问题描述
我正在尝试在Angular 6应用中实现延迟加载，我所有的http调用都在FeatureModule中进行(延迟加载)，但是我仍然必须在AppModule中添加HttpClientModule而不是在FeatureModule.真的不明白为什么.另外，当我在FeatureModule中添加拦截器时，它们没有拦截任何请求.我只需要在AppModule中添加它(我想是因为HttpClientModule在AppModule中).
I am trying to implement lazy loading in my Angular 6 app, all of my http calls are made in the FeatureModule (lazy loaded), but still I have to add HttpClientModule in my AppModule and not in FeatureModule. Didn't really understand why.Also, when I added interceptors in my FeatureModule, they didn't intercept any request. I have to add it in the AppModule only (I guess, it is because HttpClientModule is in AppModule).
我想了解为什么会这样吗?为什么我们不能只在FeatureModule中有HttpClientModule和HTTP_INTERCEPTORS而在没有进行任何http调用的AppModule中没有?
I want to understand why this is the case?? Why can't we have HttpClientModule and HTTP_INTERCEPTORS only in the FeatureModule and not in AppModule where I am not making any http calls?
推荐答案
要回答此问题.
仅一次在根级别添加HttpClientModule.没有其他模块，无论它们如何从lazy或eager导入，即使它们是从库中导入的也是如此.确保它没有导入HttpClientModule
Only add HttpClientModule at once place at the root level. No other modules regardless of how they are imported lazy or eager even if it is from a library. Ensure that it is not importing HttpClientModule
但是，您可以跨模块使用HTTP_INTERCEPTORS提供程序，而不会出现问题.
You can however use HTTP_INTERCEPTORS providers across modules without an issue.
在跨模块导入HttpClientModule并将其重新导入到另一个模块时，它将有效地重置该模块的HTTP_INTERCEPTORS提供程序.这是预期的行为.如果您需要有关讨论的更多信息，可以查看: https://github.com/angular/angular/issues/20575
When you import HttpClientModule across modules and then re import that into another module it effectively resets the providers for HTTP_INTERCEPTORS for that module.This is an intended behaviour. If you need more information about the discussion you can check: https://github.com/angular/angular/issues/20575
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