Create, Read, Update, Delete

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

Opening Isar

Before you can do anything, we need an Isar instance. Each instance requires a directory with write permission where the database file can be stored. If you don't specify a directory, Isar will find a suitable default directory for the current platform.

Provide all the schemas you want to use with the Isar instance. If you open multiple instances, you still have to provide the same schemas to each instance.

final isar = await Isar.open([RecipeSchema]);

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

Config	Description
name	Open multiple instances with distinct names. By default, "default" is used.
directory	The storage location for this instance. By default, NSDocumentDirectory is used for iOS and getDataDirectory for Android. Not required for web.
maxSizeMib	The maximum size of the database file in MiB. Isar uses virtual memory which is not an endless resource so be mindful with the value here. If you open multiple instances they share the available virtual memory so each instance should have a smaller maxSizeMib . The default is 2048.
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
compactOnLaunch	Conditions to check whether the database should be compacted when the instance is opened.
inspector	Enabled the Inspector for debug builds. For profile and release builds this option is ignored.

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.

The storage location of the database file is directory/name.isar

Reading from the database

Use IsarCollection instances to find, query, and create new objects of a given type in Isar.

For the examples below, we assume that we have a collection Recipe defined as follows:

@collection
class Recipe {
  Id? id;

  String? name;

  DateTime? lastCooked;

  bool? isFavorite;
}

Get a collection

All your collections live in the Isar instance. You can get the recipes collection with:

final recipes = isar.recipes;

That was easy! If you don't want to use collection accessors, you can also use the collection() method:

final recipes = isar.collection<Recipe>();

Get an object (by id)

We don't have data in the collection yet but let's pretend we do so we can get an imaginary object by the id 123

final recipe = await isar.recipes.get(123);

get() returns a Future with either the object or null if it does not exist. All Isar operations are asynchronous by default, and most of them have a synchronous counterpart:

final recipe = isar.recipes.getSync(123);

Warning

You should default to the asynchronous version of methods in your UI isolate. Since Isar is very fast, it is often acceptable to use the synchronous version.

If you want to get multiple objects at once, use getAll() or getAllSync():

final recipe = await isar.recipes.getAll([1, 2]);

Query objects

Instead of getting objects by id you can also query a list of objects matching certain conditions using .where() and .filter():

final allRecipes = await isar.recipes.where().findAll();

final favouires = await isar.recipes.filter()
  .isFavoriteEqualTo(true)
  .findAll();

➡️ Learn more: Queries

Modifying the database

It's finally time to modify our collection! To create, update, or delete objects, use the respective operations wrapped in a write transaction:

await isar.writeTxn(() async {
  final recipe = await isar.recipes.get(123)

  recipe.isFavorite = false;
  await isar.recipes.put(recipe); // perform update operations

  await isar.recipes.delete(123); // or delete operations
});

➡️ Learn more: Transactions

Insert object

To persist an object in Isar, insert it into a collection. Isar's put() method will either insert or update the object depending on whether it already exists in the collection.

If the id field is null or Isar.autoIncrement, Isar will use an auto-increment id.

final pancakes = Recipe()
  ..name = 'Pancakes'
  ..lastCooked = DateTime.now()
  ..isFavorite = true;

await isar.writeTxn(() async {
  await isar.recipes.put(pancakes);
})

Isar will automatically assign the id to the object if the id field is non-final.

Inserting multiple objects at once is just as easy:

await isar.writeTxn(() async {
  await isar.recipes.putAll([pancakes, pizza]);
})

Update object

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

So if we want to unfavorite our pancakes, we can do the following:

await isar.writeTxn(() async {
  pancakes.isFavorite = false;
  await isar.recipes.put(pancakes);
});

Delete object

Want to get rid of an object in Isar? Use collection.delete(id). The delete method returns whether an object with the specified id was found and deleted. If you want to delete the object with id 123, for example, you can do:

await isar.writeTxn(() async {
  final success = await isar.recipes.delete(123);
  print('Recipe deleted: $success');
});

Similarly to get and put, there is also a bulk delete operation that returns the number of deleted objects:

await isar.writeTxn(() async {
  final count = await isar.recipes.deleteAll([1, 2, 3]);
  print('We deleted $count recipes');
});

If you don't know the ids of the objects you want to delete, you can use a query:

await isar.writeTxn(() async {
  final count = await isar.recipes.filter()
    .isFavoriteEqualTo(false)
    .deleteAll();
  print('We deleted $count recipes');
});