How to define Many-to-Many relationship through Fluent API Entity Framework?

The terms Left and Right in MapLeftKey and MapRightKey in the many-to-many mapping with Fluent API can be misunderstood and I guess your problem is caused by this misunderstanding. One might think that it means they describe the columns that are “left” and “right” in the many-to-many join table. That’s actually the case if you … Read more

What is Entity Framework fluent api?

Entity Framework 4.1 introduces the code first approach of writing database models. This is also called POCO (Plain Old CLR Objects). The idea is that you can build your database from these classes, rather then building the database first and creating a model from that. There are tons of good blog articles and MSDN documentation … Read more

One to one optional relationship using Entity Framework Fluent API

EF Code First supports 1:1 and 1:0..1 relationships. The latter is what you are looking for (“one to zero-or-one”). Your attempts at fluent are saying required on both ends in one case and optional on both ends in the other. What you need is optional on one end and required on the other. Here’s an … Read more

Entity Framework Code First – Advantages and disadvantages of Fluent Api vs Data Annotations [closed]

Everything what you can configure with DataAnnotations is also possible with the Fluent API. The reverse is not true. So, from the viewpoint of configuration options and flexibility the Fluent API is “better”. Configuration examples (for sure not a full list) which are possible in the Fluent API but not with DataAnnotations (as far as … Read more

Setting unique Constraint with fluent API?

On EF6.2, you can use HasIndex() to add indexes for migration through fluent API. https://github.com/aspnet/EntityFramework6/issues/274 Example modelBuilder .Entity<User>() .HasIndex(u => u.Email) .IsUnique(); On EF6.1 onwards, you can use IndexAnnotation() to add indexes for migration in your fluent API. http://msdn.microsoft.com/en-us/data/jj591617.aspx#PropertyIndex You must add reference to: using System.Data.Entity.Infrastructure.Annotations; Basic Example Here is a simple usage, adding an … Read more

How to do a join in linq to sql with method syntax?

var result = from sc in enumerableOfSomeClass join soc in enumerableOfSomeOtherClass on sc.Property1 equals soc.Property2 select new { SomeClass = sc, SomeOtherClass = soc }; Would be equivalent to: var result = enumerableOfSomeClass .Join(enumerableOfSomeOtherClass, sc => sc.Property1, soc => soc.Property2, (sc, soc) => new { SomeClass = sc, SomeOtherClass = soc }); As you can … Read more

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