help typing Request query with object

[GregLtrnr]

Hello, I'm running into a problem typing filter query using the express router with my request controller

//router.ts
import { listArticles } from "./controller";

const router = express.Router();

router.get("/", listArticles);

//controller.ts

export interface GetArticleListRequestQueryParams {
  page: string;
  pageSize: string;
  [key: string]: string | number | object;
}

export async function listArticles(req: Request<unknown, unknown, unknown, GetArticleListRequestQueryParams>, res: Response){
  try{
      const parameters = req.query
      const page: number = Number(parameters.page) ?? 1;
      const pageSize: number = Number(parameters.pageSize) ?? 10;
      
      if (parameters?.filter && typeof parameters.filter === "object" && "categories" in parameters.filter) {
      //...
      }
  }
}

So basically, I want to be able to get custom filters in my request, like this: GET /article?page=1&pageSize=5&filter[categories]=categId

Using this request, using a console log on req.query, i get this:

//{ page: '1', pageSize: '5', filter: { categories: 'categId' } }

This is exactly what I want, but the issue here is for typing the query param in my req argument, the param I put GetArticleListRequestQueryParams is giving me an error in the router.ts:

No overload matches this call.
  The last overload gave the following error.
    Argument of type '(req: Request<unknown, unknown, unknown, GetArticleListRequestQueryParams, Record<string, any>>, res: Response<any, Record<string, any>>) => Promise<...>' is not assignable to parameter of type 'RequestHandlerParams<ParamsDictionary, unknown, unknown, ParsedQs, Record<string, any>>'.
      Type '(req: Request<unknown, unknown, unknown, GetArticleListRequestQueryParams, Record<string, any>>, res: Response<any, Record<string, any>>) => Promise<...>' is not assignable to type 'RequestHandler<ParamsDictionary, unknown, unknown, ParsedQs, Record<string, any>>'.
        Types of parameters 'req' and 'req' are incompatible.
          Type 'Request<ParamsDictionary, unknown, unknown, ParsedQs, Record<string, any>>' is not assignable to type 'Request<unknown, unknown, unknown, GetArticleListRequestQueryParams, Record<string, any>>'.
            Types of property 'query' are incompatible.
              Type 'ParsedQs' is missing the following properties from type 'GetArticleListRequestQueryParams': page, pageSizets(2769)
index.d.ts(153, 5): The last overload is declared here.

By getting a look to Request.ReqQuery, I need to provide a ParsedQS type, which look like this:

    interface ParsedQs {
        [key: string]: undefined | string | string[] | ParsedQs | ParsedQs[];
    }

So my question is, how can I give objects type to the query params for my filter attribute without making it throw an error ? (I tried putting just string, but then I get a never type on my if (parameters?.filter && typeof parameters.filter === "object" && "categories" in parameters.filter).

The only solution I found is to give the type on the const parameters with a as GetArticleListRequestQueryParams but it's not clean at all :/

thanks for the help 🔥