Question

我导入了'rxjs / add / operator / toPromise';

在我的Ts文件中，我有类似的东西：

onChange(categoryid) {
//console.log('testing')
this.productService.getProductsOncategory(categoryid).subscribe(data => {
  if (data.success) {

    console.log('Products obtained');
  } else {
    console.log('Not obtained!');
  }
 });
}

我收到错误：

属性'subscribe'在'Promise'类型中不存在。

getProductsOncategory(category_id) {

let catUrl = "API URL"
let headers = new Headers();
headers.append('Content-Type', 'application/json');
let catIdObj = JSON.stringify({ category_id: category_id })
return this.http.post(catUrl, catIdObj, { headers: headers })
  .toPromise()
  .then((response: Response) => response.json().data)
  //.map((response: Response) => response.json())
  //.do(data => console.log(JSON.stringify(data)))
  .catch(this.handleError);

}

如果必须使用'then（数据=＆gt;'...

，如何更改代码段

Answer 1

subscribe方法用于'Observable'，因此您只需返回一个Observable Object。然后像这样做你想做的事情

getProductsOncategory(category_id): Observable<Response>{

        let catUrl = "API URL"
        let headers = new Headers();
        headers.append('Content-Type', 'application/json');
        let catIdObj = JSON.stringify({ category_id: category_id })
        return this.http.post(catUrl, catIdObj, { headers: headers })
  }

this.productService.getProductsOncategory(categoryid)
    .map(response => response.json().data)
    .subscribe(data => doSomething(data),err => catchErr(err));

Answer 2

只需映射http请求并将其返回。无需创建新承诺

getProductsOncategory(category_id) {

    let catUrl = "API URL"
    let headers = new Headers();
    headers.append('Content-Type', 'application/json');
    let catIdObj = JSON.stringify({
        category_id: category_id
    })

    return this.http.post(catUrl, catIdObj, {
            headers: headers
        })
        .map((res: Response) => res.json());
}

Promise <any>类型上不存在Angular 2属性订阅

2 个答案: