Question

我正在尝试使用以下

创建@ngrx / store操作

import { ActionReducer, Action } from '@ngrx/store'
import { StoreService } from 'ng2-storeservice'
import { IPatient, Patient } from './patient.service'

export class PatientActions {
  static ADD = '[Patient] ADD';
  static REMOVE = '[Patient] REMOVE';
  static RESET = '[Patient] RESET';

  constructor( public store: StoreService ) { }

  add( path: string, payload: IPatient ) {
    this.store.dispatch( PatientActions.ADD, payload );
  }

  remove( path: string, payload: IPatient ) {
    this.store.dispatch( PatientActions.REMOVE, payload )
  }

  reset( path: string, payload: IPatient ) {
    this.store.dispatch( PatientActions.RESET, payload )
  }
}

export const patient: ActionReducer<IPatient> = (
    state: IPatient = new Patient(), action: Action ) => {
  switch ( action.type ) {
    case PatientActions.ADD:
      return Object.assign( state, action.payload );

    case PatientActions.REMOVE:
      return Object.assign( {}, state, action.payload );

    case PatientActions.RESET:
      return Object.assign( {}, state, action.payload );

    default:
      return state;
  }
};

服务被适当地放置在可识别的模块中。运行应用程序会出现以下错误

metadata_resolver.js:499Uncaught Error: Can't resolve all parameters for PatientActions: (?).
    at CompileMetadataResolver.getDependenciesMetadata (http://localhost:4200/main.bundle.js:31019:19)
    at CompileMetadataResolver.getTypeMetadata (http://localhost:4200/main.bundle.js:30920:26)
    at http://localhost:4200/main.bundle.js:31063:41
    at Array.forEach (native)
    at CompileMetadataResolver.getProvidersMetadata (http://localhost:4200/main.bundle.js:31043:19)
    at http://localhost:4200/main.bundle.js:30741:71
    at Array.forEach (native)
    at CompileMetadataResolver.getNgModuleMetadata (http://localhost:4200/main.bundle.js:30732:44)
    at http://localhost:4200/main.bundle.js:30745:50
    at Array.forEach (native)

感谢任何帮助。

Answer 1

您需要在@Injectable课程中添加PatientsAction装饰器。这就是Angular如何向类中添加元数据。没有元数据，Angular将不知道如何/注入什么。

另见：

When do we need to use @Injectable on our services in Angular2?

无法解析ngrx / store Action的所有参数

1 个答案: