I know that EF Code First Migrations is relatively new tool but don’t forget about you are still in .NET. So you can use: if (System.Diagnostics.Debugger.IsAttached == false) { System.Diagnostics.Debugger.Launch(); } After that you can see your InnerException. Or you can use try…catch statement like this: Exception handling Entity Framework
Entity Framework would use ICollection<T> because it needs to support Add operations, which are not part of the IEnumerable<T> interface. Also note that you were using ICollection<T>, you were merely exposing it as the List<T> implementation. List<T> brings along with it IList<T>, ICollection<T>, and IEnumerable<T>. As for your change, exposing via the interface is a … Read more
Turns out that Entity Framework will assume that any class that inherits from a POCO class that is mapped to a table on the database requires a Discriminator column, even if the derived class will not be saved to the DB. The solution is quite simple and you just need to add [NotMapped] as an … Read more
Put this in your custom DbContext class: protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Estate>().ToTable(“Estate”); } If your tables are not created on startup, this is why. You need to tell the DbContext about them in the OnModelCreating method override. You can either do custom per-entity mappings here, or separate them out into separate EntityTypeConfiguration<T> classes.
MaxLength is used for the Entity Framework to decide how large to make a string value field when it creates the database. From MSDN: Specifies the maximum length of array or string data allowed in a property. StringLength is a data annotation that will be used for validation of user input. From MSDN: Specifies the … Read more
This is an option: dbContext.Entry(entity).State = EntityState.Detached;
While you are in debug mode within the catch {…} block open up the “QuickWatch” window (ctrl+alt+q) and paste in there: ((System.Data.Entity.Validation.DbEntityValidationException)ex).EntityValidationErrors This will allow you to drill down into the ValidationErrors tree. It’s the easiest way I’ve found to get instant insight into these errors. For Visual 2012+ users who care only about the … Read more
So far, I know of these effects. Lazy Loading: Any virtual ICollections will be lazy-loaded unless you specifically mark them otherwise. More efficient change tracking. If you meet all the following requirements then your change tracking can use a more efficient method by hooking your virtual properties. From the link: To get change tracking proxies, … Read more
You can do it by manually edit code first migration: public override void Up() { AddColumn(“dbo.Events”, “Active”, c => c.Boolean(nullable: false, defaultValue: true)); }
You can have multiple contexts for single database. It can be useful for example if your database contains multiple database schemas and you want to handle each of them as separate self contained area. The problem is when you want to use code first to create your database – only single context in your application … Read more