Angular rooting front-end <-> back-end Cant root findByKey() in front end

So, i use postman to test if my findByKey() in back-end works and in fact it works. However, when i try it in front-end services i cant return an object. it returns me an observable everytime i console.log.

Sample 1:
Back-end root

public async findByKey() {
            this.app.get("/Path/Contains/:expression", (async (req: Request, res: Response) => {
                var pathListDTO = await this.service.findByKey(req);
              
                if (!pathListDTO) {
                    res.status(400).send("The path was not found!");
                } else {
                    res.json(pathListDTO);
                }
            }));
        }

Sample2:
Front-end root

 findByKey(key: string) {
return this.http.get(`${baseUrl}/Contains/?key=${key}`);

}

I dont know if the problem is the contains but in back-end works in postman so idk

here is my baseUrl

const baseUrl = 'http://localhost:9001/path';

Source: Angular Questions