Entity Framework: mapping tinyint to boolean

Question

by default Entity Framework maps tinyint to byte.

i tried changing the underlying type after it was generated to Boolean, but getting compilation error

Member Mapping specified is not valid. The type 'Edm.Boolean[Nullable=False,DefaultValue=]' of member blah...

is this possible in 4.0?

it wasn't my idea to use tinyint column as boolean. this was done automatically by another team using hibernate which apparently does it that way for mysql compatibility. obviously tinyint has more values than 2. I am looking for a way to map it so that anyting accept for 1 is false, or anything accept for 0 is true. either would work for me

is there a way to plug in a type translator of sorts into EF?

Answer 1

If your existing database has a tinyint column that you wish to represent as a Boolean property of your C# class, then you can do this as follows:

public class Subscription
{
  public int Id { get; set; }
  public string Name { get; set; }

  // the column of your database
  public byte? autoRenew { get; set; }

  // the property you want
  [NotMapped]
  public bool Autorenew
  {
    get => autoRenew > 0;
    set { this.autoRenew = (byte)(value ? 1 : 0);  }
  }
}

Obviously this assumes that 0 and 1 correspond to false and true, respectively. In this sample, the autoRenew is nullable and null is interpreted as false.

Answer 2

From MSDN's page on integer types, we see that the tinyint type represents an integer ranging from 0 to 255.

A bool, in contrast, represents only a binary 0 or 1.

Changing the default mapping from byte to bool (if it were even possible, which according to this page it seems like it's not) does not make sense -- how, for example, would you represent the value 42 (a valid tinyint) as a bool?

If you need an entity with a property of type bool, I'd suggest mapping it to a column of type bit.