Question

For example I have a list called Product and it has 3 columns, ProductName (which is the Title), ProductPrice and ProductType.

• ProductName is a string
• ProductPrice is a currency (double)
• ProductType is a LookUp on ProductTypes List

Normally this is easy for me if it does not contain a LookUp column, but I dont know how to deal with look up columns when Inserting.

I had tried this one but it returns an error Specified cast is not valid.

Here is the current code

EntityList<ProductTypeItem> ProductTypes = dc.GetList<ProductTypeItem>("ProductType");

ProductItem newProduct = new ProductItem();

newProduct.Title = txtProductName.Text;
newProduct.ProductPrice = double.Parse(txtProductPrice.Text); 
newProduct.ProductType = (from a in ProductTypes where a.Title == ddProductType.SelectedItem.Text select a).FirstOrDefault();

dc.Product.InsertOnSubmit(newProduct);
dc.SubmitChanges();   

What would I do with the newProduct.ProductType as here is where the error occurs.

Please note that the ddProductType DataSource is the ProductType List and uses Title in its DataTextField and DataValueField

Answer 1

It works now and here is the solution

EntityList<Item> ProductTypes = dc.GetList<Item>("ProductType");
Item oProductType = (from a in ProductTypes where a.Title == ddProductType.SelectedItem.Text select a).FirstOrDefault();
ProductItem newProduct = new ProductItem();

newProduct.Title = txtProductName.Text;
newProduct.ProductPrice = double.Parse(txtProductPrice.Text);
newProduct.ProductType = (ProductTypeItem)oProductType;

dc.Product.InsertOnSubmit(newProduct);
dc.SubmitChanges();   

The only thing I changed is to initialize the the Product Type as Item rather than ProductTypeItem, then cast it to ProductTypeItem now it works