When to use DbSet.Add() vs DbSet.Attach()

How to create a DbSet with a list of entities

DbSet.Add() adds a single Entity to DbSet. But there is no DbSet.AddRange() to add a list of entities. Is there a method I can call directly from EF that allows me to add a list of Entities? If not, is there any reason why EF does not provide such a method?

iterating over DbSet<TEntity> vs IQueryable<out T>

Using Entity Framework I select some data from a table and iterate over it with ...foreach... loop. I am wondering when is the data getting queried in the following examples?...Example 1....var countries = db.WorldCountries; foreach(var item in countries) { Console.WriteLine("Country: {0}", item.Country); } ...Example 2....var countries = db.Wo...

DbSet.Cast<TEntity>() Error: Cannot create a DbSet<IEntity> from a non-generic DbSet for objects of type 'Entity'

Version Info:...I am using C# 4.5, Entity Framework 6.0, and MEF....Code and Unit Test...I created a Test Project to explain the problem: ...https://skydrive.live.com/redir?resid=E3C97EC293A34048!2234...Please Open the UnitTest project and try to run TestIfItWorks() unit test....Problem...I want to convert a non-generic DbSet to its generic version...

Why does DbSet Add return an entity instance instead of void?

The ...DbSet<TEntity>.Add... method returns an entity. I would normally have expected an ...Add... operation to have a ...void... return type....When I look at the ...EntityFramework source code..., I see the following implementation:... public virtual TEntity Add(TEntity entity) { Check.NotNull(entity, "entity"); GetIntern...

What is the difference between DbSet<> and virtual DbSet<>?

In Entity Framework Code First, when I declare entities I have to use DbSet<> type of properties for that. For example:...public DbSet<Product> Products { get; set; } public DbSet<Customer> Customers { get; set; } ...Recently I've met DbSet<> declared as virtual....public virtual DbSet<Product> Products { get; set; } public virtual DbSet<Customer> ...

Dbset<TEntity>.Add(entity) assigns an ID and this results in a exception

For the following classes :...public Car { public int ID { get; set; } public string Brand {get; set; } } ...Normally when we do : ...Car c = new Car { Brand = "Jaguar" } ; // Point A context.Cars.Add(c); // Point B context.SaveChanges() // Point C ...At point B, the ID should remain 0, and an ID should only be assigned at point C. However...

DbSet.Attach(entity) vs DbContext.Entry(entity).State = EntityState.Modified

When I am in a detached scenario and get a dto from the client which I map into an entity to save it I do this:...context.Entry(entity).State = EntityState.Modified; context.SaveChanges(); ...For what is then the ...DbSet.Attach(entity)...or why should I use the .Attach method when EntityState.Modified already attaches the entity?

DbSet.Add & DbSet.Remove Versus using EntityState.Added & EntityState.Deleted

In entity framework 6 there are multiple way of adding / removing entities, for example for adding entities, we can use:-...b.Students.Add(student); db.SaveChanges(); ...OR...db.Entry(student).State = EntityState.Added; db.SaveChanges(); ...and similarly when Deleting object:-...db.Entry(studentToDelete).State = EntityState.Deleted; db.SaveChanges(...

Add manual DbSet to Partial class DbContext EntityFramework

I get an old project where I need to add a new functionnality. Edmx was generated a while ago and I don't want to edit it or generate it back. My idea is simply to add a new partial class with my two new DbSet:...public partial class MyContextClass { public virtual DbSet<Labels> Labels { get; set; } public virtual DbSet<LabelsWeight> Labels...

Entity Framework 6 DbSet AddRange vs IDbSet Add - How Can AddRange be so much faster?

I was playing around with Entity Framework 6 on my home computer and decided to try out inserting a fairly large amount of rows, around 430k. ...My first try looked like this, yes I know it can be better but it was for research anyway:...var watch = System.Diagnostics.Stopwatch.StartNew(); foreach (var event in group) { db.Events.Add(event); ...