yq/pkg/yqlib/doc/Update Assign Operator.md

Updates the LHS using the expression on the RHS. Note that the RHS runs against the original LHS value, so that you can evaluate a new value based on the old (e.g. increment).

Examples

Update parent to be the child value

Given a sample.yml file of:

a:
  b:
    g: foof

then

yq eval '.a |= .b' sample.yml

will output

{a: {g: foof}}

Update string value

Given a sample.yml file of:

a:
  b: apple

then

yq eval '.a.b |= "frog"' sample.yml

will output

{a: {b: frog}}

Update selected results

Given a sample.yml file of:

a:
  b: apple
  c: cactus

then

yq eval '.a[] | select(. == "apple") |= "frog"' sample.yml

will output

{a: {b: frog, c: cactus}}

Update array values

Given a sample.yml file of:

- candy
- apple
- sandy

then

yq eval '.[] | select(. == "*andy") |= "bogs"' sample.yml

will output

[bogs, apple, bogs]

Update empty object

Given a sample.yml file of:

'': null

then

yq eval '.a.b |= "bogs"' sample.yml

will output

{a: {b: bogs}}

Update empty object and array

Given a sample.yml file of:

'': null

then

yq eval '.a.b[0] |= "bogs"' sample.yml

will output

{a: {b: [bogs]}}