如何从 Angular 2 中的 JSON 数据获取数组

Question

我正在 angular 2 中开发一个应用程序。我创建了一个服务，现在我想从 json 数据中获取特定的数组，我可以如何获取。

我有这样的服务代码

getProjects(): Promise<Project>{
return this.getData()
  .toPromise()
  .then(response => response.json())
  .catch((error: string) => console.log(error));
}

这将返回所有 json 数据，但我只想从 json 中获取“Projects”数组。

JSON 代码

{
   "features":[],
   "posts":{},
   "Projects":[
    {
        "id":"proj-1",
        "name":"Design for creative",
        "meta":{
            "date":"03 November, 2016",
            "url":"http://www.pixelsocket.com",
            "skills":[
                "ui design",
                "programming",
                "marketing"
            ]
        },
        "images":[
            "assets/images/design-creative-01.jpg",
            "assets/images/design-creative-02.jpg",
            "assets/images/design-creative-03.jpg",
            "assets/images/design-creative-04.jpg"
        ],
        ...
}

更新

getProject(id: string): Promise<Project>{
 const url = `${this.getProjects()}/${id}`; // can i call getProjects() method here

 return this.http.get(url)
   .toPromise()
   .then(response => response.json())
   .catch((error: string) => console.log(error));
}

Answer 1

使用一种方法来转换json，

private extractData(res: any) {
        if (res.status < 200 || res.status >= 300) {
            throw new Error('Bad response sttus:' + res.status);
        }
        let serviceData = res.json().projects;
        return serviceData || {};
    }

getProjects(): Promise<Project>{
return this.getData()
  .toPromise()
  .map(this.extractData);
}

Answer 2

getProjects(): Promise<Project>{
return this.getData()
  .toPromise()
  .then(response => response.json().projects) // <<< added .projects
  .catch((error: string) => console.log(error));
}

getProject(id: string): Promise<Project>{
  return this.getProjects()
  .then(p => `${p}/${id}`) // no idea where `id` should come from
  .then(url => {
    return this.http.get(url)
   .toPromise()
   .then(response => response.json())
   .catch((error: string) => console.log(error));
  })
}