What is YAML?

• YAML is a data serialization language for storing information in a human-readable form.

• YAML stands for "YAML Ain't Markup Language."

• YAML is not a Markup Language.

• YAML is used to store complex data in a compact and readable format.

• YAML was originally designed as a configuration language but is now used in various applications.

• We can use YAML to define key and value pairs like variables, lists and objects

• YAML is very similar to JSON (Javascript Object Notation) and XML (Extensible Markup Language)

• YAML primarily focuses on readability and user-friendliness.

• YAML is designed to be clean and easy to read.

• We can define YAML files with two different extensions.

• .yml

• .yaml

YAML BASICS

• YAML Comments

• YAML Key-Value Pairs

• YAML Dictionary or Map

• YAML Array / Lists

• YAML Pipe

• YAML Greater than Sign

• YAML Document Separator

YAML Comments

• We can have comments in YAML with a # sign. Below is an example.

#YAML Tutorial
#Written by Ram

YAML – Key-Value Pairs

• YAML documents will be full of key-value pairs.

• Key and Value are separated by a colon.

• We must have a space after the colon differentiating the value.

• YAML Supports different data types.

• Integer

• Floating point Numbers

• Strings

• Boolean

• Dates - Format: ISO 8601

• Null values

• Important Note for Strings: Quote strings when they have special characters like colons :, braces {}, pipes |, brackets []

#Key Value Pairs
Name: Ram
Age: 22
Gpa: 9.0
Occupation: DevOps Engineer
State: 'Andhra Pradesh [AP]'
AboutMe: "I am a DevOps engineer"
Male: true
DateOfBith: 2001-11-26T15:53:00
PoliceCases: null

Strings are a collection of characters that represent a sentence or phrase. You either use | to print each string as a new line or > to print it as a paragraph.

Strings in YAML do not need to be in double quotes.

#DatatTypes Examples
integer: 25
hex: 0x12d4 #evaluates to 4820
octal: 023332 #evaluates to 9946

float: 25.0
exponent: 12.3015e+05 #evaluates to 1230150.0

boolean: Yes
string: "25"

infinity: .inf # evaluates to infinity
neginf: -.Inf #evaluates to negative infinity
not: .NAN #Not a Number

YAML Array / Lists

• YAML List is indented with an opening dash.

• Dash indicates that it’s an element of an array.

• All members of a list are lines beginning at the same indentation level starting with a ”-” (a dash and a space)

• Block Sequence indicates each entry with a dash and space

• Flow Sequence is written as a comma-separated list within square brackets

#Block Sequence
Persons:
  - Ram
  - Bhadra
  - Sravan
  - Ravi
#Flow Sequence
Persons: [Ram, Bhadra, Sravan, Ravi]

YAML Dictionary or Map

• Dictionaries are collections of key-value pairs all nested under the same subgroup. They help to divide data into logical categories for later use.

• Dictionaries are defined like mappings in that you enter the dictionary name, a colon, and a space followed by one or more indented key-value pairs.

person:
  name: Ram
  age: 22
  city: kadapa

YAML lists containing dictionaries containing lists

Persons:
  - Ram:
      Age: 22
      Occupation: DevOps Engineer
      State: London
      Degrees:
        - Bachelors
        - Masters
  - Ravi:
      Age: 22
      Occupation: Developer
      State: California
      Degrees: [Bachelors, Masters] # List with a differnt notation
  - Sravan:
      Age: 23
      Occupation: Cloud Developer
      State: Texas
      Degrees:
       - Masters

YAML Pipe

• The pipe notation is also referred to as a literal block.

• All new lines, indentation, extra spaces everything preserved as is.

str: Hello World
data: |
   These
   Newlines
   Are broken up

YAML Greater than Sign

• The greater-than-sign notation is also referred to as a folded block.

• Renders the text as a single line.

• All new lines will be replaced with a single space.

• Blank lines are converted to newline characters.

str: Hello World
data: >
   This text is
   wrapped and is a
   single paragraph

YAML Document Separator

• You can have multiple YAML documents in a single YAML file to make file organization or data parsing easier.

• The separation between each document is marked by three dashes (---)

---
person: Ram
Hobbies: cooking
---
player: Ravi
action: cycling
---

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