Advanced Features in YAML¶

Now that we're familiar with the basics of YAML, let's explore some advanced features like multiline strings, anchors and aliases, etc.

Multiline String in YAML¶

In YAML, you can create a multiline string using the pipe character | or the greater than symbol >.

Multiline String Using Greater Than Symbol¶

You can use > if you want the line breaks to be stripped out. You'll still have one line break at the end. You can use >- if you want to strip the line break at the end as well.

1. Multiline string using >:

   # Using the greater than symbol
   multiline_string: >
     This is a 
     multiline 
     string 
     in YAML.
   

   YAML will treat the string as:

   This is a multiline string in YAML.\n
   

2. Multiline string using >-:

   # Using the greater than symbol
   multiline_string: >-
     This is a 
     multiline 
     string 
     in YAML.
   

   YAML will treat the string as:

   This is a multiline string in YAML.
   

Multiline String Using Pipe Character¶

You can use | if you want the line breaks to be preserved as \n. You can use |- if you want to strip the line break at the end.

1. Multiline string using |:

   # Using the pipe character
   multiline_string: |
     This is a 
     multiline 
     string 
     in YAML.
   

   YAML will treat the string as:

   This is a 
   multiline 
   string 
   in YAML.\n
   

2. Multiline string using |-:

   # Using the pipe character
   multiline_string: |
     This is a 
     multiline 
     string 
     in YAML.
   

   YAML will treat the string as:

   This is a 
   multiline 
   string 
   in YAML.
   

Anchors and Aliases in YAML¶

YAML allows you to use anchors and aliases to create references to other parts of the document. This can be useful for avoiding repetition and simplifying complex structures.

Anchor¶

An anchor is a name assigned to a specific value in the YAML document. It's indicated using the & character followed by the anchor name. For example:

# Define an anchor for a list of values
list: &my_list
  - apple
  - banana
  - mango

In this example, the anchor name is my_list and it refers to the list of values ["apple", "banana", "mango"].

Alias¶

An alias is a reference to an anchor in the YAML document. It's indicated using the * character followed by the anchor name. For example:

# Use an alias to reference the list of values
fruits: *my_list

In this example, the fruits list contains an alias to the my_list anchor. When this YAML document is parsed, the alias will be replaced with the corresponding anchor value, resulting in the following list:

fruits:
  - apple
  - banana
  - orange

Using Anchor and Alias¶

Here's an example document that uses anchor and alias:

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list: &my_list
  - apple
  - banana
  - mango

fruits: *my_list

The above YAML is equivalent to the following YAML document:

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list:
  - apple
  - banana
  - mango

fruits:
  - apple
  - banana
  - mango