I've created a generic ObjectSet<T> in my generic repository.
What I would like to get is the name of the EntityKey of ObjectSet<T> so that I can use it in the DataContext.GetObjectByKey.
I've searched around and dug deep, but I can't seem to find this value anywhere in the ObjectSet class.
I looked a while ago for a nice way to do this and failed to find one. I generally end up building a GetEntityByKey extension method somewhere and within that, contatenating strings to build Entity Keys for TryGetObjectByKey calls. The general idea for building the entity key goes something like this:
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 similar. This example assumes a single field per EntityKey for simplicity - for multiple value keys you would need to do something slightly more sophisticated with ObjectSet<T>.ElementType.KeyMembers and pass all your keys into the EntityKey constructor.
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;
}
}
See this post that I made regarding getting the EntitySetName. For my repository, I create a property that gets the entity set name for the specific class name to do exactly what you are trying to do.
This should give you all the generic arguments (the types) for the ObjectSet:
objectSet.GetType().GetGenericArguments().First()
var objContext = ((IObjectContextAdapter)this.context).ObjectContext;
var objSet = objContext.CreateObjectSet<T>();
var entityKey = objContext.CreateEntityKey(objSet.EntitySet.Name, entityToUpdate);
Object foundEntity;
var exits = objContext.TryGetObjectByKey(entityKey, out foundEntity);
if (exits && this.dbset.Local != null && this.dbset.Local.Contains(foundEntity) &&this.dbset.Local.Any())
{
if (entityKey.EntityKeyValues != null && entityKey.EntityKeyValues.Any())
{
DbEntityEntry<T> entry = this.context.Entry(this.dbset.Find(entityKey.EntityKeyValues.FirstOrDefault().Value));
entry.CurrentValues.SetValues(entityToUpdate);
}
}
this.context.SaveChanges();
Tested with EF 6.
It will return an array of objects for each primary key value for the given DbEntityEntry.
Their maybe edge cases where this does not work - but for my simple needs works great.
Hope this helps someone else.
object[] GetPrimaryKeyValue(DbEntityEntry entry)
{
List<object> key = new List<object>();
var objectStateEntry = ((IObjectContextAdapter)this).ObjectContext.ObjectStateManager.GetObjectStateEntry(entry.Entity);
if (objectStateEntry.EntityKey.EntityKeyValues != null && objectStateEntry.EntityKey.EntityKeyValues.Length==1)
{
key.Add(objectStateEntry.EntityKey.EntityKeyValues[0].Value);
}
else
{
if (objectStateEntry.EntitySet.ElementType.KeyMembers.Any())
{
foreach (var keyMember in objectStateEntry.EntitySet.ElementType.KeyMembers)
{
if (entry.CurrentValues.PropertyNames.Contains(keyMember.Name))
{
var memberValue = entry.CurrentValues[keyMember.Name];
if (memberValue != null)
{
key.Add(memberValue);
}
}
}
}
}
return key.ToArray();
}
I had a tough time trying to do almost the same thing, getting the primary key name and value at runtime when the type is unknown. I was just get trying to implement an auditing scheme for deletes, and every solution i find involves superfluous code that I dont really understand. The EntityKey is not available from a DbContext, which is also confusing and annoying. The last 5 lines may save you 5 hours and 1 yr of baldness. I am not attempting this for Inserts, so if you do, you need to inspect those values carefully as they may be 0 or null.
foreach(var entry in ChangeTracker.Entries<IAuditable>())
{
...
case EntityState.Deleted:
var oc = ((IObjectContextAdapter)this).ObjectContext; //this is a DbContext
EntityKey ek = oc.ObjectStateManager.GetObjectStateEntry(entry.Entity).EntityKey;
var tablename = ek.EntitySetName;
var primaryKeyField = ek.EntityKeyValues[0].Key; //assumes only 1 primary key
var primaryKeyValue = ek.EntityKeyValues[0].Value;
