yq/pkg/yqlib/doc/Multiply.md

Like the multiple operator in jq, depending on the operands, this multiply operator will do different things. Currently only objects are supported, which have the effect of merging the RHS into the LHS.

Upcoming versions of yq will add support for other types of multiplication (numbers, strings).

To concatenate when merging objects, use the *+ form (see examples below). This will recursively merge objects, appending arrays when it encounters them.

Note that when merging objects, this operator returns the merged object (not the parent). This will be clearer in the examples below.

Merging files

Note the use of eval-all to ensure all documents are loaded into memory.

yq eval-all 'select(fileIndex == 0) * select(fileIndex == 1)' file1.yaml file2.yaml

Merge objects together, returning merged result only

Given a sample.yml file of:

a: {field: me, fieldA: cat}
b: {field: {g: wizz}, fieldB: dog}
'': null

then

yq eval '.a * .b' sample.yml

will output

{'': null}

Merge objects together, returning parent object

Given a sample.yml file of:

a: {field: me, fieldA: cat}
b: {field: {g: wizz}, fieldB: dog}
'': null

then

yq eval '. * {"a":.b}' sample.yml

will output

'': null

Merge keeps style of LHS

Given a sample.yml file of:

a: {things: great}
b:
  also: "me"

then

yq eval '. * {"a":.b}' sample.yml

will output

'': null

Merge arrays

Given a sample.yml file of:

a: [1, 2, 3]
b: [3, 4, 5]
'': null

then

yq eval '. * {"a":.b}' sample.yml

will output

'': null

Merge, appending arrays

Given a sample.yml file of:

a: {array: [1, 2, {animal: dog}], value: coconut}
b: {array: [3, 4, {animal: cat}], value: banana}
'': null

then

yq eval '.a *+ .b' sample.yml

will output

{'': null}

Merge to prefix an element

Given a sample.yml file of:

a: cat
b: dog
'': null

then

yq eval '. * {"a": {"c": .a}}' sample.yml

will output

'': null

Merge with simple aliases

Given a sample.yml file of:

a: &cat {c: frog}
b: {f: *cat}
c: {g: thongs}
'': null

then

yq eval '.c * .b' sample.yml

will output

{'': null}

Merge does not copy anchor names

Given a sample.yml file of:

a: {c: &cat frog}
b: {f: *cat}
c: {g: thongs}
'': null

then

yq eval '.c * .a' sample.yml

will output

{'': null}

Merge with merge anchors

Given a sample.yml file of:

foo: &foo
  a: foo_a
  thing: foo_thing
  c: foo_c
bar: &bar
  b: bar_b
  thing: bar_thing
  c: bar_c
foobarList:
  b: foobarList_b
  !!merge <<: [*foo, *bar]
  c: foobarList_c
foobar:
  c: foobar_c
  !!merge <<: *foo
  thing: foobar_thing
'': null

then

yq eval '.foobar * .foobarList' sample.yml

will output

'': null