[BUG][typescript-axios] Broken client

[vmstarchenko]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?

Description

openapi-generator create broken client for attached schema.
Errors:

• Types error:

  > 75 |         apiProblemCreate: async (tags: Array<ProblemTagRequest>, options: any = {}): Promise<RequestArgs> => {
       |                                              ^ // ProblemTagRequest does not exist
    76 |             // verify required parameter 'tags' is not null or undefined
    77 |             assertParamExists('apiProblemCreate', 'tags', tags)
    78 |             const localVarPath = `/api/problem/`;

• DataForm usage error

92 |  localVarFormParams.append(tags.join(COLLECTION_FORMATS.csv));
                               ^ // here should be append('tags', tags...

• wrong array usage

92 |    localVarFormParams.append(tags.join(COLLECTION_FORMATS.csv));
                                         ^ // join returns [object Object],[object Object],

openapi-generator version

5.0.1
latest dev version

OpenAPI declaration schema

https://gist.github.com/vmstarchenko/9671d45499a66d73b6746e69168c6cc5

Generation Details

java -jar ./openapi-generator-5.0.1/modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -i ./api-spec.yaml -g typescript-axios --additional-properties=useSingleRequestParameter=true -o ./client/typescript-axios

Generated client:
https://gist.github.com/vmstarchenko/5128a715559fcb065649b37b316f3be9

Steps to reproduce

Generate typescript-axios client with useSingleRequestParameter additional property and attached schema

Related issues/PRs

Suggest a fix

[vmstarchenko]

Please, reopen this issue. Only second problem (with DataForm usage error) has been solved. There are still two other problems:

• wrong array usage tags.join(COLLECTION_FORMATS.csv)); returns [object Object],[object Object]
• Types error with Array<...Request> type

[lumoe]

I can confirm this error behavior, tested it with latest version 5.1.1 with the same error message Property 'join' does not exist on type 'Set'.

Sadly I won't be able to track this issue down within the openapi-generator source code.

For anyone experiencing this issue, my workaround is to cast the affected variable to any.
assignedUsers.join(COLLECTION_FORMATS['csv']) to (assignedUsers as any).join(COLLECTION_FORMATS['csv'])