EntityCollection<TEntity> Class

Definition

generic <typename TEntity>
 where TEntity : classpublic ref class EntityCollection sealed : System::Data::Objects::DataClasses::RelatedEnd, System::Collections::Generic::ICollection<TEntity>, System::Collections::Generic::IEnumerable<TEntity>, System::ComponentModel::IListSource

[System.Serializable]
public sealed class EntityCollection<TEntity> : System.Data.Objects.DataClasses.RelatedEnd, System.Collections.Generic.ICollection<TEntity>, System.Collections.Generic.IEnumerable<TEntity>, System.ComponentModel.IListSource where TEntity : class

type EntityCollection<'Entity (requires 'Entity : null)> = class
    inherit RelatedEnd
    interface ICollection<'Entity (requires 'Entity : null)>
    interface seq<'Entity (requires 'Entity : null)>
    interface IEnumerable
    interface IListSource

Public NotInheritable Class EntityCollection(Of TEntity)
Inherits RelatedEnd
Implements ICollection(Of TEntity), IEnumerable(Of TEntity), IListSource

Type Parameters

Inheritance

Object

RelatedEnd

EntityCollection<TEntity>

Attributes

SerializableAttribute

Implements

ICollection<TEntity> IEnumerable<T> IEnumerable<TEntity> IEnumerable IListSource

Examples

This example is based on the . To run the code in this example, you must have already added the AdventureWorks Sales Model to your project and configured your project to use the Entity Framework. To do this, complete the procedures in How to: Manually Configure an Entity Framework Project and How to: Manually Define the Model and Mapping Files.

This example does the following:

1. Creates two new SalesOrderHeader entities and adds them to the Contact entity.

2. Gets all related ends from the RelationshipManager that is associated with the Contact entity.

3. Iterates through the collection of IRelatedEnds.

4. Gets the EntityCollection<TEntity> for each related end.

5. Uses the Remove method to remove one of the entities from the collection.

6. Calls the Contains method to determine whether the object was removed from the collection.

7. Uses the Add method to add the entity back.

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    Contact contact = new Contact();

    // Create a new SalesOrderHeader.
    SalesOrderHeader newSalesOrder1 = new SalesOrderHeader();
    // Add SalesOrderHeader to the Contact.
    contact.SalesOrderHeaders.Add(newSalesOrder1);

    // Create another SalesOrderHeader.
    SalesOrderHeader newSalesOrder2 = new SalesOrderHeader();
    // Add SalesOrderHeader to the Contact.
    contact.SalesOrderHeaders.Add(newSalesOrder2);

    // Get all related ends
    IEnumerable<IRelatedEnd> relEnds =
        ((IEntityWithRelationships)contact)
        .RelationshipManager.GetAllRelatedEnds();

    foreach (IRelatedEnd relEnd in relEnds)
    {
        // Get Entity Collection from related end
        EntityCollection<SalesOrderHeader> entityCollection =
            (EntityCollection<SalesOrderHeader>)relEnd;

        Console.WriteLine("EntityCollection count: {0}",
            entityCollection.Count);
        // Remove the first entity object.
        entityCollection.Remove(newSalesOrder1);

        bool contains = entityCollection.Contains(newSalesOrder1);

        // Write the number of items after one entity has been removed
        Console.WriteLine("EntityCollection count after one entity has been removed: {0}",
            entityCollection.Count);

        if (contains == false)
            Console.WriteLine("The removed entity is not in in the collection any more.");

        //Use IRelatedEnd to add the entity back.
        relEnd.Add(newSalesOrder1);
        Console.WriteLine("EntityCollection count after an entity has been added again: {0}",
            entityCollection.Count);
    }
}

Using context As New AdventureWorksEntities()
    Dim contact As New Contact()

    ' Create a new SalesOrderHeader. 
    Dim newSalesOrder1 As New SalesOrderHeader()
    ' Add SalesOrderHeader to the Contact. 
    contact.SalesOrderHeaders.Add(newSalesOrder1)

    ' Create another SalesOrderHeader. 
    Dim newSalesOrder2 As New SalesOrderHeader()
    ' Add SalesOrderHeader to the Contact. 
    contact.SalesOrderHeaders.Add(newSalesOrder2)

    ' Get all related ends 
    Dim relEnds As IEnumerable(Of IRelatedEnd) = DirectCast(contact, IEntityWithRelationships).RelationshipManager.GetAllRelatedEnds()

    For Each relEnd As IRelatedEnd In relEnds
        ' Get Entity Collection from related end 
        Dim entityCollection As EntityCollection(Of SalesOrderHeader) = DirectCast(relEnd, EntityCollection(Of SalesOrderHeader))

        Console.WriteLine("EntityCollection count: {0}", entityCollection.Count)
        ' Remove the first entity object. 
        entityCollection.Remove(newSalesOrder1)

        Dim contains As Boolean = entityCollection.Contains(newSalesOrder1)

        ' Write the number of items after one entity has been removed 
        Console.WriteLine("EntityCollection count after one entity has been removed: {0}", entityCollection.Count)

        If contains = False Then
            Console.WriteLine("The removed entity is not in in the collection any more.")
        End If

        'Use IRelatedEnd to add the entity back. 
        relEnd.Add(newSalesOrder1)
        Console.WriteLine("EntityCollection count after an entity has been added again: {0}", entityCollection.Count)
    Next
End Using

Remarks

An EntityCollection<TEntity> is a collection of objects of a particular entity type that represents the "many" end of a one-to-many or many-to-many relationship.

An EntityCollection<TEntity> is returned by a navigation property. Use the Load method to load related objects into an EntityCollection<TEntity>. To store an unrelated collection of objects of a specific entity type, such as the result of an ObjectQuery<T>, use an instance of the List<T> class.

An EntityCollection<TEntity> might have a corresponding EntityReference<TEntity>. When an EntityCollection<TEntity> and an EntityReference<TEntity> model opposite ends of the same relationship, the integrity of the relationship is maintained at the object level. The two classes are synchronized automatically.

This class cannot be inherited.

Constructors

Properties

Methods

Events

Explicit Interface Implementations

Extension Methods

Applies to