openerp-expert-production team mailing list archive

["Fabien \(Open ERP\)" <fp@xxxxxxxxxxx>]

I tend to agree with Antony, but I will try to explain why he
invalidates this discussion.

Introduction
----------------

OpenERP supports two costing methods: standard price and average price.

In average price, the cost price must be computed on the manufacturing
orders itself, based on raw materials and work orders. So, in that case
the cost price is updated at each transaction, based on the reallity. ->
I don't think this feature is already implemented in OpenERP.

In standard price, companies fix a price for each products, usually once
a year and the price usually do not change during this period. If you
change the price of a product, the law requires that you are able to
explain why and how you decided this new price.

These two methods are used to compute the Cost Price which reflects the
cost of the product (and also the inventory valuation). The cost of the
product reflects the average purchase price, the shipping costs, the raw
materials, the work orders, etc... Each company has it's own may to
compute a cost price. You can use specific rules if you are able to
proove an auditer why you used this valuation method.

Why what you required has been refused ?
--------------------------------------------------------

The problem is not that OpenERP does the multi-level computation or not.
The real bug here is that OpenERP should not update finished products if
you change the price of a raw material.

Why ?
  - some products have different BoM (but only one cost price)
  - some products have different ways to procure them (you can purchase or produce them)
  - some products's cost price are based on others rules than simply the sum of raw materials for the BoM (integrate
    border taxes or shipping in the cost, ...).
  - this would allow companies to enrich themselves very easily, which is not legal:
      * You have & stock of 1m€ of product A which is produced in a certain way
      * By the end of the year, you change the cost of the raw materials of the product A, now your stocks values 1.2m€
         even if you don't really did anything.
      * very useful, but not very legal :)

Some companies do not want side effects: you change one raw material
price -> all finnished products have their standard price updated. If
you do that, try to explain an accounting auditor how you value your
stock. This is very complex.

If the raw material are in average price and the finnished products are
in standard price, it means your finnished product's cost price is
updated at each transaction, which is not what you want for a standard
price.

The proposed solution
-----------------------------

In V5, it was clean. We have to make it again like in V5.

So, there is clearly a bug in OpenERP but it's not the one explained here but rather:
  - When we update a price or a BoM, standard prices of finnished products should not be updated. To do that, just
    remove the method do_change_standard_price in the line 57 in mrp/product.py

The best way to update your standard price for finnished products
(because once a year or periodically you want to do ittio for your stock
valuation computan) is to use the module we developed for v5:
product_extended. This module is not quality certified and I don't know
if it has been ported to v6 or not. That's why it's not covered by the
OPW and that's why antony said it's a missing feature, not a bug.

The product_extended module allows to decide, product per product if you
compute the cost price based on the BoM or not. If yes, you have buttons
in the product form (or an action on a whole list) that allows to
recompute the standard price on demand (usually once a year when you do
your stock valuation, and not when a raw material's price change). This
method is clean because you choose how and when you want to update cost
price per product and that's very important if your accounting is
audited.

What we will do
---------------------

Fix this bug: https://bugs.launchpad.net/openobject-addons/+bug/747056

As we have two OPW customers that reported this need we will develop the
product_extended module for v6, even if it's not covered by certified
modules.

I propose to keep this bug as invalid as the discussion at the top of
this bug may confuse the developers that will work on it. (unless I am
wrong, then we rediscuss)

-- 
You received this bug notification because you are a member of OpenERP
Manufacturing Experts, which is a direct subscriber.
https://bugs.launchpad.net/bugs/702288

Title:
  Cost price calculation limited to 2 levels in product bom

Status in OpenERP Modules (addons):
  Invalid

Bug description:
  A concrete example better than a long and difficult explanation :-)

  We have the following product A composed of the product B and product B is composed from product C. So the below BOM:
  A
  -----B
  -----------C

  If the price of B is modified, then the price of A can be also modified.
  But if i modify the price of C, only B is modified and not A.

  This is a very important blocking issue, since in most of the real prod environment, we've of course more than 2 level of boms (in some customer installation, up to 100 levels !).
  So any modification at the bottom should have a consequence on all the bom structure until the top, else OpenERP cannot be used for production.