Entity Framework 6 Code First - Custom Type Mapping

Question

I'm using some models inside my domain which are not very serialization- or mapping-friendly, such as structs or classes from the System.Net.* namespace.

Now I'm wondering if it's possible to define custom type mappings in Entity Framework.

Pseudo:

public class PhysicalAddressMap : ComplexType<PhysicalAddress>() {
    public PhysicalAddressMap() {

        this.Map(x => new { x.ToString(":") });
        this.From(x => PhysicalAddress.Parse(x));
    }
}

Desired result:

SomeEntityId       SomeProp         PhysicalAddress    SomeProp
------------------------------------------------------------------
           4          blubb       00:00:00:C0:FF:EE        blah

                                           ^
                                           |
                             // PhysicalAddress got mapped as "string"
                             // and will be retrieved by
                             // PhysicalAddress.Parse(string value)

Latia

Answer 1

wrap a NotMapped property of type PhysicalAddress with a mapped string property that handles the conversions:

    [Column("PhysicalAddress")]
    [MaxLength(17)]
    public string PhysicalAddressString
    {
        get
        {
            return PhysicalAddress.ToString();
        }
        set
        {
            PhysicalAddress = System.Net.NetworkInformation.PhysicalAddress.Parse( value );
        }
    }

    [NotMapped]
    public System.Net.NetworkInformation.PhysicalAddress PhysicalAddress
    {
        get;
        set;
    }

Update: example code for comment asking about wrapping functionality in a class

[ComplexType]
public class WrappedPhysicalAddress
{
    [MaxLength( 17 )]
    public string PhysicalAddressString
    {
        get
        {
            return PhysicalAddress == null ? null : PhysicalAddress.ToString();
        }
        set
        {
            PhysicalAddress = value == null ? null : System.Net.NetworkInformation.PhysicalAddress.Parse( value );
        }
    }

    [NotMapped]
    public System.Net.NetworkInformation.PhysicalAddress PhysicalAddress
    {
        get;
        set;
    }

    public static implicit operator string( WrappedPhysicalAddress target )
    {
        return target.ToString();
    }

    public static implicit operator System.Net.NetworkInformation.PhysicalAddress( WrappedPhysicalAddress target )
    {
        return target.PhysicalAddress;
    }

    public static implicit operator WrappedPhysicalAddress( string target )
    {
        return new WrappedPhysicalAddress() 
        { 
            PhysicalAddressString = target 
        };
    }

    public static implicit operator WrappedPhysicalAddress( System.Net.NetworkInformation.PhysicalAddress target )
    {
        return new WrappedPhysicalAddress()
        {
            PhysicalAddress = target
        };
    }

    public override string ToString()
    {
        return PhysicalAddressString;
    }
}

Latham

Is there any way to wrap this behaviour in a class to reuse it? – Alden

Sure - create a complex type with relevant conversion operators. Added example code to solution. – Latham

Ok, thanks. The problem I'm having right now is that I can't rename database columns because of backwards compatibility, so I'd want to map to a custom column each properties of type WrappedPhysicalAddress – Alden

With attributes? (I don't like the fluent api) – Alden

Yes and no - you can define the default column names with attributes, but if you want to change column names when used in a specific entity, you will need to use the fluent API. Try testing it out yourself next time. – Latham

I've spent hours testing different possibilities. I'm asking to get answers to whether EF supports something like that. – Alden

Does not support almost any EF Expression Tree. – Valuer