How do I prevent data duplication for Firebase Realtime Database, Web, JavaScript [duplicate]

Question

This is my database structure for the Users.

This is my database structure

As you can see in the picture, there are 2 same Identification number are registered successfully.

How can I prevent the "ICNumber"(Identification Number) to be registered more than once?

This is the rule in my RealTime Database:

This is the rule in my RealTime Database

I tried putting this piece of code but it doesn't seem to work. Is there any way I can do the prevention in my Javascript or any correct way in my Firebase Rule?

There is no reliable way to prevent duplicate values in a JSON structure like the one you have now. It would require that the security rules scan across all nodes, which just doesn't scale. The only way to ensure something is unique in Firebase, is to use those values as the keys in the JSON. See stackoverflow.com/q/25294478, stackoverflow.com/a/57616541, stackoverflow.com/a/41113997, and stackoverflow.com/a/46056547 — Frank van Puffelen
– Frank van Puffelen, Commented Mar 30, 2020 at 14:57
Understood. The links does helps a lot! Thanks ! @FrankvanPuffelen — Dreammmm
– Dreammmm, Commented Mar 31, 2020 at 7:29

Peter Haddad · Accepted Answer · 2020-03-30 11:39:16Z

1

In your code, you can do the following:

// Get a reference to the database service
var database = firebase.database();
var dataRetrieved = database.ref('users').child(userId).orderByChild("ICNumber").equalTo("000326141809");
dataRetrieved.on('value', function(snapshot) {
  if(snapshot.exists()){
     // do the required
   }
});

You can use a query to check if you have an ICNumber equal to 000326141809 and then use the method exists() to check if it is already in the database

answered Mar 30, 2020 at 11:39

Peter Haddad

81.2k26 gold badges148 silver badges149 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Dreammmm Over a year ago

Thank you so much! Your code works, it detects whether or not the value is already in the database. However, the code still runs my signup() function. Do you have any workaround for this? I've tried: break, return, and preventDefault statements, but they don't seem to work

Peter Haddad Over a year ago

Just write the signup inside the else and use once instead of on

Dreammmm Over a year ago

Aight man understood! Thanks for the help!

Collectives™ on Stack Overflow

How do I prevent data duplication for Firebase Realtime Database, Web, JavaScript [duplicate]

1 Answer 1

3 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Linked

Related