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CRUD - React Native SDK

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  • Transaction Lifecycle

Within a RealmProvider, you can access a realm with the useRealm() hook. Then, you can create Realm objects using a Realm.write() transaction block.

All operations within a write transaction are atomic. If an operation in the write transaction fails, the whole transaction fails, Realm throws an error, and no changes from the transaction block are applied to the realm.

Every write operation must occur in a write transaction.

const CreatePersonInput = () => {
  const [name, setName] = useState('');
  const realm = useRealm();
  const handleAddPerson = () => {
    realm.write(() => {
      realm.create('Person', {_id: PERSON_ID, name: name, age: 25});
    });
  };
  return (
    <>
      <TextInput value={name} onChangeText={setName}  />
      <Button
        onPress={() => handleAddPerson()}
        title='Add Person'
      />
    </>
  );
};

Transaction Lifecycle

A given realm only processes one write transaction at a time. When you make a write transaction, the realm adds the transaction to a queue. The realm evaluates each transaction in the order it arrived.

After processing a transaction, Realm either commits it or cancels it:

  • After a commit, the realm applies all operations in the transaction. Once applied, the realm automatically updates live queries. It notifies listeners of created, modified, and deleted objects.

    • When using Sync, the SDK also queues the changes to send to Atlas App Services. The SDK sends these changes when a network is available.

    • After a commit, objects and collections returned by useQuery or useObject rerender to include relevant changes.

  • Realm does not apply any operations in a cancelled transaction. Realm cancels a transaction if an operation fails or is invalid.

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