public override TEntity Remove(TEntity entity)
{
var id = EntityOperation.GetSurrogateKey(entity);
if (EntityOperation <TEntity> .IsValidSurrogateKey(id))
{
var change = default(Change);
if (Changes.TryGetValue(id, out change))
{
if (change.Entity != entity)
{
ThrowAttachingMoreThanOneEntityException();
}
change.ChangeType = ChangeType.Remove;
}
else
{
var nonkeyValues = EntityOperation.NonkeyValues(entity);
change = new Change(entity, id, nonkeyValues, ChangeType.Remove);
Changes.Add(id, change);
}
}
else
{
AddedEntities.Remove(entity);
}
return(entity);
}
public override TEntity Attach(TEntity entity)
{
var id = EntityOperation.GetSurrogateKey(entity);
if (!EntityOperation <TEntity> .IsValidSurrogateKey(id))
{
throw new ArgumentException("Entity doesn't have valid ID.");
}
var change = default(Change);
if (Changes.TryGetValue(id, out change))
{
if (change.Entity != entity)
{
ThrowAttachingMoreThanOneEntityException();
}
change.ChangeType = ChangeType.Update;
}
else
{
var nonkeyValues = EntityOperation.NonkeyValues(entity);
change = new Change(entity, id, nonkeyValues, ChangeType.Update);
Changes.Add(id, change);
}
return(entity);
}
public override int SaveChanges()
{
var count = 0;
var relation = Table.Relation;
var addedEntities = AddedEntities.ToArray();
var changes = Changes.Values.ToArray();
AddedEntities.Clear();
Changes.Clear();
Local.Clear();
foreach (var entity in addedEntities)
{
AddToRelation(entity);
count++;
}
foreach (var change in changes)
{
switch (change.ChangeType)
{
case ChangeType.Add:
AddToRelation(change.Entity);
count++;
break;
case ChangeType.Remove:
if (!relation.Remove(change.Id))
{
ThrowRemovingNonexistingKeyException();
}
count++;
break;
case ChangeType.Update:
var values = EntityOperation.NonkeyValues(change.Entity);
if (!values.SequenceEqual(change.Original))
{
// Throws if the key not found.
relation[change.Id] = change.Entity;
count++;
}
break;
default:
throw new Exception("changeType = " + change.ChangeType);
}
}
return(count);
}