Question
I've developed a universalObjectSet<T>
I keep a general repository here.
What I'd want to acquire is thename
an of the EntityKeyObjectSet<T>
so I may use it in theDataContext.GetObjectByKey
.
I've looked everywhere and looked very carefully, but I can't seem to locate this value anywhere in theObjectSet
class.
Accepted Answer
I spent some time looking for a decent approach to do this but was unable. To create Entity Keys for TryGetObjectByKey requests, I usually end up creating a GetEntityByKey extension method someplace. The main principle behind creating the entity key is as follows:
internal class Program
{
private static void Main(string[] args)
{
var dc = new AdventureWorksLT2008Entities();
object c;
dc.TryGetObjectByKey(GetEntityKey(dc.Customers, 23), out c);
var customer = c as Customer;
Console.WriteLine(customer.EmailAddress);
}
private static EntityKey GetEntityKey<T>(ObjectSet<T> objectSet, object keyValue) where T : class
{
var entitySetName = objectSet.Context.DefaultContainerName + "." + objectSet.EntitySet.Name;
var keyPropertyName = objectSet.EntitySet.ElementType.KeyMembers[0].ToString();
var entityKey = new EntityKey(entitySetName, new[] {new EntityKeyMember(keyPropertyName, keyValue)});
return entityKey;
}
}
You may be able to do something comparable. For the sake of simplicity, this example only considers a single field per EntityKey; if you wanted to use several value keys, you would need to useObjectSet<T>.ElementType.KeyMembers
then input the EntityKey constructor with all of your keys.
Popular Answer
Generic:
public class GenericoRepositorio<T> : IGenericoRepositorio<T> where T : class
{
protected readonly ObjectSet<T> ObjetoSet;
protected readonly ModeloContainer Contexto;
public GenericoRepositorio(ModeloContainer contexto)
{
Contexto = contexto;
ObjetoSet = Contexto.CreateObjectSet<T>();
}
public T Carregar(int id)
{
object objeto;
Contexto.TryGetObjectByKey(GetEntityKey(ObjetoSet, id), out objeto);
return (T)objeto;
}
private static EntityKey GetEntityKey<T>(ObjectSet<T> objectSet, object keyValue) where T : class
{
var entitySetName = objectSet.Context.DefaultContainerName + "." + objectSet.EntitySet.Name;
var keyPropertyName = objectSet.EntitySet.ElementType.KeyMembers[0].ToString();
var entityKey = new EntityKey(entitySetName, new[] { new EntityKeyMember(keyPropertyName, keyValue) });
return entityKey;
}
}
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