Openapi-generator: [BUG][typescript-inversify] Type mismatch between service model and HttpClient requirement

[siada]

Bug Report Checklist

• [x] Have you provided a full/minimal spec to reproduce the issue?
• [x] Have you validated the input using an OpenAPI validator (example)?
• [x] What's the version of OpenAPI Generator used?
• [x] Have you search for related issues/PRs?
• [ ] What's the actual output vs expected output?
• [ ] [Optional] Bounty to sponsor the fix (example)

Description

When using typescript in strict mode, the code won't compile if your spec has an optional requestBody because the HttpClient defines body as {} which means 'any except null or undefined'

openapi-generator version

4.1.0

Steps to reproduce

Generated service method:

    public apiAccountLoginPost(loginViewModel?: LoginViewModel, observe?: 'body', headers?: Headers): Promise<LoginViewModelResult>;
    public apiAccountLoginPost(loginViewModel?: LoginViewModel, observe?: 'response', headers?: Headers): Promise<HttpResponse<LoginViewModelResult>>;
    public apiAccountLoginPost(loginViewModel?: LoginViewModel, observe: any = 'body', headers: Headers = {}): Promise<any> {

HttpClient:

    post(url: string, body: {}|FormData, headers?: Headers): Observable<HttpResponse> {
        return this.performNetworkCall(url, "POST", this.getJsonBody(body), this.addJsonHeaders(headers));
    }

Error:

Related issues/PRs

3607

Suggest a fix

I believe changing the {} to any in the HttpClient will resolve this, however I don't know enough about typescript to understand the impact this may have

I'm happy to organise the PR for this if you agree with this change

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[macjohnny]

how about changing it to body?: Object|FormData and also adapting
https://github.com/siada/openapi-generator/blob/b54a5266ac9824306e5904554275d809dcd66057/modules/openapi-generator/src/main/resources/typescript-inversify/HttpClient.mustache#L40
to handle undefined/null values?

[macjohnny]

@gualtierim what is your opinion?

[siada]

For handling the undefined/null values should getJsonBody return null, empty string, or {} ?

[macjohnny]

For handling the undefined/null values should getJsonBody return null, empty string, or {} ?

good question, I guess undefined ?

[gualtierim]

I agree to change the signature of httpClient with Object|FormData. getJsonBody should return undefined, I will try it the next week

[deluksic]

Also, addJsonHeaders's headers parameter should be optional.

[siada]

@deluksic I already fixed that in PR #3607 this issue has been opened as a discussion from that

[siada]

@gualtierim Did you manage to get around to trying the solution out yet?