yq/pkg/yqlib/doc/operators/create-collect-into-object.md

Create, Collect into Object

This is used to construct objects (or maps). This can be used against existing yaml, or to create fresh yaml documents.

{% hint style="warning" %} Note that versions prior to 4.18 require the 'eval/e' command to be specified.

yq e <exp> <file> {% endhint %}

Collect empty object

Running

yq --null-input '{}'

will output

{}

Wrap (prefix) existing object

Given a sample.yml file of:

name: Mike

then

yq '{"wrap": .}' sample.yml

will output

wrap:
  name: Mike

Using splat to create multiple objects

Given a sample.yml file of:

name: Mike
pets:
  - cat
  - dog

then

yq '{.name: .pets.[]}' sample.yml

will output

Mike: cat
Mike: dog

Working with multiple documents

Given a sample.yml file of:

name: Mike
pets:
  - cat
  - dog
---
name: Rosey
pets:
  - monkey
  - sheep

then

yq '{.name: .pets.[]}' sample.yml

will output

Mike: cat
Mike: dog
Rosey: monkey
Rosey: sheep

Creating yaml from scratch

Running

yq --null-input '{"wrap": "frog"}'

will output

wrap: frog

Creating yaml from scratch with multiple objects

Running

yq --null-input '(.a.b = "foo") | (.d.e = "bar")'

will output

a:
  b: foo
d:
  e: bar