The entity type 'Program' requires a primary key to be defined - entity-framework

Question

I am trying to make a simple website that tracks students, programs, and classes. I've created the entities and I'm getting an error when trying to add the migration.
"The entity type 'Program' requires a primary key to be defined."
I have tried using the [Key] attribute and there is an Id field. The other table was created just fine. What else should I try?
Here is the problem class:
public class Program
{
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public bool UseRanks { get; set; }
}
Here is another table that I had no problems creating a migration for:
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string CellPhone { get; set; }
public string HomePhone { get; set; }
public string WorkPhone { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string State { get; set; }
public string ZipCode { get; set; }
public DateTime BirthDate { get; set; }
}
Here is what is in my ApplicationDbContext class:
public class ApplicationDbContext : IdentityDbContext
{
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
: base(options)
{
}
//public DbSet<Attendance> Attendances { get; set; }
public DbSet<Person> People { get; set; }
public DbSet<Bill> Bills { get; set; }
//public DbSet<Session> Sessions { get; set; }
public DbSet<Program> Programs { get; set; }
}
I've commented out the other entities because I was trying to add them one at a time. Trying to add a migration with all the entities resulted in the same error with the same specific class.

Answer 1

Complete shot in the dark, but based on the name of this class, I'm guessing you're referencing the wrong Program. Make sure that your DbSet<Program> is actually using your Program entity and not something like the Program class used at the console app level. You'll likely need to explicitly use the namespace, i.e. DbSet<MyApp.Models.Program>.
You might also consider changing the name of the class to remove any chance of ambiguity. There's some class names that are just going to wreck havoc trying to use them because they'll conflict with framework stuff constantly. It's usually more hassle than it's worth just to have that particular name. Program is one of those.

Answer 2

You can try to use this way:
public class Program
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public bool UseRanks { get; set; }
}
Adding [Key] attribute to the Id property.
In the file ApplicationDbContext.cs, you can override OnModelCreating method:
public DbSet<Program> Programs { get; set; }
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<Program>().ToTable("Programs").HasKey(x => x.Id);
}