CODEWITHSUNDEEP
javascriptfirebase
Chor Sipahi
Chor Sipahi

Reputation: 546

How to check if a node(child) with multiple fields exist in Firebase?

This shows a way to check if a node with a given id exists or not. However, I am inserting a node using push method with random ids. Suppose nodes have fields A, B and C. Before inserting a node with A = a1, B = b1, C = c1. I want to check if a node with this combination exists or not.

Upvotes: 4

Views: 502

Answers (2)

Chor Sipahi
Chor Sipahi

Reputation: 546

As written in David's answer we can read and check. However he didn't mention about when we wanna check for multiple child nodes. forEach method is what will help in such case. So we can apply David's solution for each chlid using forEach.

Upvotes: 1

David East
David East

Reputation: 32604

You can always do a read and check the properties:

function checkData(data) {
  return data.A === 'a1' && data.B === 'b1' && data.C === 'c1';
}
var ref = new Firebase('<my-firebase-app>/item');
ref.once('value', function(snap) {
  var hasCombination = checkData(snap.val());
});

But you can also write your security rules so that that combination only ever exists. Using Bolt, the Security Rules compiler, makes this even easier, because Bolt allows you to map types to paths.

type Data {
  a: String;
  b: String;
  c: String;
}

path /data is Data;

This code generates a set of validation rules that make sure that objects that only have String properties of A, B, and C are saved to the /data path.

Upvotes: 1

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