Not able to invoke subscribe function 2nd times

Ionic Framework
1

Dear All,

I am facing issues while calling subscribe function first time its calling and getting records but second time when I back to the same page then I am not getting any data.

Step 1: Created Service (urx.service.ts)

private userTrxCollection: AngularFirestoreCollection;
private userTrxs: Observable<UserTrx>;
constructor(public db: AngularFirestore) {
this.userTrxCollection = db.collection(‘userTrxs’);
this.userTrxs = this.userTrxCollection.snapshotChanges().pipe(
map(actions => {
return actions.map(a => {
const data = a.payload.doc.data();
const id = a.payload.doc.id;
return { id, …data };
});
})
);
}

Step 2: created one page and import this service (urx.page.ts)

ngOnInit() {

this.TrxID=this.route.snapshot.params['refTrxId'];
if(this.TrxID){
  this.loadUserTrx();
}

async loadUserTrx() {
const loading = await this.loadingController.create({
message: ’ ’

});

await loading.present();
this.userCashTrx.getUserTrxs().subscribe(ucash=>{
loading.dismiss();
this.userTrxs = ucash;
console.log(this.userTrx);
this.userTrxs = this.userTrxs.filter(res=> res.userEmail == this.userEmail)
for(let tx of this.userTrxs){
this.total_Trx = this.total_Trx + tx.cost;
}
this.total_Trx=Math.round(this.total_Trx * 100) / 100;
console.log(this.total_Trx);
this.total_Trx_Balance = this.total_WalletAmt - this.total_Trx;
});

}

Login the page and got all the data so far its fine now i cam back to this page from another one this subscribe function not working for me.

Please help me out.

I have tried ngDestroy function to unsubscribe collection but no luck.

Your help would be appreciated

please let me know if you need more clarity of the above.

Thanks

Mozib

2

Thanks for this information. It is very useful