Updated checkPromptType function to handle prompt list in completions

[AyushSawant18588]

Describe the change
The checkPromptType function has been updated to support validation of []interface{} slices, ensuring that each element in the slice is of type string.
Currently if list of string is provided in prompt field ErrCompletionRequestPromptTypeNotSupported error is returned.
Example:
for this completions request-

{
	"model": "gemma-vllm",
	"prompt": ["Explain transformers in atelast 100 words or more","Hello whoare you"],
	"max_tokens": 150
}

This error will occur-

Completion error: the type of CompletionRequest.Prompt only supports string and []string

This is because arrays in JSON are decoded into Go as slices of interface{} ([]interface{}), not as slices of a specific type like []string. Therefore, when a JSON request containing a list of strings is unmarshalled, the resulting value of request.Prompt is a []interface{}. The checkPromptType function only checked for string and []string, so its returning false when request.Prompt is a []interface{} even if all elements within that slice are strings, because []interface{} is not the same type as []string.

This change allows better validation of prompt types, accommodating the scenario where the prompt is provided as a list of strings in an interface{} slice.

Describe your solution
The solution involves adding a new type check for []interface{} in the checkPromptType function. The code checks if prompt is of type []interface{} and, if so, iterates over the slice to ensure all elements are strings. If any element is not a string, the validation fails. This logic is integrated alongside the existing checks for string and []string types. This enhancement ensures that the function properly handles various input types for prompts and raises the ErrCompletionRequestPromptTypeNotSupported error if an unsupported type is provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.86%. Comparing base (774fc9d) to head (413dc3a).
Report is 67 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #885      +/-   ##
==========================================
+ Coverage   98.46%   98.86%   +0.40%     
==========================================
  Files          24       26       +2     
  Lines        1364     1761     +397     
==========================================
+ Hits         1343     1741     +398     
+ Misses         15       14       -1     
  Partials        6        6              

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[AyushSawant18588]

@sashabaranov Can you please look into this?

[johnugeorge]

@sashabaranov Can you review? Currently, completions api is not working due to this bug

[sashabaranov]

@AyushSawant18588 thank you for the PR! Could we please use a less nested version of this with early returns? Something like this https://go.dev/play/p/cS9jrYnWrvN

[AyushSawant18588]

Yeah sure I will check and update the PR

[AyushSawant18588]

I have updated the PR @sashabaranov, can you please take a look?

[sashabaranov]

Thank you!

[AyushSawant18588]

@sashabaranov Can you please create a release? I need to upgrade my go-openai client with the above changes. Thanks!

[sashabaranov]

@AyushSawant18588 sure, I was waiting for #882 to be merged, but it seems it would take some time!

Note: you can always swap to your fork as well!