角度2可观察到可观察[] [英] Angular 2 Observable to Observable []

问题描述

不确定标题是否准确，不确定确切的术语.

Not sure if the title is accurate as not sure of the exact terminology.

假设我有一些类似下面的代码.

Suppose I have some code like the the below.

当我使用第一种方法加载单个资源时，我可以创建一个丰富模型类的实例，该类在传递给map(...)的函数中包装/修饰普通的JS对象.

When I load an individual resource using the first method I can create an instance of a rich model class which wraps/decorates the plain JS object in the function passed to map(...).

在第二种方法中，如果响应是一个Course对象数组，如何实现相同的目的?

How can I achieve same in the second method where the response is an array of Course objects?

@Injectable()
export class CourseService {

  constructor(private restangular: Restangular) {

  }

  public getCourse(id: number): Observable<any> {
    return this.restangular.one("courses", id).get().map(response =>
      new Course(response)
    );
  }

  public getAllCourses(): Observable<any> {
    return this.restangular.all("courses").getList().map(response => {
      //an array of courses
      console.log(response);
    });
  }
}

推荐答案

由于第二种方法接收到数组，因此可以使用 Array.map()迭代数组的值并进行转换每个值进入 Course 实例:

Since the second method receives an array, you can use Array.map() to iterate on the values of the array and convert each value into a Course instance:

public getAllCourses(): Observable<any> {
  return this.restangular.all("courses").getList().map(response => {
    return response.map(courseData => new Course(courseData));
  });
}

此代码可能会令人困惑，因为:

This code can be confusing because:

• 第一个 .map()是 Observable.map()(来自RxJS库).
• 第二个 .map()是 Array.map()(普通JavaScript).

• The 1st .map() is Observable.map() (from RxJS library).
• The 2nd .map() is Array.map() (plain JavaScript).

为简便起见，您可以将方法主体写在一行上(这样就避免了内部的 return ):

For brevity, you could write the method body on a single line (thus avoiding the inner return):

public getAllCourses(): Observable<any> {
  return this.restangular.all("courses").getList().map(response => response.map(courseData => new Course(courseData)));
}

但是它有点难读.:)

这篇关于角度2可观察到可观察[]的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！