Angular Promises 和 Chaining:如果链有业务数据错误，如何中断链 [英] Angular Promises and Chaining: How to break a chain if it has business data errors

问题描述

我以为这些年来我已经在以前的项目中弄清楚了这一切......显然没有.

目标:获取调用其他服务的服务，如果返回任何类型的错误(不是 200 状态)，那么我需要异步事情等待而不是继续.

在我看来，我从来没有见过这么棒的例子，因为它们都非常简单.

我阅读了各种关于 Angular (1) 在幕后做了什么的文章，我看到有 $q、.then、.success 等.

似乎我在 return 和其他嵌套和捆绑的服务调用方面遇到了问题，而没有对问题进行任何检查.

基本上这张图片显示的是什么回来了

data : null(不好)errorList Array

这是我的操作顺序

this.submitEnrollment = 函数(注册){返回 getSubmit(requestData);}//下面调用var getSubmit = 函数(请求){返回 SparkRequestService.submitRequest(请求).然后(函数(resData){console.log("resData", resData);注册服务.resetEnrollment();返回 resData;},函数(resData){console.log('错误');});}

那我当然是在调用 SparkRequestService.submitRequest(request)但根据附加的图像，我在 resData

中收到错误

那么，看来我需要询问 resData 对吗?那么我真的不应该允许这个其他服务被称为 enrollmentService.resetEnrollment();

我如何重构以停止处理?.then 中的 if 语句?

解决方案

为了防止拒绝处理程序将被拒绝的承诺转换为已履行的承诺，使用 throw 拒绝处理程序中的语句:

var getSubmit = 函数(请求){返回 SparkRequestService.submitRequest(请求).然后(函数(resData){console.log("resData", resData);注册服务.resetEnrollment();返回 resData;},功能(错误响应){console.log('错误');//重要的//抛出链式拒绝抛出错误响应；});}

当函数省略return 或throw 语句时，函数返回undefined 的值.这将转换一个被拒绝的承诺为一个已履行的承诺，该承诺以undefined的值解析.

<小时><块引用>

问题是......这是一个包含在返回对象中的业务错误

要将已履行的承诺转换为被拒绝的承诺，请使用 throw 语句.

this.submitEnrollment = 函数(注册){var promise = getSubmit(requestData);var newPromise = promise.then(function(response) {如果(response.data.hasErrors){console.log(response.data.errorList);response.data.errorList.push("submitEnrollent: Rejected");//THROW 创建拒绝抛出响应；} 别的 {//返回链成功的响应返回响应；}});返回新承诺；}

当承诺转换为拒绝时，链中的所有后续成功处理程序都将被跳过.将遵循该链，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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