I am trying to use the following form to enter new info into a database.

I am trying to use the entity framework.

I have the following classes of Interest:

public class InventoryContext : DbContext
{
    public DbSet<Item> Items { get; set; }

    ....Other DbSets follow...
}


[Table("Items")]
public class Item
{
    #region Strings
    public string Color { get; set; }
    public string FullName { get; set; }
    [Column(@"Sheet/Roll")]
    public string Type { get; set; }
    public string PrimaryMachine { get; set; }
    public string Alias { get; set; }
    public string Brand { get; set; }
    public string Finish { get; set; }

    #endregion

    #region Long
    public long ID { get; set; }
    public decimal? Weight { get; set; }
    #endregion

    #region Doubles
    public decimal? Size1 { get; set; }
    public decimal? Size2 { get; set; }
    public decimal? Size3 { get; set; }
    #endregion.
}

And I am stuck on filtering the dgvAllItems, based on the selected drop down values. I think my code is ugly and there is a better way.

    private void ComboBox_SelectedIndexChanged(object sender, EventArgs e)
    {

        ComboBox s = (ComboBox)sender;

        IQueryable<Item> query = c.Items;

        foreach (ComboBox cb2 in gbFilters.Controls.OfType<ComboBox>().Where(com => com.Text != ""))
        {
            string currentpropname = cb2.Name.Substring(2);

            if (cb2.Name.Substring(2, 4) == "Size" || cb2.Name == "cbWeight")
            {
                decimal? currentpropvalue = Convert.ToDecimal(cb2.Text);
                PropertyInfo propertyInfo = typeof(Item).GetProperty(currentpropname);
                ParameterExpression pe = Expression.Parameter(typeof(Item), "e");
                MemberExpression me = Expression.MakeMemberAccess(pe, propertyInfo);
                ConstantExpression ce = Expression.Constant(currentpropvalue, typeof(decimal?));
                BinaryExpression be = Expression.Equal(me, ce);

                Expression<Func<Item, bool>> lambda = Expression.Lambda<Func<Item, bool>>(be, pe);
                query = query.Where(lambda);
            }
            else
            {
                string currentpropvalue = cb2.Text;
                PropertyInfo propertyInfo = typeof(Item).GetProperty(currentpropname);
                ParameterExpression pe = Expression.Parameter(typeof(Item), "e");
                MemberExpression me = Expression.MakeMemberAccess(pe, propertyInfo);
                ConstantExpression ce = Expression.Constant(currentpropvalue, typeof(decimal?));
                BinaryExpression be = Expression.Equal(me, ce);

                Expression<Func<Item, bool>> lambda = Expression.Lambda<Func<Item, bool>>(be, pe);
                query = query.Where(lambda);
            }

        }

        bindingSource1.DataSource = query.ToList();
    }

    private void ComboBox_DropDown(object sender, EventArgs e)
    {
        ComboBox cb1 = (ComboBox)sender;

        IQueryable<Item> query = c.Items;

        foreach (ComboBox cb2 in gbFilters.Controls.OfType<ComboBox>().Where(com => com.Text != ""))
        {
            string currentpropname = cb2.Name.Substring(2);

            if (cb2.Name.Substring(2, 4) == "Size" || cb2.Name == "cbWeight")
            {
                decimal? currentpropvalue = Convert.ToDecimal(cb2.Text); 
                PropertyInfo propertyInfo = typeof(Item).GetProperty(currentpropname);
                ParameterExpression pe = Expression.Parameter(typeof(Item), "e");
                MemberExpression me = Expression.MakeMemberAccess(pe, propertyInfo);
                ConstantExpression ce = Expression.Constant(currentpropvalue, typeof(decimal?));
                BinaryExpression be = Expression.Equal(me, ce);

                Expression<Func<Item, bool>> lambda = Expression.Lambda<Func<Item, bool>>(be, pe);
                query = query.Where(lambda);
            }
            else
            {
                string currentpropvalue = cb2.Text;
                PropertyInfo propertyInfo = typeof(Item).GetProperty(currentpropname);
                ParameterExpression pe = Expression.Parameter(typeof(Item), "e");
                MemberExpression me = Expression.MakeMemberAccess(pe, propertyInfo);
                ConstantExpression ce = Expression.Constant(currentpropvalue, typeof(decimal?));
                BinaryExpression be = Expression.Equal(me, ce);

                Expression<Func<Item, bool>> lambda = Expression.Lambda<Func<Item, bool>>(be, pe);
                query = query.Where(lambda);
            }

        }

        string ActivePropName = cb1.Name.Substring(2);

        if (ActivePropName.Substring(0, 4) == "Size" || ActivePropName == "Weight")
        {

            ParameterExpression arg = Expression.Parameter(typeof(Item), "x");
            Expression expr = Expression.Property(arg, ActivePropName);
            LambdaExpression lambda = Expression.Lambda(expr, arg);
            Expression<Func<Item, decimal?>> expression = (Expression<Func<Item, decimal?>>)lambda;

            cb1.DataSource = query.Select(expression).Distinct().ToList();
        }
        else
        {
            ParameterExpression arg = Expression.Parameter(typeof(Item), "x");
            Expression expr = Expression.Property(arg, ActivePropName);
            LambdaExpression lambda = Expression.Lambda(expr, arg);
            Expression<Func<Item, string>> expression = (Expression<Func<Item, string>>)lambda;

            cb1.DataSource = query.Select(expression).Distinct().ToList();
        }
    }