • Languages:vb,vbhtml,vbnet,vbscript
    • File extensions:.bas,.vb,.vba,.vbhtml,.vbs
  • Markup language family
    • Start with: <!-- <{name}> -->
    • End with: <!-- </{name}> -->
    • Languages:cshtml,html,vbhtml,wsdl,xml,xsl,xslt,xsd,xaml
    • File extensions:.asp,.aspx,.csdl,.cshtml,.edmx,.jsp,.vbhtml,.wsdl,.xaml,.xml,.xsd,.xsl,.xslt,.html
  • Sql family
    • Start with: -- <{name}>
    • End with: -- </{name}>
    • Languages:sql
    • File extensions:.sql
  • Script family
    • Start with: # <{name}>
    • End with: # </{name}>
    • Languages:perl,powershell (alias: posh),python,r,ruby (alias: ru),shell (alias: sh, bash)
    • File extensions:.bash,.pl,.ps1,.py,.r,.ru,.ruby,.sh
  • Special language
    • batchfile
      • Start with: rem <{name}>
      • End with: rem </{name}>
      • Languages:batchfile
      • File extensions:.bat.cmd
    • csharp
      • Start with: #region {name}
      • End with: #endregion
      • Languages:csharp (alias: cs)
      • File extensions:.cs.cshtml
    • erlang
      • Start with: % <{name}>
      • End with: % </{name}>
      • Languages:erlang
      • File extensions:.erl
    • haskell
      • Start with: -- <{name}>
      • End with: -- </{name}>
      • Languages:haskell
      • File extensions:.hs
    • matlab
      • Start with: % <{name}>
      • End with: % </{name}>
      • Languages:matlab
      • File extensions:.matlab
    • lisp
      • Start with: ; <{name}>
      • End with: ; </{name}>
      • Languages:lisp
      • File extensions:.lisp,.lsp
    • lua
      • Start with: -- <{name}>
      • End with: -- </{name}>
      • Languages:lua
      • File extensions:.lua
    • vb
      • Start with: #Region {name}
      • End with: #End Region
      • Languages:vb (alias: vbnet)
      • File extensions:.vb.vbhtml
Note

If dev-lang is not specified, file extension will be used to determine the language.

Code Snippet for Jupyter Notebooks

Allows you to insert code from a code cell of a Jupyter Notebook. The source content in the specified code cell will expand.

Steps to use this:

  1. In your Jupyter Notebook, add metadata to the code cell you will reference:

  2. In your .md file, use name to identify the cell.

Code Snippet for Jupyter Notebooks Sample

Yaml Syntax Cheat Sheet

For this Jupyter Notebook cell:

Use the markup:

to display the lines of code in the source part of the cell:

Note (Warning/Tip/Important)

Using specific syntax inside block quote to indicate the following content is Note.

The above content will be transformed to the following html:

Here are all the supported note types with the styling of the default theme applied:

Note

This is a note which needs your attention, but it's not super important.

Tip

This is a note which needs your attention, but it's not super important.

Warning

This is a warning containing some important message.

Important

This is a warning containing some important message.

Caution

This is a warning containing some important message.

Tabbed content

Syntax

  • Start a tab by a special markdown title (any level).
    • Title content should be a markdown link.
    • Link target is #tab/{tabid} or #tab/{tabid}/{condition}
  • Continue by any other content.
  • End by a markdown hr.

Example

The result will be:

Tab group 1:

Tab content-1-1.

Tab content-2-1.

Tab group 2:

Tab content-a-1.

Tab content-b-1.

Tab group 3:

Tab content-1-1.

Tab content-2-1.

Tab group 4:

Tab content-a-2.

Tab content-b-2.

Behavior

Tab groups with a same set of id are linkable in one page.

In example, tab group 1, 3 have same id set: tabid-1, tabid-2, tab group 2, 4 have same id set: tabid-a, tabid-b.

So tab group 1, 3 are linked, tab group 2, 4 are linked.When tab tabid-1 in tab group 1 is clicked, tab tabid-1 in tab group 3 will be selected in same time.But tab group 2, 4 do not have any changed.

Condition

Yaml Syntax Cheat Sheet Answers

Condition is the tab id of other table groups.

e.g.:

Yaml Syntax Cheat Sheet

Yaml Syntax Online

Result:

Tab Group 1:

Tab Group 2:

Tab content-a for 1.

Tab content-a for 2.

Tab content-b for 1.

Tab content-b for 2.

When select tabid-1 in tab group 1, you can get content-a or content-b for 1 in group 2.
When select tabid-2 in tab group 1, you can get content-a or content-b for 2 in group 2.

Video

Allows you to add videos to your topics.

Syntax:

Note

You must provide the embed uri of the video you wish to add to your topic.

Example:

Result:

Differences introduced by DFM syntax

Warning

DFM introduces more syntax to support more functionalities. When GFM does not support them, preview theMarkdown file inside GFM Preview can lead to different results.

YAML header

In GFM, YAML header must start at the very beginning of the Markdown file.In DFM, YAML header contains more powerful meanings. Refer to Yaml Header for details.

In GFM, it would be rendered as <hr>a: b<hr>.
In DFM, it would be rendered as a YAML header.

If you want to get <hr> in html in DFM, use:

or change content to make it not in YAML format:

Text after block extension

Yaml Syntax Cheat Sheet

Some block extension in DFM cannot be recognized in GFM.In GFM, it would be treated as a part of paragraph.Then, following content would be treated as a part of paragraph.

For example:

In GFM, it will be rendered as a paragraph with content [!NOTE] This is code. in blockquote.
In DFM, it will be rendered as a code in note.

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