为实体设置主键而不影响数据库

Question

I'm working on an ASP.NET MVC project, I use Entity Framework (Database First), I created a data model depend on SQL server database, I created a Table in the database and I updated the data model from the database, and when I try to add a record to the new table I created (this table doesn't have a PK) I got an error, when I search about the error I Understood that in Entity Framework need to have a PK for Entity.

So I ASK if I can set a Primary Key for an Entity without affect database, or any other solution to solve this problem.

Answer 1

You can use partial Class for set Key and without effect Original Model and Database

// orginal class **Entity** `YourEntity.cs`
public class YourEntity
{
   public int Id { get; set; }
}

Then create a new Class must name different ordinal class ex YourEntityMeta.cs it is physical name

// must change name ordinal class `YourEntity.cs` but add **partial** keyword
[MetadataType(typeof(Metadata))]
public partial class YourEntity
{
   sealed class Metadata
   {
      [Key]
      public int Id { get; set; }
   }
}

Answer 2

Entity Framework always needs a primary key column with name id. Add a column (id) in the database table and set "Is Identity: true" for it. Then update the database model of your project.