[Question] data will not reload after page routing using Firestore.

Hi there,

I am new here, could you please help me to check how to reload the data after page routing and keep the Firestore data source in the ng2-smart-table?

my Firestore service :
`import { Injectable } from '@angular/core';

import { AngularFirestore, AngularFirestoreCollection, AngularFirestoreDocument } from '@angular/fire/firestore';

import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

export interface student {
id?: string;
status: string;
action: string;
name: string;
}

@Injectable({
providedIn: 'root'
})
export class FirestoreService {

studentsCollection: AngularFirestoreCollection;

public students: Observable;

constructor(private afs: AngularFirestore) {
this.studentsCollection = this.afs.collection('students');
this.students = this.studentsCollection.snapshotChanges().pipe(
map((actions) => {
return actions.map((a) => {
const data = a.payload.doc.data();
return { id: a.payload.doc.id, ...data };
});
})
);
}

getData(){
// ['added', 'modified', 'removed']
return this.students;
}
}
`

and ng2-smart-table:
`import { Component,OnInit } from '@angular/core';
import { LocalDataSource } from 'ng2-smart-table';

import { SmartTableService } from '../../../@core/data/smart-table.service';
import { FirestoreService, student } from '../../../@core/data/firestore.service';

@Component({
selector: 'ngx-smart-table',
templateUrl: './smart-table.component.html',
styles: [`
nb-card {
transform: translate3d(0, 0, 0);
}
`],
})
export class SmartTableComponent implements OnInit{
students: student[];
student: student = {
status: "status",
action: "action",
name: "name",
}
settings = {
add: {
addButtonContent: '',
createButtonContent: '',
cancelButtonContent: '',
},
edit: {
editButtonContent: '',
saveButtonContent: '',
cancelButtonContent: '',
},
delete: {
deleteButtonContent: '',
confirmDelete: true,
},
columns: {
id: {
title: 'ID',
type: 'number',
},
firstName: {
title: 'First Name',
type: 'string',
},
lastName: {
title: 'Last Name',
type: 'string',
},
username: {
title: 'Username',
type: 'string',
},
email: {
title: 'E-mail',
type: 'string',
},
age: {
title: 'Age',
type: 'number',
},
},
};

source: LocalDataSource;

constructor(private service: SmartTableService, private fs:FirestoreService) {
//const data = this.service.getData();
//this.source.load(data);
}

ngOnInit() {

this.fs.getData().subscribe(res => {
this.source = new LocalDataSource(res);
});
}

add() {
this.fs.createStudent(this.student);
}

onDeleteConfirm(event): void {
if (window.confirm('Are you sure you want to delete?')) {
event.confirm.resolve();
} else {
event.confirm.reject();
}
}
}
`

the ng2-smart-table will load the data from Firestore in first time, and after I switch to other page and back ng2-smart-table again the data were disappear.

BR,
Iron.Huang