Entering keys manually with Entity Framework

Question

I'm trying to use Entity Framework code first for a simple database project and I run into a problem I simply cannot figure out.

I noticed EF was setting the ID for my tables automatically increasing by 1 each time, completely ignoring the value I entered manually for that field. After some searching it is my understanding that the right way to disable this behavior is doing:

modelBuilder.Entity<Event>().Property(e => e.EventID).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

However now I'm just getting this error and I have no idea why:

Unhandled Exception: System.Data.Entity.Infrastructure.DbUpdateException: An error occurred while updating the entries. See the inner exception for details. ---

System.Data.UpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: Cannot insert explicit value for identity column in table 'Events' when IDENTITY_INSERT is set to OFF.

If it's helpful, here is the POCO class in question:

public class Event
{
    [Key, Required]
    public int EventID { get; set; }

    public string EventType { get; set; } //TODO: Event Type Table later on
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }

    public virtual ICollection<Match> Matches { get; set; }
    public virtual ICollection<EventParticipation> EventParticipation { get; set; }
}

Thanks in advance.

Answer 1

Since I prefer attributes, here the alternative for the sake of completeness:

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int Id { get; set; }

Note: This works also in EF Core.