Lists - .NET SDK
Overview
A Realm list implements
IList<T>,
and contains zero or more instances of a
Realm type. Like a C# List,
a Realm collection is homogenous (all objects in a collection are of
the same type).
Lists
Realm objects can contain lists of any supported data type.
You create a collection by defining a getter-only property of type
IList<T>,
where T can be any data type (except other collections). A list of realm
objects represents a to-many relationship
between two Realm types, the containing class and the type in the list.
Lists are mutable: within a write transaction, you can add and remove elements on a list.
Lists and Nullability
Deleting an object from the database will remove it from any lists
where it existed. Therefore, a list of objects will never contain deleted objects.
However, lists of primitive types can contain null values. If you do not
want to allow null values in a list, then either use non-nullable types in
the list declaration (for example, use IList<double> instead of
IList<double?>). If you are using the older schema
type definition (your classes derive from the RealmObject base class),
or you do not have nullability enabled, use the
[Required] attribute if the list
contains nullable reference types, such as string or byte[].
Important
Not Supported with Sync
Local-only realms support collections of nullable (optional) values,
but Sync does not.
For more information, refer to Required and Optional Properties.
Watching For Changes
You can use the INotifyCollectionChanged.CollectionChanged event on a list to watch for changes to the list, and the INotifyPropertyChanged.PropertyChanged event to watch for changes to specific properties in the list.
In the following code example, we have a class with an
IList<string> property named StringList. We set up event
handlers for both the CollectionChanged and PropertyChanged events:
var list = container.StringList.AsRealmCollection(); list.CollectionChanged += (sender, e) => { Console.WriteLine($"List {sender} changed: {e.Action}"); }; list.PropertyChanged += (sender, e) => { Console.WriteLine($"Property changed on {sender}: {e.PropertyName}"); };