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Fields definitions parameter change_default?

on 2/12/16, 8:32 AM 2,997 views

I have not found any documentation on the parameter change_default. Can anyone knows its meaning?

Example from sale.py:

'product_id': fields.many2one('product.product', 'Product', domain=[('sale_ok', '=', True)], change_default=True, readonly=True, states={'draft': [('readonly', False)]}, ondelete='restrict'),


Jérémy Kersten (jke)

--Jérémy Kersten (jke)--

| 3 3 5
Jodoigne, Belgium
--Jérémy Kersten (jke)--

Jérémy is a member of the core R&D team since september 2013. He developed several projects for OpenERP version 8 including the eCommerce, the Google Calendar synchronization and the new product variants/configurator. Now, he manages Odoo website and themes for saas.

Jérémy Kersten (jke)
On 2/13/16, 4:46 PM


A example will maybe help you...

Take a model with a field A, and a field B.  

The field B has change_default set to True.

Now, if you go to the form view in debug mode and set a default value for the field A. You can set this value depending on the value of B...

Thank you very much for this helpful picture and answer. Now I understand :)

on 2/14/16, 3:30 AM

Axel Mendoza

--Axel Mendoza--
| 7 8 8
Camaguey, Cuba
--Axel Mendoza--

DevOps - Full stack - Software Architect - Developer - Technology Integrator

I could help you to develop anything and solve complex problems based on technologies, integrations and tricky stuffs mostly in Python with OpenERP/Odoo, Zato, Django and many others frameworks programming languages and technologies.

I offers consulting services to anyone with an unanswered questions or needs for customizations. Think about it, maybe it's better to have an expert to solve your issues and projects than having a full-time employee trying to understand what to do and how

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Axel Mendoza
On 2/12/16, 11:21 AM

Well I haven't see the answer of @jke before find mine and I think that this question haven't had an answer. That's a way to use it. I will write my own version that could help developers more and also is more technical to express value change rules by xml ir.values record. I don't mean that @jke answer is incorrect. Just that these are the technical insides.

The other way is by writing ir.values records with type='default' and key2='field_with_change_default=value' for the model in question. It will cause that the name and value of those ir.values records that match the key2 value condition will be used as a result of the change of the field_with_change_default. As example you could use the field zip of the res.partner model that has defined with change_default=True. Writing some records like this:

<record model="ir.values" id="partner_zip_name">
<field name="name">name</field>
<field name="value">Axel</field>
<field name="key">default</field>
<field name="key2">zip=5000</field>
<field name="model">res.partner</field>
<record model="ir.values" id="partner_zip_phone">
<field name="name">phone</field>
<field name="value">+99999999</field>
<field name="key">default</field>
<field name="key2">zip=5000</field>
<field name="model">res.partner</field>

Will cause that when the zip code in a partner is set to 5000 the name will be changed to 'Axel' and the phone will be changed to '+99999999' like if you have an onchange to return those values and also this could rewrite an existing value returned by an onchange execution that get executed before the code responsible for this, runs. Here is the js code that allow this behavior for references. 

if (field && field.change_default) {

var value_;

if (response.value && (fieldname in response.value)) {

// Use value from onchange if onchange executed

value_ = response.value[fieldname];

} else {

// otherwise get form value for field

value_ = self.fields[fieldname].get_value();


var condition = fieldname + '=' + value_;

if (value_) {

defs.push(self.alive(new instance.web.Model('ir.values').call(

'get_defaults', [self.model, condition]

)).then(function (results) {

if (!results.length) {

return response;


if (!response.value) {

response.value = {};


for(var i=0; i<results.length; ++i) {

// [whatever, key, value]

var triplet = results[i];

response.value[triplet[1]] = triplet[2];


return response;




It is actual in new api? My api@onchange are tirggered without this parameters (with change_default = False)? In old api I did never use this parameter too, but on_change works? I think I do not understand :(

on 2/12/16, 11:36 AM

I already know how that works, very tricky, but works. let me rewrite my answer on that with an example of how to test it

Axel Mendoza
on 3/17/16, 1:11 AM

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Asked: 2/12/16, 8:32 AM
Seen: 2997 times
Last updated: 1/26/17, 2:24 PM