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Object Models & Schemas - .NET SDK

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  • Object Types & Schemas
  • Schemas
  • Working with Realm Objects

Realm applications model data as objects composed of property-value pairs that each contain one or more primitive data types or other Realm objects. Realm objects are essentially the same as regular objects, but they inherit from RealmObject or EmbeddedObject and include additional features like real-time updating data views and reactive change event handlers.

Every Realm object has an object type that refers to the object's class. Objects of the same type share an object schema that defines the properties and relationships of those objects.

In C#, you typically define object schemas by using the C# class declarations. When Realm is initialized, it discovers the Realm objects defined in all assemblies that have been loaded and generates schemas accordingly. This is the simplest approach to defining a schema, and is generally the least error-prone. However, this approach includes all loaded Realm objects, and there may be cases where you only want to use a subset of classes, or to customize Realm object schemas. To do this, you can programmatically define a schema.

Note

.NET does not load an assembly until you reference a class in it, so if you define your object models in one assembly and instantiate Realm in another, be sure to call a method in the assembly that contains the object models before initialization. Otherwise, Realm will not discover the objects when it first loads.

The following code block shows an object schema that describes a Dog. Every Dog object must include a Name and may optionally include the dog's Age, Breed and a list of people that represents the dog's Owners.

public class Dog : RealmObject
{
[PrimaryKey]
[MapTo("_id")]
public ObjectId Id { get; set; }
[Required]
public string Name { get; set; }
public int Age { get; set; }
public string Breed { get; set; }
public IList<Person> Owners { get; }
}
public class Person : RealmObject
{
[PrimaryKey]
[MapTo("_id")]
public ObjectId Id { get; set; }
[Required]
public string Name { get; set; }
// etc...
/* To add items to the IList<T>:
var dog = new Dog();
var caleb = new Person { Name = "Caleb" };
dog.Owners.Add(caleb);
*/
}

Note

To define a collection of objects within an object, use an IList<T> with only a getter. You do not need to initialize it in the constructor, as realm will generate a collection instance the first time the property is accessed.

Note

Further Examples

The CRUD - .NET SDK section provides examples of creating, reading, updating, filtering, and deleting Realm objects.

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