query is class member of Wall, Guard, Shield and Controller. It is used to get the query string value.

e.g - Conside the url - abc.com/?userid=5&name=ujjwal

There are two variables in query string - userid and name . We can use query to access those value.

export class DefaultController extends Controller {

    async default() {
        const userId = this.query.userid;
        const name = this.query.name;

        return textResult(`userId is ${userId} & name is ${name}`);