Sets - .NET SDK
On this page
New in version 10.2.0.
Overview
A Realm set, like the C#
HashSet<>,
is an implementation of
ICollection<>
and
IEnumerable<>.
It supports values of any
Realm type except collections.
To define a set, use a getter-only ISet<TValue> property, where TValue
is any of the supported types.
Deleting an object from the database will remove it from any sets
in which it existed. Therefore, a set of objects will never contain null objects.
However, sets of primitive types can contain null values. If you do not
want to allow null values in a set, then either use non-nullable types in
the set declaration (for example, use ISet<double> instead of
ISet<double?>), or add the
[Required] attribute if the set
contains nullable reference types, such as string or byte[].
Important
Not Supported with Sync
Local-only Realm Databases support collections of nullable (optional) values,
but Sync does not.
Set Types
The following code shows examples of set types:
public partial class Inventory : IRealmObject { // A Set can contain any Realm-supported type, including // objects that inherit from RealmObject public ISet<Plant> PlantSet { get; } public ISet<double> DoubleSet { get; } // Nullable types are supported in local-only // Realms, but not with Sync public ISet<int?> NullableIntsSet { get; } // For C# types that are implicitly nullable, you can // use the [Required] attribute to prevent storing null values [] public ISet<string> RequiredStrings { get; } }
Usage Example
The following code shows how to create, write to, and read from Sets.
var inventory = new Inventory(); inventory.PlantSet.Add(new Plant() { Name = "Prickly Pear" }); inventory.DoubleSet.Add(123.45); realm.Write(() => { realm.Add<Inventory>(inventory); }); // convert the Plant Set to an IQueryable and apply a filter var pricklyPear = inventory.PlantSet.AsRealmQueryable() .Where(p => p.Name == "Prickly Pear"); // Alternatively, apply a filter directly on the Plant Set var pricklyPearPlants = inventory.PlantSet .Filter("Name == 'Prickly Pear'"); // Find all Inventory items that have at least one value in their // DoubleSet that is larger than 5 var moreThan100 = realm.All<Inventory>() .Filter("DoubleSet.@values > 100");
Data Binding
Like other Realm collections, ISet implements INotifyCollectionChanged,
so you can use it in data-binding scenarios (for example, when
watching for changes).