Question

我有两个Observable，第二个Observable（convertScore $）需要使用第一个Observable的返回值（displayScore $）。

我使用do运算符可以组合两个主要的Observerbles，但是第二个do运算符（函数：fakeImgSrcFromHttp）在第一个Observable（displayScore $）内部不能执行，为什么??

我预计结果是：

隐蔽得分： 100 To OtherData
将ImgSrc绑定到HtmlTag：它是一个src字符串
显示分数： 100
完整

＆＃13;

/***** From A Service *****/
var convertScore$ = fakeScoreFromHttp()
              .do(score => covertScoreToOtherData(score))
              .do(score => {
                fakeImgSrcFromHttp(score)
                .do(imgSrc => {
                  console.log("bind ImgSrc to HtmlTag:" + imgSrc);
                })
              });

function fakeScoreFromHttp(){
  return Rx.Observable.of(100);
}

function fakeImgSrcFromHttp(score){
  // ToDo : if score is something, then do else do....
  
  // return
  return Rx.Observable.of("it's a src string");
}

function covertScoreToOtherData(score){
  console.log("covert score:" + score + " To OtherData")
}

/***** From B Service *****/
var displayScore$ = convertScore$.do(score => displayScore(score));
                
displayScore$.subscribe({
    // next: (value) => { },
    // error: (err) => { console.log('Error: ' + err); },
    complete: (score) => { 
      console.log('complete'); 
    }
});

function displayScore(score){
  console.log("display score:"+score);
}

＆＃13;

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/5.0.1/Rx.js"></script>

＆＃13;

Answer 1

使用运算符 - flatMap

var example = fakeScoreFromHttp()
          .do(score => covertScoreToOtherData(score))
          .flatMap(score => {
          return  fakeImgSrcFromHttp(score)
            .do(imgSrc => {
              console.log(imgSrc);
            })
          });

example.subscribe({
// next: (value) => { console.log(value); },
// error: (err) => { console.log('Error: ' + err); },
// complete: () => { console.log('complete'); }
});


function fakeScoreFromHttp(){
return Rx.Observable.of(100);
}

function fakeImgSrcFromHttp(score){
  // ToDo : if score is something, then do else do....

 // return
return Rx.Observable.of("it's a src string");
}

function covertScoreToOtherData(score){
 console.log("covert score:" + score + " To OtherData")
}

Answer 2

current_user.reload

/***** From A Service *****/
var convertScore$ = fakeScoreFromHttp()
              .do(score => covertScoreToOtherData(score))
              .flatMap(score => {
               return fakeImgSrcFromHttp(score)
                .do(imgSrc => {
                  console.log("bind ImgSrc to HtmlTag:" + imgSrc);
                })
              });

function fakeScoreFromHttp(){
  return Rx.Observable.of(100);
}

function fakeImgSrcFromHttp(score){
  // ToDo : if score is something, then do else do....
  
  // return
  return Rx.Observable.of("it's a src string");
}

function covertScoreToOtherData(score){
  console.log("covert score:" + score + " To OtherData")
}

/***** From B Service *****/
var displayScore$ = convertScore$.do(score => displayScore(score));
                
displayScore$.subscribe({
    // next: (value) => { },
    // error: (err) => { console.log('Error: ' + err); },
    complete: (score) => { 
      console.log('complete'); 
    }
});

function displayScore(score){
  console.log("display score:"+score);
}

如何组合两个observable并使用第一个Observable返回值

2 个答案: