For Mapping Composite primary key using Entity framework we can use two approaches.
1) By Overriding the OnModelCreating() Method
For ex: I have the model class named VehicleFeature as shown below.
public class VehicleFeature
{
public int VehicleId { get; set; }
public int FeatureId{get;set;}
public Vehicle Vehicle{get;set;}
public Feature Feature{get;set;}
}
The Code in my DBContext would be like ,
public class VegaDbContext : DbContext
{
public DbSet<Make> Makes{get;set;}
public DbSet<Feature> Features{get;set;}
public VegaDbContext(DbContextOptions<VegaDbContext> options):base(options)
{
}
// we override the OnModelCreating method here.
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<VehicleFeature>().HasKey(vf=> new {vf.VehicleId, vf.FeatureId});
}
}
2) By Data Annotations.
public class VehicleFeature
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public int VehicleId { get; set; }
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public int FeatureId{get;set;}
public Vehicle Vehicle{get;set;}
public Feature Feature{get;set;}
}
Please refer the below links for the more information.
1) https://msdn.microsoft.com/en-us/library/jj591617(v=vs.113).aspx