Support JsonExtensionData in TypeScript clients

[Sharparam]

See also: RicoSuter/NSwag#1541 (comment)

Currently, the generated C# clients support the JsonExtensionData attribute, but in the TypeScript clients it's simply ignored.

We discovered this when troubleshooting why data was missing in ProblemDetails in ASP.NET Core.

From a bit of debugging, it seems the following might be part of a solution:

Add the missing properties to ClassTemplateModel in NJsonSchema.CodeGeneration.TypeScript:

public bool HasAdditionalPropertiesType =>
    !_schema.IsDictionary &&
    !_schema.ActualTypeSchema.IsDictionary &&
    !_schema.IsArray &&
    !_schema.ActualTypeSchema.IsArray &&
    (_schema.ActualTypeSchema.AllowAdditionalProperties ||
    _schema.ActualTypeSchema.AdditionalPropertiesSchema != null);

public string AdditionalPropertiesType => HasAdditionalPropertiesType ? "any" : null;

Add code to the Liquid templates for property:

{% if HasAdditionalPropertiesType %}
    additionalProperties?: { [key: string]: {{ AdditionalPropertiesType }}; } | undefined;
{% endif %}

And code in the init method to populate it:

{% if HasAdditionalPropertiesType %}
            this.additionalProperties = {} as {{ AdditionalPropertiesType }};
            for (const [key, value] of Object.entries(_data)) {
                if (!this.hasOwnProperty(key))
                    this.additionalProperties![key] = value;
            }
{% endif %}

There's probably a bunch of things here to take into consideration that I have missed from my basic glance over the various code generators. In my limited testing at least it seems to produce the expected results.

Additionally, System.Text.Json's JsonExtensionData attribute would need additional support. I think that would be part of the separate issues about supporting System.Text.Json though?

[cbalisky]

The TypeScript Liquid template has the logic already. It's currently only used when HasIndexerProperty is true. I've created a PR that adds AllowAdditionalProperties and AdditionalPropertiesSchema to the check #1412

[AlbertoSadoc]

Hello @Sharparam, did you manage to get this working? I am struggling to deserialize a ProblemDetails.

Using nswag v13.18.2
nswag openapi2tsclient /runtime:Net60 /input:swagger.json /output:src/api/client.generated.ts /template:axios /operationGenerationMode:MultipleClientsFromPathSegments /generateTypeCheckFunctions:true

and get the following:

export class ProblemDetails implements IProblemDetails {
  type?: string | undefined;
  title?: string | undefined;
  status?: number | undefined;
  detail?: string | undefined;
  instance?: string | undefined;
  readonly extensions?: { [key: string]: any };

  constructor(data?: IProblemDetails) {
    if (data) {
      for (var property in data) {
        if (data.hasOwnProperty(property)) (<any>this)[property] = (<any>data)[property];
      }
    }
  }

  init(_data?: any) {
    if (_data) {
      this.type = _data["Type"];
      this.title = _data["Title"];
      this.status = _data["Status"];
      this.detail = _data["Detail"];
      this.instance = _data["Instance"];
      if (_data["Extensions"]) {
        (<any>this).extensions = {} as any;
        for (let key in _data["Extensions"]) {
          if (_data["Extensions"].hasOwnProperty(key)) (<any>(<any>this).extensions)![key] = _data["Extensions"][key];
        }
      }
    }
  }

  static fromJS(data: any): ProblemDetails {
    data = typeof data === "object" ? data : {};
    let result = new ProblemDetails();
    result.init(data);
    return result;
  }

  toJSON(data?: any) {
    data = typeof data === "object" ? data : {};
    data["Type"] = this.type;
    data["Title"] = this.title;
    data["Status"] = this.status;
    data["Detail"] = this.detail;
    data["Instance"] = this.instance;
    if (this.extensions) {
      data["Extensions"] = {};
      for (let key in this.extensions) {
        if (this.extensions.hasOwnProperty(key)) (<any>data["Extensions"])[key] = (<any>this.extensions)[key];
      }
    }
    return data;
  }
}

export interface IProblemDetails {
  type?: string | undefined;
  title?: string | undefined;
  status?: number | undefined;
  detail?: string | undefined;
  instance?: string | undefined;
  extensions?: { [key: string]: any };
}

so the indexer isn't anywhere but the extensions property