EntityTypeConfiguration<TEntityType>.HasOptional<TTargetEntity> Method

Entity Framework 5.0

Configures an optional relationship from this entity type. Instances of the entity type will be able to be saved to the database without this relationship being specified. The foreign key in the database will be nullable.

Namespace:  System.Data.Entity.ModelConfiguration
Assembly:  EntityFramework (in EntityFramework.dll)

public OptionalNavigationPropertyConfiguration<TEntityType, TTargetEntity> HasOptional<TTargetEntity>(
	Expression<Func<TEntityType, TTargetEntity>> navigationPropertyExpression
where TTargetEntity : class

Type Parameters


The type of the entity at the other end of the relationship.


Type: System.Linq.Expressions.Expression<Func<TEntityType, TTargetEntity>>

A lambda expression representing the navigation property for the relationship. For example, in C# t => t.MyProperty and in Visual Basic .Net Function(t) t.MyProperty.

Return Value

Type: System.Data.Entity.ModelConfiguration.Configuration.OptionalNavigationPropertyConfiguration<TEntityType, TTargetEntity>
A configuration object that can be used to further configure the relationship.