我想用子值检索 firebase 数据库数据

Question

query.once("value") .then(function(snapshot) {
      var childData = snapshot.val().user_name;
      var childData2 = snapshot.val().user_id;
 document.writeln(childData);
 document.writeln("\n");
 document.writeln(childData2);
});

this is the code i used for retrieving firebase database value using parent value what changes should i make in this code for retrieving the parent values using the child value

I would like to retrieve user_name with help of password. And also i want it to be work for other records in the users.

Answer 1

If the password is "2110" you can retrieve the user with:

var passwordToLookFor = "2110";
var ref = firebase.database().ref("users");
var query = ref.orderByChild("password").equalTo(passwordToLookFor);
query.once(function(snapshot) {
  snapshot.forEach(function(child) { // loop over the results
    console.log(child.key);
    console.log(child.val().user_name);
  });
});

As Doug commented, please take a moment to read the Firebase documentation on ordering and querying , as it will save you many questions going forward.