[ADD] inventory: valuation by lots

closes odoo/documentation#11138

Signed-off-by: Samuel Lieber (sali) <sali@odoo.com>

content/applications/inventory_and_mrp/inventory/product_management/inventory_valuation.rst

@@ -10,3 +10,4 @@ Inventory valuation
    inventory_valuation/inventory_valuation_config
    inventory_valuation/using_inventory_valuation
    inventory_valuation/integrating_landed_costs
+   inventory_valuation/valuation_by_lots

content/applications/inventory_and_mrp/inventory/product_management/inventory_valuation/using_inventory_valuation.rst

@@ -108,6 +108,8 @@ available during a prior specified date can be seen and selected.
    the teal :guilabel:`➡️ (right arrow)` button to the right of the :guilabel:`Reference` column
    value.
 
+.. _inventory/product_management/update-unit-price:
+
 Update product unit price
 -------------------------
 

content/applications/inventory_and_mrp/inventory/product_management/inventory_valuation/valuation_by_lots.rst

@@ -0,0 +1,208 @@
+================================
+Valuation by lots/serial numbers
+================================
+
+Track :doc:`inventory valuation <using_inventory_valuation>` by :doc:`lots or serial numbers
+<../../product_management/product_tracking>` to:
+
+#. :ref:`Compare and differentiate purchasing cost <inventory/product_management/view-valuation>`,
+   based on lot or serial numbers.
+#. Track the actual cost of manufactured products, based on the real cost of each tracked component
+   used.
+#. Depreciate specific lot or serial numbers when they :doc:`sit in stock for too long
+   <../../warehouses_storage/reporting/aging>`.
+
+.. important::
+   Please read this :doc:`introduction to inventory valuation <inventory_valuation_config>` before
+   setting up valuation by lot/serial numbers.
+
+Configuration
+=============
+
+To enable valuation by lots or serial numbers, begin by enabling the :doc:`Lots and Serial Numbers
+feature <../product_tracking>`. After that, go to :menuselection:`Inventory app --> Products -->
+Products`, and select the desired product, or create a new product, by clicking :guilabel:`New`.
+
+On the product form, in the :guilabel:`Category` field, choose a product category. Ensure the
+product category's :ref:`Costing Method <inventory/warehouses_storage/costing_methods>` is set to
+*First In First Out (FIFO)* or *Average Cost (AVCO)*.
+
+.. tip::
+   To check the costing method set on the product category, hover over the :guilabel:`Category`
+   field, and click the :icon:`oi-arrow-right` :guilabel:`(Internal Link)` icon.
+
+.. seealso::
+   :ref:`Costing methods <inventory/warehouses_storage/costing_methods>`
+
+Next, activate the product to be tracked by lots or serial numbers by ticking the :guilabel:`Track
+Inventory` checkbox. Then, click the adjacent field that appears, and choose either :guilabel:`By
+Lots` or :guilabel:`By Unique Serial Number` from the resulting drop-down menu.
+
+Doing so makes the :guilabel:`Valuation by Lot/Serial number` checkbox appear below it. Tick that
+checkbox, and the configuration to track valuation by lot or serial numbers is complete.
+
+.. figure:: valuation_by_lots/product-form.png
+   :alt: Product form showing the Valuation by Lot or Serial Number feature.
+
+   Product form showing the Valuation by Lot or Serial Number feature
+
+Valuation layers
+================
+
+To understand how valuation by lots and serial numbers works, consider these scenarios:
+
+#. :ref:`Purchase and sell products <inventory/product_management/valuation-cost-example>`: cost is
+   calculated based on the *product category's* costing method.
+#. :ref:`Create new lot/serial numbers <inventory/product_management/valuation-cost-new>` using an
+   inventory adjustment: value of the new lot/serial number is assigned to the cost from the product
+   form.
+#. Inventory adjustment to update quantities for an :ref:`existing lot/serial number
+   <inventory/product_management/valuation-cost-existing>`: value is assigned based on the most
+   recent cost for that lot/serial number.
+
+For both :abbr:`AVCO (Average Cost)` and :abbr:`FIFO (First In First Out)` methods, the *Cost* field
+on the product form is calculated using this formula:
+
+:math:`Avg~Cost = \frac{Total~Value}{Total~Qty}`
+
+.. _inventory/product_management/valuation-cost-example:
+
+Purchase products
+-----------------
+
+Consider how purchasing products affect the inventory valuation, in the table below.
+
+.. list-table::
+   :header-rows: 1
+   :stub-columns: 1
+
+   * -
+     - Quantity
+     - Lot number
+     - Math
+     - Average cost on product form
+   * - Empty stock
+     - 0.00
+     -
+     -
+     - $0
+   * - Day 1: Receive one product at $10/unit
+     - 1.00
