Hi,

You can use sequence for this purpose. Here is more details.

First you have to define "sequence type" and "sequence" as follows in xml file (better define a new xml file for sequence) :-

<openerp>

<data noupdate="1">

<!-- Sequences for purchase.order -->

<record id="seq_type_brand" model="ir.sequence.type">

<field name="name">Brand</field>

<field name="code">product.brand</field> # name of type

</record>

<record id="seq_brand" model="ir.sequence">

<field name="name">Brand</field>

<field name="code">product.brand</field> # name of type

<field name="padding">5</field>

<field name="number_next">50000</field> # first number

<field name="number_increment">1</field> # increment by

</record>

</data>

</openerp>

->here in "ir.sequence" you can use attribute like 'prefix' and 'suffix' if needed (number_next is starting number)

Then you can use get method (of ir.sequence) in defaults of field you want to generate sequence :-

Eg : test = fields.Char('Test', default = lambda obj: obj.env['ir.sequence'].get('product.brand') or '/') 

or if you want to only generate the sequence when a record is saved, you can override the create function.

Hope this helps........