Traverse (Read)
This is the simplest (and perhaps most used) operator. It is used to navigate deeply into yaml structures.
NOTE --yaml-fix-merge-anchor-to-spec flag
yq
doesn't merge anchors <<:
to spec, in some circumstances it incorrectly overrides existing keys when the spec documents not to do that.
To minimise disruption while still fixing the issue, a flag has been added to toggle this behaviour. This will first default to false; and log warnings to users. Then it will default to true (and still allow users to specify false if needed)
See examples of the flag differences below, where LEGACY is the flag off; and FIXED is with the flag on.
Simple map navigation
Given a sample.yml file of:
a:
b: apple
then
yq '.a' sample.yml
will output
b: apple
Splat
Often used to pipe children into other operators
Given a sample.yml file of:
- b: apple
- c: banana
then
yq '.[]' sample.yml
will output
b: apple
c: banana
Optional Splat
Just like splat, but won't error if you run it against scalars
Given a sample.yml file of:
cat
then
yq '.[]' sample.yml
will output
Special characters
Use quotes with square brackets around path elements with special characters
Given a sample.yml file of:
"{}": frog
then
yq '.["{}"]' sample.yml
will output
frog
Nested special characters
Given a sample.yml file of:
a:
"key.withdots":
"another.key": apple
then
yq '.a["key.withdots"]["another.key"]' sample.yml
will output
apple
Keys with spaces
Use quotes with square brackets around path elements with special characters
Given a sample.yml file of:
"red rabbit": frog
then
yq '.["red rabbit"]' sample.yml
will output
frog
Dynamic keys
Expressions within [] can be used to dynamically lookup / calculate keys
Given a sample.yml file of:
b: apple
apple: crispy yum
banana: soft yum
then
yq '.[.b]' sample.yml
will output
crispy yum
Children don't exist
Nodes are added dynamically while traversing
Given a sample.yml file of:
c: banana
then
yq '.a.b' sample.yml
will output
null
Optional identifier
Like jq, does not output an error when the yaml is not an array or object as expected
Given a sample.yml file of:
- 1
- 2
- 3
then
yq '.a?' sample.yml
will output
Wildcard matching
Given a sample.yml file of:
a:
cat: apple
mad: things
then
yq '.a."*a*"' sample.yml
will output
apple
things
Aliases
Given a sample.yml file of:
a: &cat
c: frog
b: *cat
then
yq '.b' sample.yml
will output
*cat
Traversing aliases with splat
Given a sample.yml file of:
a: &cat
c: frog
b: *cat
then
yq '.b[]' sample.yml
will output
frog
Traversing aliases explicitly
Given a sample.yml file of:
a: &cat
c: frog
b: *cat
then
yq '.b.c' sample.yml
will output
frog
Traversing arrays by index
Given a sample.yml file of:
- 1
- 2
- 3
then
yq '.[0]' sample.yml
will output
1
Traversing nested arrays by index
Given a sample.yml file of:
[[], [cat]]
then
yq '.[1][0]' sample.yml
will output
cat
Maps with numeric keys
Given a sample.yml file of:
2: cat
then
yq '.[2]' sample.yml
will output
cat
Maps with non existing numeric keys
Given a sample.yml file of:
a: b
then
yq '.[0]' sample.yml
will output
null
Traversing 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 '.foobar.a' sample.yml
will output
foo_a
Traversing merge anchors with local override
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 '.foobar.thing' sample.yml
will output
foobar_thing
Select multiple indices
Given a sample.yml file of:
a:
- a
- b
- c
then
yq '.a[0, 2]' sample.yml
will output
a
c
LEGACY: Traversing merge anchors with override
This is legacy behaviour, see --yaml-fix-merge-anchor-to-spec
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 '.foobar.c' sample.yml
will output
foo_c
LEGACY: Traversing merge anchor lists
Note that the later merge anchors override previous, but this is legacy behaviour, see --yaml-fix-merge-anchor-to-spec
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 '.foobarList.thing' sample.yml
will output
bar_thing
LEGACY: Splatting merge anchors
With legacy override behaviour, see --yaml-fix-merge-anchor-to-spec
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 '.foobar[]' sample.yml
will output
foo_c
foo_a
foobar_thing
LEGACY: Splatting merge anchor lists
With legacy override behaviour, see --yaml-fix-merge-anchor-to-spec
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 '.foobarList[]' sample.yml
will output
bar_b
foo_a
bar_thing
foobarList_c
FIXED: Traversing merge anchors with override
Set --yaml-fix-merge-anchor-to-spec=true
to get this correct merge behaviour.
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 '.foobar.c' sample.yml
will output
foobar_c
FIXED: Traversing merge anchor lists
Set --yaml-fix-merge-anchor-to-spec=true
to get this correct merge behaviour. Note that the keys earlier in the merge anchors sequence override later ones
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 '.foobarList.thing' sample.yml
will output
foo_thing
FIXED: Splatting merge anchors
Set --yaml-fix-merge-anchor-to-spec=true
to get this correct merge behaviour. Note that the keys earlier in the merge anchors sequence override later ones
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 '.foobar[]' sample.yml
will output
foo_a
foobar_thing
foobar_c
FIXED: Splatting merge anchor lists
Set --yaml-fix-merge-anchor-to-spec=true
to get this correct merge behaviour. Note that the keys earlier in the merge anchors sequence override later ones
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 '.foobarList[]' sample.yml
will output
foobarList_b
foo_thing
foobarList_c
foo_a
Last updated
Was this helpful?