Angular 4 http获取查询参数

getQuotes(): Observable<Quote[]> {
    return this.http.get(this.url)
        .map((res: Response) => res.json())
        .catch((error: any) => Observable.throw(error.json().error || 'Server error'));
}

现在我要向this.url添加查询参数,并且url没有改变

getQuotes2(): Observable<Quote[]> {
    let myParams  = new URLSearchParams();
    myParams.append('author','authorName');
    myParams.append('catid','123');
    let options = new RequestOptions({ params: myParams });

    return this.http.get(this.url,options )
        .map((res: Response) => res.json())
        .catch((error: any) => Observable.throw(error.json().error || 'Server error'));
}

我检查过devtools.缓存已关闭.我已尝试使用RequestOptions {search：myParams}并返回this.http.get(this.url,{params：myParams})
在我不看的地方,我看到字符串连接.这些参数是optinal,我将它们附加条件.