Query Params

Reading the ?name=value pairs a client appends to the URL

Overview

Query params are read the same way path params are, using queryParam() instead of pathParam(). Nothing needs to be declared in paths — any client can append any query string to any path, so queryParam() is available on every resource regardless of what its paths look like.

Objectives

To gain familiarity with:

reading a query param with queryParam(); and
how a repeated param resolves.

Reading a Query Param


import { Resource } from "@drashland/drash/modules/http.polyfill.js";
 
class Users extends Resource {
  paths = ["/users"];
 
  // Node hands the chain a context object, so `params` is attached to that
  // rather than to a Web `Request`, and you write the response instead of
  // returning one.
  GET(context) {
    const page = context.params.queryParam("page");
 
    context.response.end(`page=${page}`);
  }
}

A param the client did not send comes back as undefined rather than throwing, so check the value instead of catching an error.

Repeated Params

A client can send the same name more than once. queryParam() returns the first value:


// GET /users?sort=asc&sort=desc
request.params.queryParam("sort"); // "asc"

Verification

With a resource whose paths are ["/users"] running on localhost:1447:


curl "http://localhost:1447/users?page=2"         ->  page=2
curl "http://localhost:1447/users?x=1&page=2"     ->  page=2
curl "http://localhost:1447/users"                ->  page=undefined

Position does not matter — a param reads the same whether it is first in the query string or last.