how to remove the default value for the fields.integer ?

You may use the "_defaults" dictionary to give the default value for any field.
Each "_defaults" needs either a method name (the method will be called to get the default value, or a one-liner lambda function that just returns the default value. On OpenERP 6.0 you can also just use the value.

class my_example(osv.osv):
     _name = 'my.example'
     _columns = {
         'my_integer': fields.integer('My Integer'),
     }
     _defaults = {
         'my_integer': lambda *a: -1, # Set -1 as the default value for the field "my_integer".
         #'my_integer': -1, # This works on OpenERP 6.0, but not 5.0
     }

And the optional parameters for fields.integer() are these (taken from the technical memento here: http://doc.openerp.com/memento/OpenERP_Technical_Memento_v0.6.4.pdf):

• string: field label (required).
• required: True if mandatory.
• readonly: True if not editable.
• help: help tooltip.
• select: 1 to include in search views and optimize for list filtering (with database index).
• context: dictionary with contextual parameters (for relational fields).
• change_default: True if field should be usable as condition for default values in clients.
• states: dynamic changes to this field's common attributes based on the state field.

Bushair, as far as I know integers can't be set to "None" in OpenERP.
I think it could be useful in some situations, feel free to post a wishlist bug report against openobject-server.
Lionel.

On Monday 25 October 2010, you wrote:
> Question #129587 on OpenObject Server changed:
> https://answers.launchpad.net/openobject-server/+question/129587
>
> Numérigraphe proposed the following answer:
> Bushair, as far as I know integers can't be set to "None" in OpenERP.
> I think it could be useful in some situations, feel free to post a wishlist
> bug report against openobject-server. Lionel.

FYI, we have been running a branch with None-support for integers, in
anticipation of any bugs that may appear from such a feature. So far, only
some minor issues have only come up (and fixed).
If this branch is proven, we could consider merging this feature in a *later*
version of OpenERP (not in current 6.0 series, AFAICT).

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