day17.md

On the seventeenth day, I learned the following things about YAML.

Write a sequence

---
student: !!seq
- mark
- name
- roll_no
...

Empty sequence will be called sparse sequence

---
sparse seq:
- how
- where
- 
- Null
- sup
...

Write a nested sequence

---
-
- mango
- orange
- apple
- 
- car
- truck
- bus
...

Key value pairs are called maps

!!map

Write nested mappings: map within a map

---
name: Bilal Khan
roles:
age: 12
job: software engineer
...

same like this

---
name: Bilal Khan
roles: {age: 12, job: software engineer}
...

Write pairs which means that one key may have multiple values

!!pairs

Example

---
pair example: !!pairs
- job: student
- job: teacher
...

same like this

---
pair example: !!pairs [job: student, job: teacher]
...

this will be an array of hashtables

Set will allow you to have unique values

---
names: !!set
? Bilal
? Ali
? Ahmed
...

Write a dictionary that will represent sequence as a value

!!omap

Example

---
people:
- Bilal:
    name: Bilal Khan
    age: 25
    role: software engineer
- Ali:
    name: Ali Ahmed
    age: 19
    role: data scientist
...

Re-use some properties using anchors

likings: &fruitsChoice
like: mango
dislike: banana

person1:
name: Bilal
<<: *fruitsChoice

person2:
name: Hamza
<<: *fruitsChoice

person3:
name: Ali
<<: *fruitsChoice

Result

person1:
name: Bilal
like: mango
dislike: banana

If you want to override some data. The data will be replaced with a new one

person1:
name: Bilal
like: mango
<<: *fruitsChoice
dislike: orange

Result

person1:
name: Bilal
like: mango
dislike: orange

Example of multiple nested sequence

Schools:
- name: DPS
    principal: Someone
    students:
    - roll_no: 12
        name: Bilal Khan
        marks: 5

Explaining it in a video

Here you can get an explanation in a video. 17/60 Day of DevOps Challenge