Angular Promises and Chaining：如果链存在业务数据错误，如何打破链 [英] Angular Promises and Chaining: How to break a chain if it has business data errors

问题描述

我以为我这些都已经在以前的项目中找到了所有这些......显然不是。

目标：接受调用其他服务的服务，如果有的话返回任何类型的错误（不是200 的状态）然后我需要异步的东西等待而不是继续。

在我看来，我从来没有看到过那么好的例子，因为它非常简单。

我读了很多关于Angular（1）在幕后做什么的文章，我看到有$ q，.then，.success等......

似乎我遇到了返回的问题，并且在没有检查问题的情况下进行了其他嵌套和捆绑服务调用。

基本上这张图片显示了回来的内容

数据：null（不好）
errorList数组

这是我的操作顺序

  this.submitEnrollment = function（enrollment）{
 return getSubmit（requestData）; 
} 
 
 // 
 
以下的哪个CALL变量getSubmit = function（request）{
 return SparkRequestService 
 .submitRequest（request）
 .then（
 function（resData）{
 console.log（resData，resData）; 
 enrollmentService.resetEnrollment（）; 
 return resData; 
}，
函数（resData）{
 console.log（'error'）; 
} 
）; 
} 
  

然后我肯定在调用 SparkRequestService.submitRequest（请求）
但是基于附加的图片，我收到 resData

$中的错误b $ b

所以，似乎我需要查询 resData 吧？那么我真的不应该允许这个其他服务被称为 enrollmentService.resetEnrollment（）;

我怎么能重构停止处理？ if语句在 .then 中？

解决方案

为防止拒绝处理程序转换被拒绝的承诺履行承诺，重要的是使用拒绝处理程序中的 throw 语句：

  var getSubmit = function（请求）{
返回SparkRequestService 
 .submitRequest（请求）
 .then（
 function（resData）{
 console.log（resData，resData）; 
 enrollmentService.resetEnrollment（）; 
返回resData; 
}，
函数（errorResponse）{
 console.log（'error'）; 
 //重要
 //投掷链拒绝
抛出errorResponse; 
} 
）; 
} 
  

当函数省略 return 或抛出语句，该函数返回值 undefined 。这将转换被拒绝的承诺，以履行已解决的价值 undefined 。

---

问题是......这是一个包含在退货对象中的业务错误

要转换对已拒绝承诺的履行承诺，请使用 throw 语句。

  this.submitEnrollment = function（enrollment）{
 var promise = getSubmit（requestData）; 
 var newPromise = promise.then（function（response）{
 if（response.data.hasErrors）{
 console.log（response.data.errorList）; 
 response。 data.errorList.push（submitEnrollent：Rejected）; 
 // THROW创建拒绝
抛出响应; 
} else {
 // RETURN响应链成功
返回响应; 
} 
}）; 
返回newPromise; 
} 
  

当承诺被转换拒绝时，将跳过链中的所有后续成功处理程序。将跟踪链，直到找到拒绝处理程序。

I thought that I had this all figured out on previous projects through the years.. Apparently not.

Goal : Take Service that calls other Services and if there is any type of error being returned ( not a status of 200 ) then I need the async thing to be waiting and not proceeding.

Seems to me like I don't ever see really that great of examples as it is all very simplistic.

I read various articles about what Angular (1) is doing under the hood , and i see that there are $q, .then, .success etc..

Seems that I am having issues with return and with other nested and bundled service calls being made without any checking of a problem.

Essentially this image shows what is coming back

data : null ( that is bad) errorList Array1 0 "This order cannot be submitted... " ( bad too) hasErrors : true ( bad as well)

So that data is important to me to capture and display to user and then NOT move onto more processing

This is my order of operations

this.submitEnrollment = function (enrollment) {
    return getSubmit(requestData);
}

// Which CALLS below

var getSubmit = function (request) {
    return SparkRequestService
        .submitRequest(request)
        .then(
            function (resData) {
                console.log("resData", resData);
                enrollmentService.resetEnrollment();
                return resData;
            }, 
            function (resData) {
                console.log('error');
            }
        );
}

Then I'm certainly calling SparkRequestService.submitRequest(request) but based on the image attached, I am getting the error in the resData

So, it seems that I need to interrogate the resData right? So then I really should NOT ALLOW this other service to be called enrollmentService.resetEnrollment();

How can i refactor to stop from that getting processed? if statement in the .then ?

解决方案

To prevent a rejection handler from converting a rejected promise to a fulfilled promise it is important use a throw statement in the rejection handler:

var getSubmit = function (request) {
    return SparkRequestService
        .submitRequest(request)
        .then(
            function (resData) {
                console.log("resData", resData);
                enrollmentService.resetEnrollment();
                return resData;
            }, 
            function (errorResponse) {
                console.log('error');
                //IMPORTANT
                //throw to chain rejection
                throw errorResponse;
            }
        );
}

When a function omits a return or throw statement, the function returns a value of undefined. This will convert a rejected promise to a fulfilled promise that resolves with a value of undefined.

---

Problem is that ... it is a business error wrapped up in a return object

To convert a fulfilled promise to a rejected promise, use a throw statement.

this.submitEnrollment = function (enrollment) {
    var promise = getSubmit(requestData);
    var newPromise = promise.then(function(response) {
         if (response.data.hasErrors) {
             console.log(response.data.errorList);
             response.data.errorList.push("submitEnrollent: Rejected"); 
             //THROW to create rejection
             throw response;
         } else {
             //RETURN response to chain success
             return response;
         }
    });
    return newPromise;
}

When a promise is converted to a rejection, all subsequent success handlers in the chain will be skipped. The chain will be followed until a rejection handler is found.

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