RxJs捕获错误并继续 [英] RxJs catch error and continue

问题描述

我有一个要解析的项目列表，但其中一个项目的解析可能会失败。

I have a list of items to parse, but the parsing of one of them can fail.

什么是Rx-Way来捕获错误但是继续执行序列

What is the "Rx-Way" to catch error but continue executing the sequence

代码示例：

var observable = Rx.Observable.from([0,1,2,3,4,5])
.map(
  function(value){
      if(value == 3){
        throw new Error("Value cannot be 3");
      }
    return value;
  });

observable.subscribe(
  function(value){
  console.log("onNext " + value);
  },
  function(error){
    console.log("Error: " + error.message);
  },
  function(){
    console.log("Completed!");
  });

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/4.0.6/rx.all.js"></script>

我想要做什么非Rx-Way：

What I want to do in a non-Rx-Way:

var items = [0,1,2,3,4,5];

for (var item in items){
  try{
    if(item == 3){
      throw new Error("Value cannot be 3");
    }
    console.log(item);
  }catch(error){
     console.log("Error: " + error.message);
  }
}

提前致谢

推荐答案

我建议您使用 flatMap （现在 mergeMap 在rxjs版本5中，如果你不关心它们，它会让你崩溃错误。实际上，您将创建一个内部Observable，如果发生错误，可以吞下它。这种方法的优点是你可以将运算符链接在一起，如果管道中的任何地方发生错误，它将自动转发到catch块。

I would suggest that you use flatMap (now mergeMap in rxjs version 5) instead, which will let you collapse errors if you don't care about them. Effectively, you will create an inner Observable that can be swallowed if an error occurs. The advantage of this approach is that you can chain together operators and if an error occurs anywhere in the pipeline it will automatically get forwarded to the catch block.

var observable = Rx.Observable.from([0, 1, 2, 3, 4, 5])
  .flatMap((value) =>          
    Rx.Observable.if(() => value != 3,
      Rx.Observable.just(value),
      Rx.Observable.throw(new Error("Value cannot be 3")))
    //This will get skipped if upstream throws an error
    .map(v => v * 2)
    .catch((err) => {
      console.log("Caught Error, continuing")
      //Return an empty Observable which gets collapsed in the output
      return Rx.Observable.empty();
    })
  );

observable.subscribe(
  (value) => console.log("onNext " + value), (error) => console.log("Error: " + error.message), () => console.log("Completed!")
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/4.0.6/rx.all.js"></script>

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