+     - LOT 1
+     - :math:`\frac{10}{1}`
+     - $10
+   * - Day 2: Receive another product at $20/unit
+     - 1.00
+     - LOT 2
+     - :math:`\frac{10+20}{2}`
+     - $15
+
+.. figure:: valuation_by_lots/lip-gloss.png
+   :alt: Show Cost on the product form.
+
+   As a result, the product form displays an average cost of $15 in the **Cost** field.
+
+.. _inventory/product_management/valuation-cost-new:
+
+Create new lot/serial number
+----------------------------
+
+Creating a new lot/serial number through an :doc:`inventory adjustment
+<../../warehouses_storage/inventory_management/count_products>` assigns the same value as the cost
+on the product form.
+
+To make an inventory adjustment, and assign a lot number, go to :menuselection:`Inventory app -->
+Operations --> Physical Inventory`. Then, click :guilabel:`New`.
+
+In the new inventory adjustment line that appears, set the :guilabel:`Product`, create the
+:guilabel:`Lot/Serial Number`, set the :guilabel:`Counted Quantity`, and click :icon:`fa-floppy-o`
+:guilabel:`Apply`.
+
+To view the valuation layer, go to :menuselection:`Inventory app --> Reporting --> Valuation`. The
+:guilabel:`Total Value` per unit matches the *Cost* on the product form.
+
+.. example::
+   Continuing the example in the table above, when the product cost is `$15`, the valuation for a
+   newly-created `LOT3` is also be `$15`.
+
+   .. image:: valuation_by_lots/create-new.png
+      :alt: Show inventory adjustment valuation.
+
+.. _inventory/product_management/valuation-cost-existing:
+
+Existing lot/serial number
+--------------------------
+
+When adjusting the quantity of an existing lot/serial number, the value is based on the most recent
+valuation layer for that specific lot/serial number.
+
+.. example::
+   Continuing the example in the table above, the value for `LOT 1` is `$10`.
+
+   So, when the quantity is updated from `1.00` to `2.00`, the additional quantity is also valued at
+   `$10`, reflecting the latest valuation layer for `LOT 1`.
+
+   .. figure:: valuation_by_lots/existing.png
+      :alt: Show valuation of LOT 1 getting updated.
+
+      The inventory adjustment (top line) is valued the same as LOT 1 (bottom line).
+
+.. _inventory/product_management/view-valuation:
+
+View valuation
+==============
+
+To find the average cost of a specific lot/serial number, go to :menuselection:`Inventory app -->
+Products --> Lots/Serial Numbers`, and select the desired record.
+
+Both the :guilabel:`Cost` and :guilabel:`Average Cost` fields show a unit's average cost. The
+:guilabel:`Total Value` reflects the total on-hand value for that lot/serial number.
+
+.. important::
+   Ensure the costing method is set to *First In First Out (FIFO)* or *Average Cost (AVCO)* to
+   display the cost on this page.
+
+.. figure:: valuation_by_lots/lot.png
+   :alt: Show cost of the lot/serial number.
+
+   Lot form, displaying **Cost** field. The **Valuation** smart button is in the top-right.
+
+Valuation layers of a lot/serial number can be viewed through the :ref:`valuation report
+<inventory/product_management/valuation-report>`, or by clicking the lot/serial number's
+:guilabel:`Valuation` smart button. These detailed, line-by-line records can help determine how each
+inventory move of the specific lot/serial number affects its valuation.
+
+.. _inventory/product_management/valuation-report:
+
+Valuation report
+----------------
+
+Display the valuation of lots and serial numbers in the database by going to
+:menuselection:`Inventory app --> Reporting --> Valuation`.
+
+On the resulting :guilabel:`Stock Valuation` report, click the search bar, and in the
+:icon:`oi-group` :guilabel:`Group By` section of the resulting drop-down menu, select
+:guilabel:`Lot/Serial number`.
+
+.. tip::
+   Click the :icon:`fa-plus` :guilabel:`(plus)` icon to the right of a collapsed lot number line to
+   :ref:`manually modify the cost <inventory/product_management/update-unit-price>`.
+
+   This is useful for adjusting individual lot prices when a purchase order or bill includes
+   multiple lots/serial numbers, as initial prices are identical upon reception.
+
+.. image:: valuation_by_lots/stock-valuation.png
+   :alt: Show valuation report, by lots.
+
+Valuation smart button
+----------------------
+
+To access a filtered part of the *Stock Valuation* report, specific to a lot or serial number, go to
+:menuselection:`Inventory app --> Products --> Lots/Serial Numbers`, and select the desired item.
+
+On the :guilabel:`Lot/Serial Numbers` page, click the :guilabel:`Valuation` smart button.
+
+.. figure:: valuation_by_lots/lot-stock-valuation.png
+   :alt: All stock moves relating to `LOT 1`.
+
+   All stock moves that affect the valuation of `LOT 1`.