YAML - Indentation and Separation

Indentation and separation are two main concepts when you are learning any programming language. This chapter talks about these two concepts related to YAML in detail.

Indentation of YAML

YAML does not include any mandatory spaces. Further, there is no need to be consistent. The valid YAML indentation is shown below −

a:
   b:
      - c
      -  d
      - e
f:
      "ghi"

  • You should remember the following rules while working with indentation in YAML:Flow blocks must be intended with at least some spaces with surrounding current block level.

  • Flow content of YAML spans multiple lines. The beginning of flow content begins with { or [.

  • Block list items include same indentation as the surrounding block level because - is considered as a part of indentation.

Example of Intended Block

Observe the following code that shows indentation with examples −

--- !clarkevans.com/^invoice
invoice: 34843
date   : 2001-01-23
bill-to: &id001
   given  : Chris
   family : Dumars
   address:
      lines: |
            458 Walkman Dr.
            Suite #292
      city    : Royal Oak
      state   : MI
      postal  : 48046
ship-to: *id001
product:
    - sku         : BL394D
      quantity    : 4
      description : Basketball
      price       : 450.00
   - sku         : BL4438H
      quantity    : 1
      description : Super Hoop
      price       : 2392.00
tax  : 251.42
total: 4443.52
comments: >
    Late afternoon is best.
    Backup contact is Nancy
    Billsmer @ 338-4338.

Separation of Strings

Strings are separated using double-quoted string. If you escape the newline characters in a given string, it is completely removed and translated into space value.

Example

In this example we have focused listing of animals listed as an array structure with data type of string. Every new element is listed with a prefix of hyphen as mentioned as prefix.

-
 - Cat
 - Dog
 - Goldfish
-
 - Python
 - Lion
 - Tiger

Another example to explain string representation in YAML is mentioned below.

 errors:
      messages:
         already_confirmed: "was already confirmed, please try signing in"
         confirmation_period_expired: "needs to be confirmed within %{period}, please request a new one"
         expired: "has expired, please request a new one"
         not_found: "not found"
         not_locked: "was not locked"
         not_saved:
            one: "1 error prohibited this %{resource} from being saved:"
            other: "%{count} errors prohibited this %{resource} from being saved:"

This example refers to the set of error messages which a user can use just by mentioning the key aspect and to fetch the values accordingly. This pattern of YAML follows the structure of JSON which can be understood by user who is new to YAML.

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