One-to-one foreign key associations are not supported by Entitiy Framework. You must remove the foreign key and use shared primary keys (primary key of the dependent is its foreign key to the principal at the same time): public class StandardRack { public int Id {get;set} public StandardRelay StandardRelay {get;set} } public class StandardRelay { public … Read more
The database will only be created when you actually use the context. If you have overridden the Seed method in your initializer as follows: protected override void Seed(MyContext context){…} The Seed code will only run when you use an instance of MyContext. That is why it works when you use var ctx = new MyContext(); … Read more
Let’s assume that you have a collection of the properties to be excluded: var excluded = new[] { “property1”, “property2” }; With EF5 on .NET 4.5 you can do this: var entry = context.Entry(obj); entry.State = EntityState.Modified; foreach (var name in excluded) { entry.Property(name).IsModified = false; } This uses a new feature of EF5 on … Read more
With Entity Framework Core (tested with Version 2.1) you can get the current context using // DbSet<MyModel> myDbSet var context = myDbSet.GetService<ICurrentDbContext>().Context; How to get a DbContext from a DbSet in EntityFramework Core 2.0
For those of you who would still have this error with all keys properly defined, have a look at your entities and make sure you don’t leave a datetime field with a null value.
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(); }
Looks like the repository pattern is solution for everything … Repository is not a silver bullet! I’m using the repository pattern with EF everyday because when I started my current project several months ago it looked like recommended solution. My conclusions: Repository makes interaction with EF much harder. Just browse questions related to EF tags … Read more
No you cannot do that in mapping. Typical workaround is simple extension method: public static IQueryable<Car> BuildCar(this IQueryable<Car> query) { return query.Include(x => x.Wheels) .Include(x => x.Doors) .Include(x => x.Engine) .Include(x => x.Bumper) .Include(x => x.Windows); } Now every time you want to query Car with all relations you will just do: var query = … Read more
Try this: var sql = @”Update [User] SET FirstName = @FirstName WHERE Id = @Id”; ctx.Database.ExecuteSqlCommand( sql, new SqlParameter(“@FirstName”, firstname), new SqlParameter(“@Id”, id));
The following query will get the count and page results in one trip to the database, but if you check the SQL in LINQPad, you’ll see that it’s not very pretty. I can only imagine what it would look like for a more complex query. var query = ctx.People.Where (p => p.Name.StartsWith(“A”)); var page = … Read more