EF 6 Codefirst -Setting default value for a property defined in base class using fluent API

Question

I have a base class which has audit properties like

public abstract class BaseModel
{
    [Column(Order = 1)] 
    public long Id { get; set; }
    public long CreatedBy { get; set; }
    public DateTime CreatedDate { get; set; }
    public long ModifiedBy { get; set; }
    public DateTime ModifiedDate { get; set; }
    public bool IsActive { get; set; }
}

All my poco classes derive from this class.

I am trying to set a default value to the IsActive properties. I am not keen on using annotations and hence was wandering if I can work this using fluent API.

I tried this but it does not work. Seems like it creates a new table named BaseModel

modelBuilder.Entity<BaseModel>()
    .Property(p => p.IsActive)
    .HasColumnAnnotation("DefaultValue", true);

Can any one suggest a way here?

Answer 1

There is no way to do this. It can't set default values with Entity Framework. Instead you can use the constructor

public abstract class BaseModel
{
    protected BaseModel()
    {
        IsActive = true;
    }
}

Answer 2

I have resolved this problem by overriding the SaveChanges method. See below for my solution.

1. Solution Explain

   i) Override the SaveChanges method in the DbContext class.

   public override int SaveChanges()
   {
       return base.SaveChanges();
   }
   

   ii) Write logic to set default values

   public override int SaveChanges()
   {
       //set default value for your property
       foreach (var entry in ChangeTracker.Entries().Where(entry => entry.Entity.GetType().GetProperty("YOUR_PROPERTY") != null))
       {
           if (entry.State == EntityState.Added)
           {
               if (entry.Property("YOUR_PROPERTY").CurrentValue == null)
                   entry.Property("YOUR_PROPERTY").CurrentValue = YOUR_DEFAULT_VALUE;
           }
       }
   
       return base.SaveChanges();
   }
   

2. Example

   i) Create Base Class

     public abstract class BaseModel
     {
          [Column(Order = 1)] 
          public long Id { get; set; }
          public long CreatedBy { get; set; }
          public DateTime CreatedDate { get; set; }
          public long ModifiedBy { get; set; }
          public DateTime ModifiedDate { get; set; }
          public bool IsActive { get; set; }
     }
   

   ii) override SaveChanges

   public override int SaveChanges()
   {
   
       //set default value for IsActive property
       foreach (var entry in ChangeTracker.Entries().Where(entry => entry.Entity.GetType().GetProperty("IsActive") != null))
       {
           if (entry.State == EntityState.Added)
           {
               if(entry.Property("IsActive").CurrentValue == null)
                   entry.Property("IsActive").CurrentValue = false;
           }
       }
   
       return base.SaveChanges();
   }