CheckNull code for C# Expressions.

CheckNull.cs

public static Expression<Func<T, T>> CheckNull<T>(Expression<Func<T, T>> expression)
{
	var body = expression.Body as MemberInitExpression;
	return Expression.Lambda<Func<T, T>>(AddCheckNull<T>(body, expression.Parameters[0]), expression.Parameters);
}

public static MemberInitExpression AddCheckNull<T>(MemberInitExpression expression, Expression parameter)
{
	var memberParams = new List<MemberBinding>();
	foreach (var item in expression.Bindings)
	{
		var assignment = (item as MemberAssignment);
		if (assignment.Expression is MemberInitExpression)
		{
			memberParams.Add(AddCheckNull<T>(item, assignment.Member as PropertyInfo, parameter));
		}
		else
		{
			memberParams.Add(item);
		}
	}
	return Expression.MemberInit(expression.NewExpression, memberParams.ToArray());

}

public static MemberBinding AddCheckNull<T>(MemberBinding binding, PropertyInfo property, Expression parameter)
{
	var assignment = binding as MemberAssignment;
	var propertyExpression = Expression.Property(parameter, property);
	if (assignment.Expression is MemberInitExpression)
	{
		return assignment.Update(Expression.Condition(Expression.NotEqual(propertyExpression, Expression.Constant(null, property.PropertyType)), AddCheckNull<T>(assignment.Expression as MemberInitExpression, propertyExpression), Expression.Constant(null, property.PropertyType)));
	}
	else
	{
		return assignment.Update(Expression.Condition(Expression.NotEqual(propertyExpression, Expression.Constant(null, property.PropertyType)), assignment.Expression, Expression.Constant(null, property.PropertyType)));
	}
}