yq/pkg/yqlib/doc/usage/recipes.md

Find items in an array

Given a sample.yml file of:

- name: Foo
  numBuckets: 0
- name: Bar
  numBuckets: 0

then

yq '.[] | select(.name == "Foo")' sample.yml

will output

name: Foo
numBuckets: 0

Explanation:

• .[] splats the array, and puts all the items in the context.
• These items are then piped (|) into select(.name == "Foo") which will select all the nodes that have a name property set to 'Foo'.
• See the select operator for more information.

Find and update items in an array

Given a sample.yml file of:

- name: Foo
  numBuckets: 0
- name: Bar
  numBuckets: 0

then

yq '(.[] | select(.name == "Foo") | .numBuckets) |= . + 1' sample.yml

will output

- name: Foo
  numBuckets: 1
- name: Bar
  numBuckets: 0

Explanation:

• Following from the example above.[] splats the array, selects filters the items.
• We then pipe (|) that into .numBuckets, which will select that field from all the matching items
• Splat, select and the field are all in brackets, that whole expression is passed to the |= operator as the left hand side expression, with . + 1 as the right hand side expression.
• |= is the operator that updates fields relative to their own value, which is referenced as dot (.).
• The expression . + 1 increments the numBuckets counter.
• See the assign and add operators for more information.