Entity Framework Code First Casting Columns

问题

I have an class

public class Foo
{
    public int UserId { get; set; }
}

and I'm using the code first fluent mapping to map this to the database.

Property(i => i.UserId)
            .HasColumnName("userno");

the only problem is that userno is actually a char(10) in the database. How do I go about casting or converting this type? as I currently get this error.

The 'UserId' property on 'Foo' could not be set to a 'String' value. You must set this property to a non-null value of type 'Int32'.

Thanks

回答1:

Entity framework doesn't have any support for type conversion in mapping so the only valid mapped property in your scenario is:

public class Foo
{
    public string UserId { get; set; }
}

If you want int property as well you must do:

public class Foo
{
    public string UserId { get; set; }

    public int UserIntId 
    {
       get { return Int32.Parse(UserId); }
       set { UserId = value.ToString(); }
    }
}

And add this to your mapping:

Ignore(i => i.UserIntId);

You can play with accessibility of UserId property but be aware that accessibility also affects if your mapping actually sees the property. If it doesn't you will not have UserId mapped at all.

来源：https://stackoverflow.com/questions/6909309/entity-framework-code-first-casting-columns