我需要两个AngularJS $ http服务的实例呢？ [英] I need two instances of AngularJS $http service or what?
问题描述
我想为我的$ http服务添加一个响应拦截器以进行错误处理。拦截器逻辑包括使用$ http发送错误消息到服务器，在必要的情况下，但是，我不想向服务器发送有关错误消息的错误消息，我的意思是，我想要在发送错误时禁用我的拦截器消息到服务器。
I want add a response interceptor to my $http service for error handling purposes. The interceptor logic include send errors messages to server using $http in case necessary, BUT I don't want send errors messages to the server about errors messages, I mean, I want disable my interceptor while sending error message to the server.
我的想法是创建一个名为remote_log的服务，并将其中的所有代码发送到服务器。那个服务当然会使用$ http服务并将其放在依赖列表中。
My idea was create a service named 'remote_log' and put inside it all the code needed to send error to server. That service of course will use the $http service and have it in its dependency list.
然后添加作为拦截器的依赖关系到'remote_log'服务，并使用当需要向服务器发送错误时，拦截器中的'remote_log'。问题是：
Then add as dependency of the interceptor to the 'remote_log' service, and use the 'remote_log' inside the interceptor when need send errors to the server. The problems is that:
当$ http服务仍未实例化/可访问时，拦截器必须使用$ httpProvider定义，因此拦截器代码内不能一个依赖于$ http服务，因为循环依赖错误发生。
Interceptors must be defined using the $httpProvider when the $http service still is not instantiated/accessible, so, inside the interceptor code can't be a dependency to that the $http service because a "Circular dependency" error happen.
我认为我唯一的选择是创建一个单独的$ http服务实例在我的' remote_log，一个不使用我在创建拦截器时设置的$ httpProvider配置的实例。我的问题是：我该怎么做？任何其他想法？
I think my only option is create a separate instance of the $http service inside my 'remote_log', an instance that don't uses the $httpProvider configuration I set while creating the interceptor. My question is: How can I do that? Any other ideas?
推荐答案
1。循环依赖问题。
那么为什么出现错误？以下是对此过程的简要概述：
1. Circular dependency problem.
So, why does the error appear? Here is a quick overview of the process:
- $ http服务被要求。
- $ httpProvider请求构建它。
- 在构建期间，您注册拦截器，请求$ http服务尚未存在。
- 您会收到循环依赖错误
- $http service is requested.
- $httpProvider is asked to construct it.
- During construction you register interceptor, that requests $http service not existing yet.
- You get "Circular dependency" error.
使用angular.injector（）创建您的依赖关系。请注意，您将创建另一个$ http服务，独立于您的应用程序。
Create your dependency using angular.injector(). Notice, that you will create another $http service, independent from your app.
$httpProvider.interceptors.push(function($q) {
$injector = angular.injector();
return {
response: function(response) {
$injector.invoke(function($http) {
// This is the exterior $http service!
// This interceptor will not affect it.
});
}
};
});
在拦截器中注入$注射器，并使用它在$ http初始化之后，在您需要它们时检索依赖关系。这些依赖关系是您的应用程序的注册服务，不会重新创建！
Inject $injector in your interceptor and use it to retrieve dependencies after $http initialization, right at the time you need them. These dependencies are registered services of your app and will not be created anew!
$httpProvider.interceptors.push(function($q, $injector) {
return {
response: function(response) {
$injector.invoke(function($http, someService) {
// $http is already constructed at the time and you may
// use it, just as any other service registered in your
// app module and modules on which app depends on.
});
}
};
});
如果您使用第二个解决方案，实际上有两个问题：
If you use the second solution, there are actually two problems:
- 如果您在
拦截器中使用$ http服务，则可能会导致无限次拦截：您发送
请求，拦截器捕获它，发送另一个，捕获另一个，再次发送
，等等。 - 有时您只希望阻止请求被拦截。
$ http服务的'config'参数只是一个对象。您可以创建一个约定，提供自定义参数并在拦截器中识别它们。
The 'config' parameter of $http service is just an object. You may create a convention, providing custom parameters and recognizing them in your interceptors.
例如，我们将nointercept属性添加到配置中，并尝试重复每个用户请求。这是一个愚蠢的应用程序，但有用的例子来了解行为：
For example, let's add "nointercept" property to config and try duplicate every user request. This is a silly application, but useful example to understand the behavior:
$httpProvider.interceptors.push(function($q, $injector) {
return {
response: function(response) {
if (response.config.nointercept) {
return $q.when(response); // let it pass
} else {
var defer = $q.defer();
$injector.invoke(function($http) {
// This modification prevents interception:
response.config.nointercept = true;
// Reuse modified config and send the same request again:
$http(response.config)
.then(function(resp) { defer.resolve(resp); },
function(resp) { defer.reject(resp); });
});
return defer.promise;
}
}
};
});
在拦截器中进行属性测试时，可能会阻止在控制器和服务中的拦截：
Having the testing for property in interceptor, you may prevent the interception in controllers and services:
app.controller('myController', function($http) {
// The second parameter is actually 'config', see API docs.
// This query will not be duplicated by the interceptor.
$http.get('/foo/bar', {nointercept: true})
.success(function(data) {
// ...
});
});
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