Product quantity not saved when EAV cache enabled - Magento 2

Question

When I'm trying to change the quantity of a product in the admin, it will not be stored in the database. This problem only occurs when the EAV cache is enabled.

The quantity input field has the name: "product[quantity_and_stock_status][qty]". If I save the product, javascript will create a new hidden input field with the name "product[stock_data][qty]". After saving the product, there will be a page refresh. After that page refresh, there is a POST request visible in the Network tab from my Chrome Developer Tools.

When I check the Request Payload in the tab Headers, both input field values are visible, I see the quantity_and_stock_status:

    Content-Disposition: form-data; name="product[quantity_and_stock_status][qty]"
    1700

And I see the stock_data:

    Content-Disposition: form-data; name="product[stock_data][qty]"
    1500

1700 is the value that I entered in the quantity field, but the value didn't change in the database, so it sets the old value (1500) in the input field:

When I check the page source (after the page was saved), the JSON of the product form data contains quantity_and_stock_status and stock_data. But now the values are both 1500.

"product_form_data_source": {
  "type": "dataSource",
  "name": "product_form_data_source",
  "dataScope": "product_form",
  "config": {
    "data": {
      "product": {
        "status": "1",
        "name": "Target Power Star Air G3 Black",
        "sku": "330800",
        "price": "1.07",
        "tax_class_id": "4",
        "quantity_and_stock_status": {
          "is_in_stock": 1,
          "qty": 1500
        },
        "attribute_set_id": "11",
        "current_product_id": "1878",
        "stock_data": {
          "item_id": "1868",
          "product_id": "1878",
          "stock_id": "1",
          "qty": 1500,
          "min_qty": 0,
          "use_config_min_qty": "1",
          "is_qty_decimal": 0,
          "backorders": 2,
          "use_config_backorders": "1",
          "min_sale_qty": 1,
          "use_config_min_sale_qty": "1",
          "max_sale_qty": 10000,
          "use_config_max_sale_qty": "1",
          "is_in_stock": 1,
          "low_stock_date": null,
          "notify_stock_qty": 1,
          "use_config_notify_stock_qty": "1",
          "manage_stock": 1,
          "use_config_manage_stock": "1",
          "stock_status_changed_auto": "0",
          "use_config_qty_increments": "1",
          "qty_increments": 0,
          "use_config_enable_qty_inc": "1",
          "enable_qty_increments": 0,
          "is_decimal_divided": 0,
          "website_id": "0",
          "type_id": "simple",
          "min_qty_allowed_in_shopping_cart": "1"
        }
      }
    }
  }
}

(This is only the relevant info of the JSON)

Has anyone encountered this problem or could this be a Magento bug?

Answer 1

If you fetch issue with your new product type then simply make change in product_types.xml.

open product_types.xml and add to node type attribute isQty="true. e.g

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../Magento/Catalog/etc/product_types.xsd">
    <type name="yournewproducttype" label="New Product Type" modelInstance="[NameSpace]\[Module]\Model\Product\Type\Credit" indexPriority="10" isQty="true" canUseQtyDecimals="false" sortOrder="25">
        <priceModel instance="[NameSpace]\[Module]\Model\Product\Type\Credit\Price" />
    </type>
    <composableTypes>
        <type name="yournewproducttype" />
    </composableTypes>
</config>

Hope so it's help you !!

Answer 2

I have the same problem. It seems to only happen on my custom product type but so far I haven't found a solution. Unless the product type doesn't have all the needed product attributes assigned to it.