Hi!

In Posting of CashPurchase I am trying to write an attribute value of the catalog 'products'.

Product = Catalogs.Products;
CatalogSelection = Product.Select(CurRowLineItems.Product);
Object = CatalogSelection.GetObject();
Object.ListPriceSupplier = 1; // here 1 is just for testing

Hi!

Try using this code:

Object = CurRowLineItems.Product.GetObject();
Object.ListPriceSupplier = 1; // here 1 is just for testing 

Thanks, Alexey! It does work. But what could be another solution? Actually I need MainSupplier (Vendor). And it should be changed when posting of the document. Do you have some another idea?

If you are changing contacts, for example, you need to store contacts inside the document and add a button which performs saving these values to the selected product.
If you want to keep the number of documents where this product was used, or something like that, you can add an information register where this data will be stored.