Syntax and Structure 🧩¶

YAML (YAML Ain't Markup Language) is designed to be a human-readable data serialization format. Its syntax and structure are simple, making it easy to write and read.

Indentation and Whitespace 📏¶

Spaces Only: YAML uses spaces for indentation, not tabs. Consistent indentation is crucial.

Levels of Indentation: Indentation levels define the hierarchy and structure of the document.

yml
key1: value1
key2:
  nestedKey1: nestedValue1
  nestedKey2: nestedValue2

key2 contains a nested mapping, which is indented.

Comments 💬¶

Single-Line Comments: Start with #. Used to add notes or explanations.

yml
# This is a comment
name: chaitu-ycr  # Inline comment

Scalars 📜¶

Basic Values: Strings, numbers, booleans, and nulls.
Strings
- Plain: name: chaitu-ycr
- Single-quoted: name: 'chaitu-ycr'
- Double-quoted: name: "chaitu-ycr"
- Multiline
  - Block Scalar (|): Preserves line breaks.
  - Folded Scalar (>): Folds line breaks into spaces.
- In YAML, >+, >-, |+, and |- are used to control the formatting and handling of multiline strings, which are known as block scalars.

yml
block: |
  This is a literal scalar.
  Line breaks will be preserved.
  Exactly as written.

block_keep: |+
  This is a literal scalar.
  Line breaks will be preserved.
  Exactly as written.

block_strip: |-
  This is a literal scalar.
  Line breaks will be preserved.
  Exactly as written.

folded: >
  This is a folded scalar.
  New lines will be folded into spaces
  when rendered.

folded_keep: >+
  This is a folded scalar.
  New lines will be folded into spaces.

folded_strip: >-
  This is a folded scalar.
  New lines will be folded into spaces.

Lists (Sequences) 📋¶

Dash and Space: Use - followed by a space for each item.

yml
fruits:
  - 🍎 Apple
  - 🍌 Banana
  - 🍒 Cherry

Nested Lists: Lists can contain other lists or mappings.

yml
favorites:
  - colors:
      - 🔴 Red
      - 🟢 Green
      - 🔵 Blue
  - numbers:
      - 1️⃣ One
      - 2️⃣ Two
      - 3️⃣ Three

Mappings (Dictionaries) 📑¶

Key-Value Pairs: Separate keys and values with a colon and space.

yml
person:
  name: chaitu-ycr
  age: 30
  city: chennai 🏙️

Nested Mappings: Mappings can contain other mappings.

yml
company:
  name: ycr TechCorp
  location:
    city: chennai 🏙️
    state: Tamil Nadu 🛕

Inline Collections 📖¶

Inline Lists and Mappings: Use square brackets for lists and curly braces for mappings.

yml
inline_list: [🍎 Apple, 🍌 Banana, 🍒 Cherry]
inline_mapping: {name: chaitu-ycr, age: 30, city: chennai 🏙️}

Anchors and Aliases 🔗¶

Reuse Values: Use anchors (&) to define reusable content and aliases (*) to reference it.

yml
defaults: &defaults
  country: INDIA in
  currency: RUPEE 💵

location1:
  <<: *defaults
  city: chennai 🏙️

location2:
  <<: *defaults
    city: Pondicherry 🌴

defaults anchor is reused in location1 and location2 with <<: *defaults.

Complex Keys 🧩¶

Use Complex Types: Sequences or mappings can be used as keys by enclosing them in ? and :.

yml
? [first, second]
: "Tuple as a key"

Multi-Document Files 📂¶

Separate Documents: Use --- to separate multiple documents within a single YAML file.

yml
---
document1:
  key1: value1
---
document2:
  key2: value2