Generic Entity Framework mapping

Question

To beginning I'm novice with Expression and Func.

I'm trying to avoid duplicate code in my EF mapping class, and I'm stuck with bad database.

Take the following example map class:

public class EntityMap : EntityTypeConfiguration<Entity>
{
    public EntityMap()
    {
        Property(x => x.PropertyA.Property);
        Property(x => x.PropertyB.Property);
    }
}

Where PropertyA and PropertyB are same type, and with many property Is it possible to refactor this with a simple method, pass x => x.PropertyA or PropertyB in parameters and do something like Property(x => x. methodParemeter Property); ? And how ? The method could be something like that:

private void SubMap(Expression<Func<Entity, SubEntity>> propertyExpression, string prefix)
{
    Property(x => x.propertyExpression.Property)
            .HasColumnName(string.Format("{0}{1}", prefix,"columnName"));
}

Answer 1

You could do with with a base class and an interface.

Models

public interface IEntity
{
    string PropertyA { get; set; }
    string PropertyB { get; set; }
}

public class EntityA : IEntity {
    public string PropertyA { get; set; }
    public string PropertyB { get; set; }
}

public class EntityB : IEntity
{
    public string PropertyA { get; set; }
    public string PropertyB { get; set; }
}

Base class

public abstract class IEntityMap<T> : EntityTypeConfiguration<T> where T : class, IEntity
{
    protected IEntityMap()
    {
        this.Property(x => x.PropertyA);
        this.Property(x => x.PropertyB);
    }
}

Mapper Implementations

Register these with your DbContext type.

public class EntityAMap : IEntityMap<EntityA>
{
    public EntityAMap() : base()
    {
    }
}

public class EntityBMap : IEntityMap<EntityB>
{
    public EntityBMap() : base()
    {
    }
}