CODEWITHSUNDEEP
angularangular5ngoninit
WestMD
WestMD

Reputation: 71

Angular5: ngOnInit is only invoked once on routing

I have this basic app where I grab data from a firestore with a data service. I have several pages(components), teams, players, statistics...

for instance my team component:

import { Component, OnInit } from '@angular/core';
import { TeamsService } from '../../services/teams.service';
import { Team } from '../../models/team';
import {Observable} from 'rxjs/Observable';


@Component({
  selector: 'app-teams',
  templateUrl: './teams.component.html',
  styleUrls: ['./teams.component.css']
})
export class TeamsComponent implements OnInit {


  public teams: Team[];
  editState: boolean = false;
  teamToEdit: Team;
  showAdd: boolean = false;
  showSelect: boolean = false;
  selectedTeam: Observable<Team>;

  constructor(public teamsService: TeamsService) {
  }

  ngOnInit() {

          this.teamsService.getTeams().subscribe(teams => {
            this.teams = teams;
            console.log('ngOnInit invoked');
          });
        }


  deleteTeam(event, team) {
    const response = confirm('are you sure you want to delete?');
    if (response) {
      this.teamsService.deleteTeam(team);
    }
    return;
  }

  editTeam(event, team) {
    this.editState = !this.editState;
    this.teamToEdit = team;
  }

  updateTeam(team) {
    this.teamsService.updateTeam(team);
    this.teamToEdit = null;
    this.editState = false;
  }

  showAddForm() {
      this.showAdd = !this.showAdd;
    }

  getTeam(event, team) {
    this.showSelect = !this.showSelect;
    this.selectedTeam = this.teamsService.getTeamById(team.id);
  }
}

In the ngOnInit I load my data into the local variables, but once i navigate away to another page and then come back the data is gone. I literally need to refresh the page to reload the data.

How should I solve this?

Upvotes: 1

Views: 1094

Answers (1)

Yakov Fain
Yakov Fain

Reputation: 12378

Create a resolver guard and use it in your route configuration for TeamsComponent. Also, create a service that will do the data retrieval and inject it into the resolver. This service can either make a new request for data each time the user navigates to this route or cache the data and provide them to your TeamComponent on each subsequent visit of the route.

Take a look at this sample app that illustrates the general use of the resolver guard: https://github.com/Farata/angulartypescript/tree/master/code-samples/chapter4/router-advanced-samples/src/app/resolver.

But if you want to implement an injectable service with cache, take a look at the code in data.resolver2.ts and data.service.ts.

Upvotes: 1

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