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.

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

To merge only existing fields, use the *? form. Note that this can be used with the concatenate arrays too *+?. Note that when merging objects, this operator returns the merged object (not the parent). This will be clearer in the examples below.

Multiplication of strings and numbers are not yet supported.

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

then

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

will output

field:
  g: wizz
fieldA: cat
fieldB: dog

Merge objects together, returning parent object

Given a sample.yml file of:

a:
  field: me
  fieldA: cat
b:
  field:
    g: wizz
  fieldB: dog

then

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

will output

a:
  field:
    g: wizz
  fieldA: cat
  fieldB: dog
b:
  field:
    g: wizz
  fieldB: dog

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

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

Merge arrays

Given a sample.yml file of:

a:
  - 1
  - 2
  - 3
b:
  - 3
  - 4
  - 5

then

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

will output

a:
  - 3
  - 4
  - 5
b:
  - 3
  - 4
  - 5

Merge, only existing fields

Given a sample.yml file of:

a:
  thing: one
  cat: frog
b:
  missing: two
  thing: two

then

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

will output

thing: two
cat: frog

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

then

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

will output

array:
  - 1
  - 2
  - animal: dog
  - 3
  - 4
  - animal: cat
value: banana

Merge, only existing fields, appending arrays

Given a sample.yml file of:

a:
  thing:
    - 1
    - 2
b:
  thing:
    - 3
    - 4
  another:
    - 1

then

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

will output

thing:
  - 1
  - 2
  - 3
  - 4

Merge to prefix an element

Given a sample.yml file of:

a: cat
b: dog

then

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

will output

a:
  c: cat
b: dog

Merge with simple aliases

Given a sample.yml file of:

a: &cat
  c: frog
b:
  f: *cat
c:
  g: thongs

then

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

will output

g: thongs
f: *cat

Merge copies anchor names

Given a sample.yml file of:

a:
  c: &cat frog
b:
  f: *cat
c:
  g: thongs

then

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

will output

g: thongs
c: &cat frog

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

then

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

will output

c: foobarList_c
<<:
  - *foo
  - *bar
thing: foobar_thing
b: foobarList_b