To persist an entity you usually add it to it’s DbSet in the context. For example var bar = new Bar(); bar.Name = “foo”; var context = new Context(); context.Bars.Add(bar); Surprisingly, querying context.Bars, the just added entity cannot be found var howMany = context.Bars.Count(b => b.Name == “foo”); // howMany == 0 After context.SaveChanges() the … Read more
A scenario where using DbSet<T>.Create() makes sense is attaching an existing entity to the context and then leverage lazy loading of related entities. Example: public class Parent { public int Id { get; set; } public virtual ICollection<Child> Children { get; set; } } public class Child { public int Id { get; set; } … Read more
The following usually works: Context.Refresh(RefreshMode.StoreWins, _ Context.ObjectStateManager.GetObjectStateEntries()) It sometimes causes problems with EntityRelations. look at my comment for further details.
This is now possible in EF Core 5.0 using the ExcludeFromMigrations() method, but strangely enough you have to call the ToTable() method and then use the TableBuilder. https://devblogs.microsoft.com/dotnet/announcing-entity-framework-core-efcore-5-0-rc1/#exclude-tables-from-migrations public class ReportingContext : DbContext { public DbSet<User> Users { get; set; } protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<User>().ToTable(nameof(Users), t => t.ExcludeFromMigrations()); } }
You can create a partial class, separate from the EF generated class, to store the metadata in. //Contact.cs – The original auto-generated file [System.ComponentModel.DataAnnotations.MetadataType(typeof(ContactMetadata))] public partial class Contact { public int ContactID { get; set; } public string ContactName { get; set; } public string ContactCell { get; set; } } //ContactMetadata.cs – New, seperate … Read more
Possible reason why you don’t get cascading delete is that your relationship is optional. Example: public class Category { public int CategoryId { get; set; } } public class Product { public int ProductId { get; set; } public Category Category { get; set; } } In this model you would get a Product table … Read more
The newly added object is in the local DataSource, since it’s not persisted yet in the database, so you may say: EntityObject search = ents.EntityObject.FirstOrDefault(o => o.Id == theId) ?? ents.EntityObject.Local.FirstOrDefault(o => o.Id == theId);
Find calls DetectChanges internally, SingleOrDefault (or generally any query) doesn’t. DetectChanges is an expensive operation, so that’s the reason why Find is slower (but it might become faster if the entity is already loaded into the context because Find would not run a query but just return the loaded entity). If you want to use … Read more
All relationships in your model are required because all foreign key properties (CountryId, RegionId, CityId) are not nullable. For required one-to-many relationships EF will enable cascading delete by convention. Country and Region have multiple delete paths to the Store table, for example if you delete a Country the related Stores can be deleted via three … Read more
You delete your old .tt files You open your edmx file in designer mode (so you can see your model) Right click on a free space Select Add Code Generation Item In the dialog select “EF 6.x DbContext Code Generation Item” (something like this) Save your edmx and all classes will be generated for you, … Read more