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API > @angular/core

SkipSelf

A constructor parameter decorator that tells the DI framework that dependency resolution should start from the parent injector.

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说明

In the following example, the dependency can be resolved when instantiating a child, but not when instantiating the class itself.

class Dependency {} @Injectable() class NeedsDependency { constructor(@SkipSelf() public dependency: Dependency) { this.dependency = dependency; } } const parent = ReflectiveInjector.resolveAndCreate([Dependency]); const child = parent.resolveAndCreateChild([NeedsDependency]); expect(child.get(NeedsDependency).dependency instanceof Dependency).toBe(true); const inj = ReflectiveInjector.resolveAndCreate([Dependency, NeedsDependency]); expect(() => inj.get(NeedsDependency)).toThrowError();
      
      
  1. class Dependency {}
  2.  
  3. @Injectable()
  4. class NeedsDependency {
  5.   constructor(@SkipSelf() public dependency: Dependency) { this.dependency = dependency; }
  6. }
  7.  
  8. const parent = ReflectiveInjector.resolveAndCreate([Dependency]);
  9. const child = parent.resolveAndCreateChild([NeedsDependency]);
  10. expect(child.get(NeedsDependency).dependency instanceof Dependency).toBe(true);
  11.  
  12. const inj = ReflectiveInjector.resolveAndCreate([Dependency, NeedsDependency]);
  13. expect(() => inj.get(NeedsDependency)).toThrowError();

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