如何使用Firebase和Ionic 3以HTML显示数据

Question

I want to display a data from database from Firebase, but it's not working. I'm using Ionic 3

Code on my TypeScript file.

let questionRef= firebase.database().ref().child("Test");
  questionRef.on('value', function(snapshot){
    let question = snapshot.val();
  });

HTLM

<h4 style="text-align:center;">{{question}}</h4>

I tryied to do an alert to show the question and it worked, but the display inside the h4 is not working.

Answer 1

You need to declare question globally and also use fat arrow function as shown below.

.ts

question:string="";

constructor(){

let questionRef= firebase.database().ref().child("Test");
  questionRef.on('value', (snapshot)=>{
    this.question = snapshot.val();
  });

}

.html

<h4 style="text-align:center;">{{question}}</h4>