Question

我有这个路由器解析器，用于从Google Firestore检索数据。我正在尝试使用解析器来预先获取数据。当我将调试器放置在resolve函数上时，它将向我显示从服务器检索的数据。但是它永远不会从resolve（）方法返回。谁能帮帮我。

路由模块

const routes: Routes = [
    { path: '', component: HomeComponent},
    { path: 'projects', component: ProjectsComponent, resolve: {projectData: ProjectResolver} },
    { path: 'about', component: AboutComponent}
];

应用程序模块

  providers: [
    ProjectService,
    ProjectResolver
  ],

解析器服务

import { Observable } from 'rxjs';
import { ActivatedRouteSnapshot, RouterStateSnapshot, Resolve } from '@angular/router';
import { Injectable } from '@angular/core';
import { ProjectService } from './project.service';
import { map } from "rxjs/operators";
import { Project } from './project.model';

@Injectable()
export class ProjectResolver implements Resolve<Project[]> {

    constructor(private projectService: ProjectService ) {

    }

    resolve(route: ActivatedRouteSnapshot, router: RouterStateSnapshot) : Observable<Project[]> | any{
        return this.projectService.getProjects().pipe(map(project => {
            return project //Debugger shows fetched data(Array of projects)
        }
        ));
    }
}

项目服务

import { AngularFirestore } from 'angularfire2/firestore';
import { Observable } from "rxjs";
import { Injectable } from "@angular/core";

@Injectable()
export class ProjectService {

    constructor(private db: AngularFirestore) {}

    getProjects(): Observable<any> {
        return this.db.collection('currentProjects').valueChanges();
    }

}

**项目组件（此组件从未由Resolver加载 ）**

import { Component, OnInit, Injectable } from '@angular/core';
import { Project } from './project.model';
import { ActivatedRoute } from '@angular/router';
import { ProjectService } from './project.service';
import { Observable } from 'rxjs';

@Component({
  selector: 'app-projects',
  templateUrl: './projects.component.html',
  styleUrls: ['./projects.component.css']
})

export class ProjectsComponent implements OnInit {

   projects: Project[] = [];

  constructor(private route: ActivatedRoute, private projectService: ProjectService) { 
  }

  ngOnInit() {
      this.route.data.subscribe((data: Project[]) => {
        this.projects = data['projectData'];
      })
  }

}

Answer 1

问题是Angular Firebase Observable（事件流）将永远不会像正常的“ observable”那样完成，因此它永远都无法解决。我使用“ take”运算符修改了Observable，以获取第一项并被迫完成。

this.db.collection('currentProjects').valueChanges().take(1);

更改：

已删除ProjectService
修改后的ProjectResolver
修改后的ProjectComponent

我在下面发布了针对我的问题的解决方案：

项目解析器（正在运行）

export class ProjectResolver implements Resolve<any> {

    constructor(private db: AngularFirestore) {

    }

    resolve(route: ActivatedRouteSnapshot, router: RouterStateSnapshot) : any{

        return Observable.from(this.db.collection('currentProjects').valueChanges()
            .do(data => {  
                return data
            }).take(1))
    }
}

项目组件（正在运行）

export class ProjectsComponent implements OnInit {

  private projects: Project[];

  constructor(private route: ActivatedRoute) {

  }

  ngOnInit() {
    this.route.data.subscribe((data) => {
      this.projects = data['projectData'];
    })
  }
}

Answer 2

获取诸如this.route.snapshot.data之类的数据，而不是this.route.data且无需订阅

ngOnInit() {          
   this.projects = this.route.snapshot.data['projectData'];
}

路由器解析器未呈现组件

2 个答案: