Create, Read, Update, Delete

When you have your Collections defined, learn how to manipulate them!

Opening Isar

Before you can do anything, you have to open an Isar instance. Each instance needs a directory with write permission.

final isar = await Isar.open(
  schemas: [ContactSchema],
  directory: 'some/directory',
);

You can use the default config or provide some of the following parameters.

Config	Description
name	You can open multiple instances with distinct names. By default, "isar" is used.
schemas	A list of all collection schemas you want to use. All instances need to use the same schemas.
directory	The storage location for this instance. You can pass a relative or absolute path. By default, NSDocumentDirectory is used for iOS and getDataDirectory for Android. The final location is path/name. Not required for web.
relaxedDurability	Relaxes the durability guarantee to increase write performance. In case of a system crash (not app crash), it is possible to lose the last committed transaction. Corruption is not possible

You can either store the Isar instance in a global variable or use your favorite dependency injection package to manage it.

If an instance is already open, calling Isar.open() will yield the existing instance regardless of the specified parameters. That's useful for using isar in an isolate.

TIP

Consider using the path_provider package to get a valid path on all platforms.

Collections

The Collection object is how you find, query, and create new records of a given type.

Get a collection

All your collections live in the Isar instance. Remember the Contact class we annotated before with @Collection(). You can get the contacts collection with:

final contacts = isar.contacts;

That was easy!

Get a record (by id)

final contact = await contacts.get(someId);

get() returns a Future. All Isar operations are asynchronous by default. Most operations have a synchronous counterpart:

final contact = contacts.getSync(someId);

TIP

It is recommended to use the asynchronous version of the method in your UI isolate. Since Isar is very fast, it is often fine to use the synchronous version.

Query records

Find a list of records matching given conditions using .where() and .filter():

final allContacts = await contacts.where().findAll();

final starredContacts = await contacts.filter()
  .isStarredEqualTo(true)
  .findAll();

➡️ Learn more: Queries

Modifying the database

To create, update, or delete records, use the respective operations wrapped in a write transaction:

await isar.writeTxn(() async {
  final contact = await contacts.get(someId)

  contact.isStarred = false;
  await contacts.put(contact); // perform update operations

  await contact.delete(contact.id); // or delete operations
});

➡️ Learn more: Transactions

Create a new record

When an object is not yet managed by Isar, you need to .put() it into a collection. If the id field is null, Isar will use an auto-increment id.

final newContact = Contact()
  ..firstName = "Albert"
  ..lastName = "Einstein"
  ..isStarred = true;
await isar.writeTxn(() async {
  await contacts.put(newContact);
})

Isar will automatically assign the new id to the object if the id field is not read-only.

Update a record

Both creating and updating works with yourCollection.put(yourObject). If the id is null (or does not exist), the object is inserted, otherwise it is updated.

Delete records

await isar.writeTxn(() async {
  contacts.delete(contact.id);
});

or:

await isar.writeTxn(() async {
  final idsOfUnstarredContacts = await contacts.filter()
    .isStarredEqualTo(false)
    .idProperty()
    .findAll();

  contacts.deleteAll(idsOfUnstarredContacts);
});