I add an example for the InversePropertyAttribute. It cannot only be used for relationships in self referencing entities (as in the example linked in Ladislav’s answer) but also in the “normal” case of relationships between different entities: public class Book { public int ID {get; set;} public string Title {get; set;} [InverseProperty(“Books”)] public Author Author … Read more
If you don’t use lazy loading, you have the load the new Address explicitly (as you had to load it explicitly (with Include, for example), when you loaded the Person initially): context.Entry(myPerson).Reload(); // If the person refers to another Address in the DB // myPerson.Address will be null now if (myPerson.Address == null) context.Entry(myPerson).Reference(p => … Read more
The problem is this one: MyEntity has an ID of 0 since it’s a new MyEntity. The Group is also new and contain a reference to MyEntity. So, MyEntity contains a list of Group which contain a reference back to MyEntity. The problem is that MyEntity.Group.MyEntity seems to be “new and not the same” as … Read more
You just need to set Configuration.ValidateOnSaveEnabled = false in your context class before calling SaveChanges(). context.Configuration.ValidateOnSaveEnabled = false; context.SaveChanges();
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
var listOfRoleId = user.Roles.Select(r => r.RoleId); var roles = db.Roles.Where(r => listOfRoleId.Contains(r.RoleId));
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
This is too long question. You should break your problem into multiple separate questions next time. Code-first x Model-first x Database-first You are a database guy so the best approach for you is an incremental database-first approach where you define the stuff in DB (or VS Database tools) and update your model from the database. … Read more
It may occur because: DbContext configured with an incorrect connection string The entity specified is actually not mapped in configuration
For EF 5 use DbContext‘s ChangeTracker: public bool HasUnsavedChanges() { return this.ChangeTracker.Entries().Any(e => e.State == EntityState.Added || e.State == EntityState.Modified || e.State == EntityState.Deleted); } For EF 6 use the ChangeTracker.HasChanges() method which will also detect changes in many to many relationships: public bool HasUnsavedChanges() { return this.ChangeTracker.HasChanges(); }