Delete an item if another item in the same document meets a condition

[tukusejssirs]

I have multiple documents that need to be processed at the same time, for example:

metadata:
  name: apple
spec
  allow:
    logins:
      - one
      - two
      - four
---
metadata:
  name: pear
spec
  allow:
    logins:
      - three
      - four

Now, I need to remove four from .spec.allow.logins, but only if .metadata.name is pear.

Expected output:

metadata:
  name: apple
spec
  allow:
    logins:
      - one
      - two
      - four
---
metadata:
  name: pear
spec
  allow:
    logins:
      - three

To remove four from all documents, I can use yq 'del(.spec.allow.logins[] | select(. == "pear")), but how can I define another condition? Do I need to use alias (. as $root) to be able reference a different path from .spec.allow.logins[]? And how to construct two mandatory conditions (c1 && c2)?

Thanks in advance! 🙏

[mikefarah]

Hi!

Here's the expression you need to run:

yq 'del(select(.metadata.name == "pear") | .spec.allow.logins[] | select(. == "four"))' file.yaml

It's very similar to what you had, but it first has select(.metadata.name == "pear") to select only the documents that have metadata.name == "pear" :)

To do two conditions, you can use "and", so for instance: select(.metadata.name == "pear" and .some.thing == "dog")

[tukusejssirs]

Thanks! It works flawlessly! 🙏

To do two conditions, you can use "and", so for instance: select(.metadata.name == "pear" and .some.thing == "dog")

Well, at first I tought that I cannot go back to the root in del() after first select() (I thought this because of select(. == "four") where . means .spec.allow.logins[] which I still have no idea why it is so, but nevermind). However, and seems not to be documented (but or is), so I assumed and exists too, but I could not solve the problem in the OP with it.

Maybe you could add all these examples from GitHub Discussions to the docs, at least as special use cases or whatever. I personally find them more useful in complex cases than the simple examples in the docs, because sometimes (like in this case) I have trouble to join multiple operations into one expression. 🙏