ReflectiveInjector

A ReflectiveDependency injection container used for instantiating objects and resolving dependencies.

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Deprecated: from v5 - slow and brings in a lot of code, Use Injector.create instead.

abstract class ReflectiveInjector implements Injector {
  static resolve(providers: Provider[]): ResolvedReflectiveProvider[]
  static resolveAndCreate(providers: Provider[], parent?: Injector): ReflectiveInjector
  static fromResolvedProviders(providers: ResolvedReflectiveProvider[], parent?: Injector): ReflectiveInjector
  abstract parent: Injector | null
  abstract resolveAndCreateChild(providers: Provider[]): ReflectiveInjector
  abstract createChildFromResolved(providers: ResolvedReflectiveProvider[]): ReflectiveInjector
  abstract resolveAndInstantiate(provider: Provider): any
  abstract instantiateResolved(provider: ResolvedReflectiveProvider): any
  abstract get(token: any, notFoundValue?: any): any
}

Description

An Injector is a replacement for a new operator, which can automatically resolve the constructor dependencies.

In typical use, application code asks for the dependencies in the constructor and they are resolved by the Injector.

Static methods

@Injectable()
class Engine {
}

@Injectable()
class Car {
  constructor(public engine:Engine) {}
}

var providers = ReflectiveInjector.resolve([Car, [[Engine]]]);

expect(providers.length).toEqual(2);

expect(providers[0] instanceof ResolvedReflectiveProvider).toBe(true);
expect(providers[0].key.displayName).toBe("Car");
expect(providers[0].dependencies.length).toEqual(1);
expect(providers[0].factory).toBeDefined();

expect(providers[1].key.displayName).toBe("Engine");
});

@Injectable()
class Engine {
}

@Injectable()
class Car {
  constructor(public engine:Engine) {}
}

var injector = ReflectiveInjector.resolveAndCreate([Car, Engine]);
expect(injector.get(Car) instanceof Car).toBe(true);

@Injectable()
class Engine {
}

@Injectable()
class Car {
  constructor(public engine:Engine) {}
}

var providers = ReflectiveInjector.resolve([Car, Engine]);
var injector = ReflectiveInjector.fromResolvedProviders(providers);
expect(injector.get(Car) instanceof Car).toBe(true);

Properties

Methods

class ParentProvider {}
class ChildProvider {}

var parent = ReflectiveInjector.resolveAndCreate([ParentProvider]);
var child = parent.resolveAndCreateChild([ChildProvider]);

expect(child.get(ParentProvider) instanceof ParentProvider).toBe(true);
expect(child.get(ChildProvider) instanceof ChildProvider).toBe(true);
expect(child.get(ParentProvider)).toBe(parent.get(ParentProvider));

class ParentProvider {}
class ChildProvider {}

var parentProviders = ReflectiveInjector.resolve([ParentProvider]);
var childProviders = ReflectiveInjector.resolve([ChildProvider]);

var parent = ReflectiveInjector.fromResolvedProviders(parentProviders);
var child = parent.createChildFromResolved(childProviders);

expect(child.get(ParentProvider) instanceof ParentProvider).toBe(true);
expect(child.get(ChildProvider) instanceof ChildProvider).toBe(true);
expect(child.get(ParentProvider)).toBe(parent.get(ParentProvider));

@Injectable()
class Engine {
}

@Injectable()
class Car {
  constructor(public engine:Engine) {}
}

var injector = ReflectiveInjector.resolveAndCreate([Engine]);

var car = injector.resolveAndInstantiate(Car);
expect(car.engine).toBe(injector.get(Engine));
expect(car).not.toBe(injector.resolveAndInstantiate(Car));

@Injectable()
class Engine {
}

@Injectable()
class Car {
  constructor(public engine:Engine) {}
}

var injector = ReflectiveInjector.resolveAndCreate([Engine]);
var carProvider = ReflectiveInjector.resolve([Car])[0];
var car = injector.instantiateResolved(carProvider);
expect(car.engine).toBe(injector.get(Engine));
expect(car).not.toBe(injector.instantiateResolved(carProvider));

Usage notes

Example

The following example creates an Injector configured to create Engine and Car.

@Injectable()
class Engine {
}

@Injectable()
class Car {
  constructor(public engine:Engine) {}
}

var injector = ReflectiveInjector.resolveAndCreate([Car, Engine]);
var car = injector.get(Car);
expect(car instanceof Car).toBe(true);
expect(car.engine instanceof Engine).toBe(true);

Notice, we don't use the new operator because we explicitly want to have the Injector resolve all of the object's dependencies automatically.