如何從角2中的JSON數據中獲取數組

Question

我正在開發角2中的應用程序。我創建了一個服務，現在我想從json數據中獲取特定的數組。

我有這樣

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

這是返回所有JSON數據服務代碼，但我想唯一的「項目」陣列從JSON獲取。

JSON代碼

{ 
    "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

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)); 
    }) 
} 

Answer 2

使用JSON轉換的方法，

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); 
}