通过开发一个angular 5应用程序,我意识到我正在重复创建通过REST api访问模型的服务,所以我认为将它们抽象到以下工厂是有意义的:
import { Inject } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { action, observable } from 'mobx-angular';
import { ObservableArray } from 'mobx/lib/types/observablearray';
interface Parameters {
baseUrl: string;
name: string;
}
export interface BaseModel {
_id: string;
}
export interface RestCollectionServiceType<T> {
items: ObservableArray<T>;
get: () => Promise<void>;
create: (T) => Promise<void>;
remove: (T) => Promise<void>;
update: (T) => Promise<void>;
}
export default <T extends BaseModel>({ baseUrl, name }: Parameters) => {
class RestCollectionService {
@observable
items;
constructor(@Inject(HttpClient) private http: HttpClient) {
this.items = [];
}
@action
async get() {
const items = await this.http.get<T[]>(baseUrl)
.toPromise();
this.items.clear();
this.items.push(...items);
}
// ...
// Rest of the actions
// ...
}
return RestCollectionService;
};
然后一个示例服务如下:
import restCollectionServiceFactory, { RestCollectionServiceType, BaseModel } from '../utils/restCollectionServiceFactory';
export interface Team extends BaseModel {
name: string;
}
export interface TeamsService extends RestCollectionServiceType<Team> {
}
export const TeamsService = restCollectionServiceFactory<Team>({
baseUrl: '/api/teams',
name: 'Team',
});
在开始的时候,我在DI中苦苦挣扎,因为装饰器只能在类指令之前使用,所以我无法使我的任何服务(例如TeamsService)可注射但是通过使用RestCollectionServiceType构造函数中的Inject装饰器来解决,因为服务没有其他依赖来解决它应该保存不要使它们注入,只是将它们添加到模块的providers数组中应该足够我所理解的
...
import { TeamsService } from './services/teams.service';
...
@NgModule({
declarations: [
...
],
imports: [
...
],
providers: [
...
TeamsService,
...
],
bootstrap: [
AppComponent,
],
})
export class AppModule { }
问题是这与ng服务正常,但是当我尝试构建时,我得到以下错误:ERROR in : Can't resolve all parameters for TeamsAdminPageComponent in .../src/app/pages/admin/teams/teamsAdmin.page.ts: (?).
是teamsAdmin.pate.ts唯一依赖于TeamsService的组件
import {Component, Inject, OnInit} from '@angular/core';
import { TeamsService } from '../../../services/teams.service';
@Component({
selector: 'rm-admin-teams',
templateUrl: './teamsAdmin.page.html',
})
export class TeamsAdminPageComponent implements OnInit {
columns = ['name', 'countryCode'];
create = (team) => this.teamsService.create(team);
remove = (team) => this.teamsService.remove(team);
update = (team) => this.teamsService.update(team);
constructor(@Inject(TeamsService) private teamsService: TeamsService) { }
ngOnInit(): void {
this.teamsService.get();
}
}
怎么能解决这个问题?提前致谢。
您的TeamsService
可能需要是一个类而不是接口,因此注入器可以创建它的实例。您还需要使用@Injectable()
注释服务,否则注入器将抛出:
@Injectable()
export class TeamsService extends RestCollectionServiceType<Team> {
}