fix: allow array query parameter for a single value

[mrmodise]

PR fixes an issue where by passing only a single query parameter throws an error with code INVALID_PARAMETER_VALUE and message should be array

Fixes: #6514

Checklist

• DCO (Developer Certificate of Origin) signed in all commits
• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• API Documentation in code was updated
• Documentation in /docs/site was updated
• Affected artifact templates in packages/cli were updated
• Affected example projects in examples/* were updated

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[bajtos]

Thank you @mrmodise for the pull request ❤️

I'd like to discuss several implementation & testing details, PTAL at my comment below.

I'd also like to discuss one important edge case: let's say we have a parameter accepting a two-dimensional array (an array of an arrays of strings). How are we going to coerce such values? Request values to consider:

• a "full" value: [[1, 2], [3, 4]]
• a single item at top level, containing an array: [[1, 2]]
• multi values at top level, containing a single time array: [[1], [3]]
• a single item array at top level containing a single item array: [[1]]

Can you please check how is swagger-ui (API Explorer) converting such values into query string parameters and ensure that our coercion code handles them correctly?

Using qs with {arrayFormat: 'repeat'}:

> qs.stringify({foo: [1]}, {arrayFormat: 'repeat'})
'foo=1' // this is your use case, right?
> qs.stringify({foo: [[1,2],[3,4]]}, {arrayFormat: 'repeat'})
'foo=1&foo=2&foo=3&foo=4' // uh oh, information was lost :(
> qs.stringify({foo: [[1,2]]}, {arrayFormat: 'repeat'})
'foo=1&foo=2'
> qs.stringify({foo: [[1],[3]]}, {arrayFormat: 'repeat'})
'foo=1&foo=3'
> qs.stringify({foo: [[1]]}, {arrayFormat: 'repeat'})
'foo=1'

Based on the above, I am not sure if it's a good idea to support coercion of singular values into an array for all array types. I guess it should be fine if we limit coercion only to itemType of string, number or boolean as suggested by @raymondfeng.

[mrmodise]

• [[1, 2], [3, 4]]

Interesting, below are the results of these tests:

1. [[1, 2], [3, 4]] results in [ '1', '2', '3', '4' ]
2. [[1, 2]] results in [ '1', '2' ]
3. [[1], [3]] results in [ '1', '3' ]
4. [[1]] results in [ '1' ]

@bajtos @raymondfeng done the changes as requested. Thanks

[bajtos]

Looks pretty good now.

I am little bit concerned about handling parameters accepting an array of arrays, but I guess that's something we can fix later, if there is ever any user demand for that.

@raymondfeng can you please review the new version too?

[raymondfeng]

@mrmodise PR is landed. Thank you for the contribution with great patience. 🥇