Cannot clear dropdown fields

[teosarca]

Is this a bug or feature request?

Bug

What is the current behavior?

Which are the steps to reproduce?

• create a sales order
• add a sales order line
• advanced edit that order line
• try setting Packing Item field to "none".
  => ERROR because frontend is sending wrong patch value:

[{"op":"replace","path":"M_HU_PI_Item_Product_ID","value":{"key":"empty","caption":"none"}}]

Btw, for checking u can use any other draft order, or any other document where u have drop down which is not mandatory.

What is the expected or desired behavior?

it should be

[{"op":"replace","path":"M_HU_PI_Item_Product_ID","value":null}]

[teosarca]

issue introduced by #1327

[metas-dh]

Results of IT1
tested in mf15

• no error when setting Packing Item field to "none": OK

• after setting the Packing Item field to "none": in purchase order, you cannot select the original packing item again (works fine in sales order): => When filtering a view please use the newly introduced "/documentView/{windowId}/{viewId}/filter" endpoint #740
  => in sales order, after selecting the product in quick entry, you have to click tab to get to the quantity field, confirming the packing item too, whereas in purchase order, you get to the quantity field directly after selecting the product, no need to confirm the packing item there; might be related?