我创建了 CRUD 任务的通用服务，该服务通过 DI（依赖注入）使用 HttpClient，但我需要在服务的构造函数中通知另一个值，如何实现？
因为当我在类的构造函数中定义将使用 DI 使用 CRUD 服务时，无法将参数传递给构造函数
下面是服务
import { Injectable } from "@angular/core";
import { HttpClient } from "@angular/common/http";
import { CrudInterface } from "@app/core/crud.interface";
import { environment } from "@env/environment";
import { Observable } from "rxjs/Observable";
@Injectable()
export class CRUD<T> implements CrudInterface<T>{
endpoint: string;
constructor(private http: HttpClient, routeDir: string){
this.endpoint = `${environment.endpoint}/${routeDir}`;
}
getAll(): Observable<T[]> {
return this.http.get<T[]>(`${this.endpoint}`);
}
get(id: number): Observable<T> {
return this.http.get<T>(`${this.endpoint}/${id}`);
}
create(object: T): Observable<T> {
return this.http.post<T>(`${this.endpoint}`, object);
}
update(object: T): Observable<T> {
return this.http.put<T>(`${this.endpoint}`, object);
}
delete(id: number): Observable<any> {
return this.http.delete<T>(`${this.endpoint}/${id}`);
}
}
import { Usuario } from "@app/usuarios/model/usuario";
import { CRUD } from "@app/core/crud.service";
class TestCrudServide {
constructor(
/**
* How to inform the parameter here?
* in this case the endpoint (2nd parameter of the CRUD service)
*/
private crudService: CRUD<Usuario>
){ }
getAll(){
this.crudService.getAll();
}
}
UPDATE
利用 Sannon Aragão（感谢）提出的工厂概念解决方案，我创建了用于动态创建实例的服务提供者
https://angular.io/guide/dependency-injection#factory-providers https://angular.io/guide/dependency-injection#factory-providers
export class crudServiceProvider {
static getProvider(routeDir: string) {
return {
provide: CRUD,
deps: [HttpClient],
useFactory: (dep) => {
return new CRUD(dep, routeDir);
}
}
}
}
在我的组件中
@Component({
selector: 'app-revenda',
templateUrl: './revenda.component.html',
styleUrls: ['./revenda.component.css'],
providers:[ crudServiceProvider.getProvider('/api/revenda') ]
})
export class RevendaComponent implements OnInit {
constructor(
private crudService: CRUD<Revenda>
) { }
ngOnInit() {
// now it's work with the correct path and type!
this.crudService.get(1).subscribe(item => console.log(item));
}
}
Filipe，来自您想要提供服务的模块：
{
provide: 'userService1',
deps: [ HttpClient ],
useFactory: (dep1 ) => {
return new UserService( dep1, 'test');
}
}
在您将使用该服务的组件中：
constructor( @Inject('userService1') private userService: UserService ) { }
在 CRUD API 中，您可以获取字符串形式的参数：
constructor( private http: HttpClient, private s: string) {
console.log(s); // will print 'test'
}
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