Add to non-existing array

[saadlu]

Given a yaml

spec:
   some: wombat

in V3, the following worked

yq w -i file.yaml 'spec.config[+]' a

giving

spec:
  some: wombat
  config:
    - a 

Subsequently we can add more elements to the array by running the same yq command.

What's the corresponding command in V4?

Doing

yq e -i '.spec.config + "a"' file.yaml

gives

Error: !!null cannot be added to !!str

could do

yq e -i '.spec.config[0] = a' file.yaml

but this requires maintaing the index, no?

[mikefarah]

I'd use the alternative operator with add:

yq e -i '.spec.config = .spec.config // [] + "a"' file.yaml

[saadlu]

cool thanks :)

[saadlu]

@mikefarah Just discovered that this, although worked in 4.4.0, does not work in 4.5.0, 4.6.0 ..

[saadlu]

ah its precedence

to make it work in 4.5.0+ need to do

yq e -i '.spec.config = (.spec.config // []) + "a"' file.yaml

[mudideng]

How does the formatting work on this @mikefarah?
If I create an empty array first yq e -i '.spec.config = []' file.yaml, it seems like it will always stick to the format
[a, b, c] instead of

- a
- b
- c

when I later do yq e -i '.spec.config += "a"' file.yaml. Is there a way to force the format to the latter?