如何在拦截器Angular中获取请求的查询参数

Question

I want to get the query params from an get request. Interceptor code is this way,

export class FixtureInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
       return next.handle(req);
  }
}

i tried to get the params using get method like this ,

req.params.get('category');

but it returns me null always. My api call is this way ,

getValue() {
     return this.http.get('http://139.49.10.175:3000/laundryItems?category=2&type=4');
}

i need value of category and type from above API call

Answer 1

Apparently params directly putted in url doesn't appear in req.params , this one should work:

  getValue() {
    return this.http.get('http://139.49.10.175:3000/laundryItems', {params: {category: '2', type: '4'}});
  }

Answer 2

Well... here we are again... HttpParams documentation states object is immutable. Therefore, in order to build the collection we must do something like:

let params = new HttpParams().set("categoryName", "Cars");
if (search.length >= 2) {
  params = params.append("search", search);
}

Adding to http.get must take this form:

this.http.get<Product[]>(`${this.baseUrl}products`, { params }).subscribe(result => {
  this.products = result;
}, error => {
  console.error(error)
}); 

IMPORTANT: The wrapping of params in brace-brackets is required - especially if you want to retrieve the params, like by some interceptor - for example:

let search = request.params.get("search");

Also, refer to the section about using HttpParams in this article .