CRUD - Delete - React Native SDK

Delete an Object

To delete an object from a realm, pass the object to Realm.delete() inside of a write transaction.

In the following example of a DogList component, we:

1. Get access to the opened realm instance by calling the useRealm() hook.

2. Retrieve all dogs in the realm instance by passing Dog to the useQuery() hook.

3. Create a component method deleteDog() that takes in a Dog object as a parameter. Within the method, we pass Realm.delete() the Dog object, deleting it from the realm.

4. Map through the dogs to render a list of Text components that contain a dog's name and a "Delete Dog" button.

5. Add an onPress event on the "Delete Dog" button that calls the component's deleteDog() method.

Delete Multiple Objects

You can delete multiple objects from a realm in a couple of ways:

1. To delete all objects of a given object type from a realm, pass the results of useQuery(<ObjectType>) to the Realm.delete() method inside of a write transaction.

2. To delete many specific objects from a realm, pass Collection.filtered() to Realm.delete() inside of a write transaction.

In the following example of a DogList component, we:

1. Retrieve the realm instance using the useRealm() hook.

2. Set a variable myDogs to all the Dog objects by passing the Dog class to the useQuery() hook.

3. Create a component method deleteAllYoungDogObjects() that performs a write transaction. Within the write transaction, we set a variable, youngDogs, to the result of myDogs.filtered() with a query to obtain all dogs younger than three. Then pass youngDogs to realm.delete(), deleting all young dogs from the realm.

4. Create a component method deleteAllDogObjects() that performs a write transaction. Within the write transaction, we pass myDogs to realm.delete(), deleting all the dogs from the realm.

5. Map through the dogs to render a list of Text components that contain a dog's name and age.

6. Add an onPress event on the "Delete Young Dog Objects" button that calls deleteAllYoungDogObjects(), deleting all young dogs from the realm, which triggers a re-render and removes them from the UI.

7. Add an onPress event on the "Delete All Dog Objects" button that calls deleteAllDogObjects(), deleting every dog from the realm, which triggers a re-render and removes them from the UI.

Delete All Objects in a Realm

To delete all objects from the realm, call Realm.deleteAll() inside of a write transaction. This clears the realm of all object instances but does not affect the realm's schema.

In the following example of a DeleteProfileSettingsScreen component, we:

1. Get access to the opened realm instance by calling the useRealm() hook within the component.

2. Create a component method deleteAllData() that performs a write transaction and calls Realm.deleteAll(), deleting all objects from the realm.

3. Add an onPress event on the "Delete all data" button that calls deleteAllData().