AngularJS - AUTO module and $injector

StackOverflow https://stackoverflow.com/questions/21633506

Question

On this page, the Angular docs describe the AUTO module as:

Implicit module which gets automatically added to each $injector.

Yet, the $injector is located inside this AUTO module.

AUTO
    $injector
        AUTO
            $injector ...

Clearly I'm missing something.

How does the AUTO module relate to the angular.module(), and where does the $injector fit in? 

angular.module()
    AUTO
        $injector

This would make sense, but then the docs that imply that AUTO is added to $injector doesn't make sense. I'm wondering if I'm misinterpreting something. So my question is, am I misinterpreting something?

Was it helpful?

Solution

AUTO basically wires up modules with $provide and $injector. The $injector references itself so $injector === $injector.get('$injector'). It avoids the chicken/egg scenario by building up the module outside of the Angular context and manually shoving the $injector and $provide into it. From that point forward the module can then use $provide, $injector, etc. You will never reference a module explicitly called "AUTO" but any module you create via angular.module will have an $injector and $provide. The other services come from the 'ng' module but the AUTO portion of it has to be built up so there is a DI container to use.

OTHER TIPS

There are two injectors, an internal one, and an external one:

The instanceInjector stores the list of instantiated services in the system. It is initialized with an empty object. The providerInjector maintains the list of uninstantiated services.

The angular.injector method can create an instance:

angular.injector().get("$injector")

The built-in module ng can also:

angular.module("ng")._configBlocks[0][0]

References

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