When you load the entity from the context it keeps an additional data structure – let’s call it entry. The entry contains two set of values – original values and current values. When you execute the SaveChanges operation EF goes through your customer entities and updates current values in the entry so that they match … Read more
Yes. SaveChanges uses transaction internally. Use TransactionScope to wrap multiple calls to SaveChanges Example: using(var scope = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions { IsolationLevel = IsolationLevel.ReadCommitted })) { // Do something context.SaveChanges(); // Do something else context.SaveChanges(); scope.Complete(); }
You can map each table to its own schema by fluent mapping only. In your DbContext subtype you should override OnModelCreating (if you haven’t done so already) and add statements like this: modelBuilder.Entity<Department>() .ToTable(“t_Department”, “school”); Entities that you don’t map like this explicitly will be placed in the default dbo schema, or you can provide … Read more
Using any context.XyzAsync() method is only useful if you either await the called method or return control to a calling thread that’s doesn’t have context in its scope. A DbContext instance isn’t thread-safe: you should never ever use it in parallel threads. Which means, just for sure, never use it in multiple threads anyway, even … Read more
Setting AutoDetectChangesEnabled to false doesn’t disable change tracking. (That’s what the AsNoTracking() extension method would do.) It just disables the automatic call of DetectChanges that would otherwise occur in many DbContext API methods. But DetectChanges isn’t the only method that participates in change tracking. However, if you don’t call it manually at the right places … Read more
public void RejectChanges() { foreach (var entry in ChangeTracker.Entries()) { switch (entry.State) { case EntityState.Modified: case EntityState.Deleted: entry.State = EntityState.Modified; //Revert changes made to deleted entity. entry.State = EntityState.Unchanged; break; case EntityState.Added: entry.State = EntityState.Detached; break; } } } Update: Some users suggest to add .ToList() to avoid ‘collection was modified’ exception. But I believe … Read more
It will work with your method. Or subclass it (from msdn forum) public class YourContext : DbContext { public YourContext() : base(“YourConnectionString”) { // Get the ObjectContext related to this DbContext var objectContext = (this as IObjectContextAdapter).ObjectContext; // Sets the command timeout for all the commands objectContext.CommandTimeout = 120; } }
In fact this is two questions in one: When should I Dispose() of a context? What should be the lifespan of my context? Answers: Never 1. using is an implicit Dispose() in a try-finally block. A separate Dispose statement can be missed when an exception occurs earlier. Also, in most common cases, not calling Dispose … Read more
I think you should not follow the first article, and I will tell you why. Following the second approach you’re loosing pretty much every feature that Entity Framework provides via the DbContext, including its 1st-level cache, its identity map, its unit-of-work, and its change tracking and lazy-loading abilities. That’s because in the scenario above, a … Read more
One cheap easy way of cloning an entity is to do something like this: var originalEntity = Context.MySet.AsNoTracking() .FirstOrDefault(e => e.Id == 1); Context.MySet.Add(originalEntity); Context.SaveChanges(); the trick here is AsNoTracking() – when you load an entity like this, your context do not know about it and when you call SaveChanges, it will treat it like … Read more