In Entity Framework 7 which property Attribute creates an index in code first?

data-annotations entity-framework-core

Question

In Entity Framework 7 (7.0.0-rc1-final) which property Attribute creates an index?

I would normally add an index to a sql table to improve look up times so I assume I need to specify this in my class?

public class Account
{
  [Key]
  [Required]
  public int AccountId { get; set; }

  [Required] <-- How do I make this an Index in Sql Server?
  public int ApplicationUserId { get; set; }
}

I assume [Index] would do it but this is not recognised.

How do I index the ApplicationUserId column?

Accepted Answer

Use the fluent API in your DbContext class:

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Account>()
            .HasIndex(b => b.ApplicationUserId);
    }

Popular Answer

Here is a workaround:

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
    public class IndexAttribute : Attribute
    {
    }

protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
foreach (var entity in modelBuilder.Model.GetEntityTypes())
            {
                foreach (var property in entity.GetProperties())
                {
                    if (property.PropertyInfo != null && property.PropertyInfo.GetCustomAttributes<IndexAttribute>().Any())
                    {
                        entity.AddIndex(new[] { property });
                    }
                }
            }
    }


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