Remove property in Realm object

Question

I'm trying to remove a property in one of my Realm objects however I'm not sure how to write a migration for this.

I just removed the property from my object's header file but that didn't work as I get this error:

Terminating app due to uncaught exception 'RLMException', reason: 'Migration is required for object type 'Stock' due to the following errors: - Property 'percentageOn' is missing from latest object model.'

I know how to write a migration add fields, but how do I remove one?

Of course you are not able to do it directly without the consequence. Solution 1: Remove the property like U did and remove the app from the simulator. This solves the issue with DB inconsistency. Solution 2: Your app is in production and users already use it. So U need to perform the migration to not to affect your customers. And please read the doc what to do in such case: realm.io/docs/objc/latest/#migrations — David

TiM TiM · Accepted Answer · 2015-06-09T13:28:48

What David said is correct. If you make sure to perform a migration properly, then Realm can easily handle properties that have been removed as well as added. Unless you actually still need the value in percentageOn, you can even leave the migration block empty like in the example on the Realm website:

// Inside your [AppDelegate didFinishLaunchingWithOptions:]

// Notice setSchemaVersion is set to 1, this is always set manually. It must be
// higher than the previous version (oldSchemaVersion) or an RLMException is thrown
[RLMRealm setSchemaVersion:1
            forRealmAtPath:[RLMRealm defaultRealmPath] 
        withMigrationBlock:^(RLMMigration *migration, NSUInteger oldSchemaVersion) {
  // We haven’t migrated anything yet, so oldSchemaVersion == 0
  if (oldSchemaVersion < 1) {
    // Nothing to do!
    // Realm will automatically detect new properties and removed properties
    // And will update the schema on disk automatically
  }
}];

// now that we have called `setSchemaVersion:withMigrationBlock:`, opening an outdated
// Realm will automatically perform the migration and opening the Realm will succeed
[RLMRealm defaultRealm];

Remove property in Realm object

1 Answers