[BUG] [typescript-angular] Query param key is undefined when using queryParamObjectFormat=json

Created by: thccorni

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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Generating the client with queryParamObjectFormat set to json breaks the query string resulting in request urls like: https://example.com/pizzas?undefined={someJSON} instead of https://example.com/pizzas?filter={someJSON}.

openapi-generator version

v5.0.0-beta2

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: 'Sample-API'
  version: '1.0.0'
paths:
  /pizzas:
    get:
      parameters:
        - name: filter
          in: query
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PizzaFilter'
      responses:
        200:
          description: Delicious pizzas
          content:
            application/json:
              schema:
                type: array
                items:
                  type: string

components:
  schemas:
    PizzaFilter:
      type: object
      additionalProperties: true

Generation Details

Steps to reproduce

npx @openapitools/openapi-generator-cli version-manager set 5.0.0-beta2
npx @openapitools/openapi-generator-cli generate -i spec.yaml -g typescript-angular -o ./generated --additional-properties=queryParamObjectFormat=json

Related issues/PRs

Suggest a fix

I think the Problem is that the key parameter is not passed here: https://github.com/OpenAPITools/openapi-generator/blob/d8ba49b267d7bfe9d558631d2888a6d54a1c3bf8/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache#L97

Therefore it is undefined here: https://github.com/OpenAPITools/openapi-generator/blob/d8ba49b267d7bfe9d558631d2888a6d54a1c3bf8/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache#L111

A possible fix could be to move the distinction of the query param format to addToHttpParams instead of addToHttpParamsRecursive

private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
    if (typeof value === "object" && value instanceof Date === false) {
        {{#isQueryParamObjectFormatJson}}
        httpParams = httpParams.append(key, JSON.stringify(value));
        {{/isQueryParamObjectFormatJson}}
        {{^isQueryParamObjectFormatJson}}
        httpParams = this.addToHttpParamsRecursive(httpParams, value);
        {{/isQueryParamObjectFormatJson}}
    } else {
        httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
    }
    return httpParams;
}

private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
    if (value == null) {
        return httpParams;
    }

    if (typeof value === "object") {
        if (Array.isArray(value)) {
            (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
        } else if (value instanceof Date) {
            if (key != null) {
                httpParams = httpParams.append(key,
                    (value as Date).toISOString(){{^isDateTime}}.substr(0, 10)){{/isDateTime}};
            } else {
                throw Error("key may not be null if value is Date");
            }
        } else {
            Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
                httpParams, value[k], key != null ? `${key}{{#isQueryParamObjectFormatDot}}.{{/isQueryParamObjectFormatDot}}{{#isQueryParamObjectFormatKey}}[{{/isQueryParamObjectFormatKey}}${k}{{#isQueryParamObjectFormatKey}}]{{/isQueryParamObjectFormatKey}}` : k));
        }
    } else if (key != null) {
        httpParams = httpParams.append(key, value);
    } else {
        throw Error("key may not be null if value is not object or array");
    }
    return httpParams;
}