Question

我有两个选择下拉列表。第一个列出域，第二个列出属于域。当我选择域时，将发送域的ID。 API由Laravel生成的json提供。如果categories对象中存在匹配项，则应返回那些匹配项（如果发送的id等于activity_domain_id）。

从应用程序组件中选择方法

seleDomain(domainId: number) {
                this.formsService.getDomains()
                .then(categories => this.categories.filter(item => item.activity_domain_id === domainId))
                .catch(error => this.error = error);
        }

这就是Categories和Domain类的样子：

export class Domain {
    id: number;
    user_id: number;
    name: string;
}

export class Categories {
  id: number;
  activity_domain_id: number;
  name: string;
}

从服务组件获取域并获取类别方法

  getDomains(domain: Domain): Promise<Domain[]> {
    return this.http.get(this.domainsUrl)
                    .toPromise()
                    .then(this.extractData)
                    .catch(this.handleError);
  }

  getCategories(userId: number): Promise<Categories[]> {
    return this.http.get(this.categoriesUrl)
            .toPromise()
            .then(this.extractData)
            .catch(this.handleError);
  }

 private extractData(res: Response) {
    let body = res.json();
    return body || { };
 }

以下是extractData返回的域json如下所示：

[{"id":1,"user_id":1,"name":"I.T","updated_at":"2016-10-06 14:07:55","created_at":"2016-03-03 19:28:54"},{"id":3,"user_id":1,"name":"Management","updated_at":"2016-10-06 16:27:18","created_at":"2016-08-09 15:10:34"}]

以下是extractData返回的类别json如下所示：

[{"id":9,"activity_domain_id":1,"name":"Front end developer","updated_at":"2016-09-06 10:19:23","created_at":"2016-09-05 15:21:08"},{"id":10,"activity_domain_id":1,"name":"Back end developer","updated_at":"2016-09-05 15:21:20","created_at":"2016-09-05 15:21:20"}]

进行过滤时，不会返回匹配项。

使用Promise使用Angular 2级联下拉列表

0 个答案: