node.js Nodejs 抛出异常
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Nodejs throw exception
提问by Muhamet Aljobairi
I'm working on Nodejs service-side application, my case is that i want to return the throw an exception to the caller(who did call the function), i did two cases, one outside the callback, and the another inside the callback, also the parent has try catch blocks.
我正在研究 Nodejs 服务端应用程序，我的情况是我想将抛出异常返回给调用者（谁调用了函数），我做了两种情况，一种在回调之外，另一种在回调内，父级也有 try catch 块。
concept : throw(Business function)-->throw (Business function) -->try & catch
概念：throw(业务函数)-->throw(业务函数)-->try & catch
Outside the callback is working correctly. Inside the callback didn't return the exception to the parent.
外部回调工作正常。在回调内部没有将异常返回给父级。
I want to to this scenario,because I'm looking to throw an exception to the parent and stop completion the functions, and this's exist in Java, C++, C and .NET.
我想要这种情况，因为我希望向父级抛出异常并停止完成函数，这在 Java、C++、C 和 .NET 中存在。
So why this scenario is not working with me ?!
那么为什么这个场景对我不起作用？！
My example here with 2 different cases :
我这里的例子有两种不同的情况：
FactoryController.prototype.create = function (callback) {
//The throw is working, and the exception is returned.
throw new Error('An error occurred'); //outside callback
try {
this.check(function (check_result) {
callback(check_result);
});
} catch (ex) {
throw new Error(ex.toString());
}
}
FactoryController.prototype.create = function (callback) {
try {
this.check(function (check_result) {
//The throw is not working on this case to return the exception to the caller(parent)
throw new Error('An error occurred'); //inside callback
});
} catch (ex) {
throw new Error(ex.toString());
}
}
采纳答案by Tapirboy
Exceptions occurs because you are throwing the errors. If you rather want to return the error to the caller, you need to provide it in the callback. Add the error as parameter to the callback.
发生异常是因为您抛出错误。如果您希望将错误返回给调用者，则需要在回调中提供它。将错误作为参数添加到回调中。
Usually the callback pattern is callback(error, result);
通常回调模式是 callback(error, result);
callback(new Error(ex.toString())); // ignore result param
回答by Chamath Nanayakkara
would the below code satisfy your requirement
下面的代码是否满足您的要求
'use strict';
var inherits =require('util').inherits;
//Parent
function factoryController(n){
this.name=n;
}
//parent prototype function
factoryController.prototype.create = function (type) {
var retVal="";
try {
throw new Error('An error occurred');
retVal=this.name+' is a '+ type;
}
catch(e){
retVal=e.toString();
}
return retVal;
}
function subsidaryController(name) {
// Call parent constructor
factoryController.call(this, name);
}
inherits(subsidaryController,factoryController);
// Additional member functions
subsidaryController.prototype.fn = function (locations) {
var retVal="";
try {
throw new Error('Another error occurred');
retVal='Having branches in' + locations;
}
catch(e){
retVal=e.toString();
}
return retVal;
}
let fc = new subsidaryController('ABC Factory');
console.log(fc.create('Manufacturer' ));
console.log(fc.fn('Europe and Asia'));
