Duplicated values when appending to array

[crisbal]

Describe the bug

Input:

- children: ["c1"]
- children: []
- children: []
- children: ["c1", "c2"]

Query:

.[] | .children += ["a"]

Result:

children: ["c1", a, a, a, a]
children:
  - a
  - a
  - a
  - a
children:
  - a
  - a
  - a
  - a
children: ["c1", "c2", a, a, a, a]

Expected result:

- children: ["c1", "a"]
- children: ["a"]
- children: ["a"]
- children: ["c1", "c2", "a"]

Version of yq: 4.22.1
Operating system: linux
Installed via: binary

---

jq behaviour

yq -o json /tmp/bug.yml | jq '.[] | .children += ["a"]'
{
  "children": [
    "c1",
    "a"
  ]
}
{
  "children": [
    "a"
  ]
}
{
  "children": [
    "a"
  ]
}
{
  "children": [
    "c1",
    "c2",
    "a"
  ]
}

[crisbal]

The following works instead.

>>> yq '.[].children += ["a"]' /tmp/bug.yml
- children: ["c1", a]
- children:
    - a
- children:
    - a
- children: ["c1", "c2", a]

[crisbal]

More interesting use case

Input:

- type: "skip"
  children: ["c1"]
- type: "skip"
  children: []
- type: "ok"
  children: []
- type: "ok"
  children: ["c1", "c2"]

Query:

yq 'map(select(.type != "skip").children += ["a"])' /tmp/bug.yml

Output:

- type: "skip"
  children: ["c1"]
- type: "skip"
  children: []
- type: "ok"
  children:
    - a
    - a
    - a
    - a
- type: "ok"
  children: ["c1", "c2", a, a, a, a]

[mikefarah]

Thanks for raising with a clear example, definitely a bug, looking in to it.

[mikefarah]

Fixed in 4.23.1

[crisbal]

Thanks for the quick fix! Really appreciate it. I will give it a try on monday.