角度 6 等待回复

Question

var data2 = { data1Id: 0 };

postData(){

this._service1.save(data1).subscribe(res => {
          this.data2.data1Id = res.Data.Id; //res.Data.Id has valid data
     });

     this._service2.save(data2).subscribe(res => {
          console.log(this.data2.data1Id); //"this.data2.data1Id = 0" can't get value from service1
     });
}

如何从第一个服务或某些功能获取数据，让我解决问题运行调用服务序列。感谢收看！

Answer 1

使用 async/await 非常适合您的情况。由于 await 关键字，它将帮助您使您的代码更具可读性并抽象异步部分

aync post(){

    const res1 = await this._service1.save(this.data1).toPromise();
    const res2 = await this._service2.save(res1).toPromise();
    console.log('here is my data 2 ' + res2);

    return 'what you want, can be res1 or res2 or a string';
}

怎么称呼它？

this.myService.post().then( (whatYouWanted) => {
  console.log(whatYouWanted); // what you want, can be res1 or res2 or a string
});

Answer 2

使用 flatMap 链接 observables。

this._service1.save(data1).flatMap(res => {
      this.data2.data1Id = res.Data.Id; //res.Data.Id has valid data
      return this._service2.save(data2).
 }).subscribe(res => {
      console.log(this.data2.data1Id); //"this.data2.data1Id = 0" can't get value from service1
 });

Answer 3

this._service1.save(data1).flatMap(res => {
      this.data2.data1Id = res.Data.Id; //res.Data.Id has valid data
      return this._service2.save(data2);
 }).subscribe(res => {
      console.log(this.data2.data1Id); //"this.data2.data1Id = 0" can't get value from service1
 });

你可以使用 flatMap 并返回第二个 observable 来链接它们。 文档：http://reactivex.io/documentation/operators/flatmap.html