Fix exception when using a resource with a composite primary/foreign key association

[filipegiusti]

Fixes #3334

Fix NoMethodError: undefined method to_sym' for an instance of Array` raised by this line when an association uses a composite primary key/foreign key.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

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[adrianthedev]

Thanks @filipegiusti!
Would you be able to add some tests for this as well?

The approach I would take is to create a new model & resource which uses composite foreign keys and test that.

Thank you for tackling this!

[filipegiusti]

The approach I would take is to create a new model & resource which uses composite foreign keys and test that.

I searched for a test file at spec/lib/avo/fields/belongs_to_field.rb or using the search term spec fields belongs_to but I couldn't find anything. I'm not sure where such test would be and how it would look like, I don't have much experience testing libraries.

PS: I also searched for some sort of coverage tool that would help pinpoint which tests cover that method and tried to get github copilot to find such tests, all without luck.

[adrianthedev]

Can you create a new spec next to this one and test only the composite behavior?