[pkg/ottl] Add contains function

[lkwronski]

Description: Adds a new contains function to check if slice contains item.

Link to tracking Issue: Fixes #30420

Testing: Added unit test

Documentation: TODO

[michalpristas]

this won't allow you to pass a slice, consider this use case
contains(attributes["tags"], "staging")

[lkwronski]

Maybe I'm wrong, but I tried to write e2e test and it seems that the following statement works and I can pass the slices:

set(attributes["test"], "pass") where Contains(["hello", "world"], "hello")

Did I miss anything?

[michalpristas]

the thing is you're just assuming StringLikeGetter,
when I want to use config like this

 - context: log
        statements: 
          - set(attributes["tags"], ["staging", "hello", "world", "work"])
          - set(attributes["staging"], "true") where Contains(attributes["tags"], "staging")

Contains fail because first attribute is not an array.
so i need to fix it like this

    log_statements:
      - context: log
        statements: 
          - set(attributes["tags"], ["staging", "hello", "world", "work"])
          - set(attributes["staging"], "true") where Contains([attributes["tags"]], "staging")

by wrapping attributes["tags"] with [] to make it an array.
when i do that, your StringLikeGetter will get the attributes["tags"] and finds out it's a Slice. So it makes a string out of slice by marshaling the array.
Now you have marshaled array as a string["staging", "hello", "world", "work"] that does not equal staging in my condition.

What you need to do is to use Getter and work with different types you may get. You may get Slice, Map or a string wrapped in pcommon.Value. You should handle all of these differently.

While you're at it changing behavior to match what i described i would be the same way to add support for ints, floats and boolean as you were asking in the other comment

It will also fix UX.
I want to use Contains(["a", "b"...] and Contains(attributes["tags"] at the same time without wrapping workaround

[lkwronski]

I really appreciate the detailed answer that helps me understand the flow. Thanks.

I added e2e with the scenario you described. I hope it is better now.

[michalpristas]

not sure i like that, especially when we have so few types we support

[lkwronski]

You're right, I removed the reflection and it simplified things a bit.

[evan-bradley]

Suggested change

	note: Add typed getter for `pcommon.Slice`
	note: Add `PSliceGetter`, a typed getter for `pcommon.Slice`

[evan-bradley]

Suggested change

	change_logs: [user]
	change_logs: [api]

[evan-bradley]

Suggested change

	return pcommon.Map{}, TypeError(fmt.Sprintf("expected pcommon.Map but got %T", v))
	return pcommon.Map{}, TypeError(fmt.Sprintf("expected pcommon.Map but got %v", v.Type()))

Sorry, I got this wrong before. Since this is a pdata object, we should use its Type method.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.