App: Allow interpolation string as the only value on input-code interface

[joselcvarela]

Scope

When using Flows, there's cases that we just want to pass the response from previous operation to the next one.
For example, we might want to pass the payload of a Read Date operation to another flow using Trigger Flow operation.
For such cases we should be able to pass the following into the Payload option of Trigger Flow operation:

{{ $last }}

Although, the Code interface will complain because the Payload option is defined as JSON and this value is not a valid JSON so the linter will show an error.
Since this is a valid action to do (to pass {{ $last }}), in this PR we ignore the lint if the value is an interpolation, i.e., if the value starts with {{ and ends with }}.

What's changed:

• Allow interpolation at root level of Code interface using JSON language

Potential Risks / Drawbacks

• If the value used is not an interpolation but anything that starts with {{ and ends with }}, there will be no errors

Review Notes / Questions

• This seems to be a nice first approach to this. Although we should also be able to validate the payload on the API. I have not did it since I didn't found any example on how to validate requests according to the entity.
  For example, we could try add some validation into OperationsService but the App send the operation data within a flow which will be handled by FlowService so no validation would be made

Comparision

Before	After
Screen.Recording.2024-04-25.at.19.07.03.mov	Screen.Recording.2024-04-25.at.19.06.03.mov
In this case you can see that when using {{$last}} the Code interface shows an error. Although the Flow works as expected. When I type "{{ $last }}" the Flow throws an error.	In this case you can see that using {{$last}} does not show any error any more and Flow works as expected. Although when typing "{{ $last }}" it will still throw an error as " are not removed and Flow will have double quotes conflicting.

---

Fixes #21263

[changeset-bot]

🦋 Changeset detected

Latest commit: 915abeb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@directus/app	Patch
@directus/api	Patch
directus	Patch

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[paescuj]

Since this is only applicable in context of Flows, we should add an option to the interface that allows us to control this behavior.

[paescuj]

@joselcvarela Had another idea: How about auto switching to raw editor if a plain interpolation string is detected? Then we wouldn't have to touch the input-code interface and it might make it a bit clearer for the user.

[paescuj]

Works as intended 🚀

(On my previous idea: Would be a bigger changeover as the code interface currently only emits when value is valid... Not worth it at the moment.)