Include

using System.Linq.Expressions;
using System.Collections.Generic;

namespace System.Data.Objects
{
    public static class SilverExtensions
    {
        public static ObjectQuery<T> Include<T, T2>(this ObjectQuery<T> data, Expression<Func<T, ICollection<T2>>> property1, Expression<Func<T2, object>> property2)
            where T : class
            where T2 : class
        {
            var name1 = (property1.Body as MemberExpression).Member.Name;
            var name2 = (property2.Body as MemberExpression).Member.Name;

            return data.Include(name1 + "." + name2);
        }
        
        public static ObjectQuery<T> Include<T, T2>(this ObjectQuery<T> data, Expression<Func<T, T2>> property1, Expression<Func<T2, object>> property2) where T : class
        {
            var name1 = (property1.Body as MemberExpression).Member.Name;
            var name2 = (property2.Body as MemberExpression).Member.Name;

            return data.Include(name1 + "." + name2);
        }

        public static ObjectQuery<T> Include<T>(this ObjectQuery<T> data, Expression<Func<T, object>> property) where T : class
        {
            var name = (property.Body as MemberExpression).Member.Name;

            return data.Include(name);
        }
    }
}
Example:
Instead of writing:
ObjectContext.Employee.Include("Address").Include("Department.Division");

one can now use a completely type-safe variant:
ObjectContext.Employee.Include(x=>x.Address).Include(y=>y.Department, z=>z.Division);

This finally gets rid of that nasty piece of untyping in an otherwise lovely type-safe system... 

Description

Type-safe Include: a completely type-safe way to include nested objects in scenarios with DomainServices and RIA in, for example, Silverlight applications. Example: Include(x=>x.Parent) instead of Include("Parent"). A more detailed explanation can be found at http://www.chrismeijers.com/post/Type-safe-Include-for-RIA-DomainServices.aspx

Details

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