Here is my .py file

class Associateaccounts_respartner(models.Model):
 _inherit = 'res.partner'    
@api.multi   
 def associate_count():       
 # I need to count how many associate account is there based on one particular contact

  associate_count = fields.Integer(compute="associate_count", string='# of Associate', store='true')
 associate_id = fields.One2many('sale.associateaccounts', 'associate_partner_id', string='Associate Accounts')
here is my .xml file
<openerp>    
<data>        
<record id="count_associateaccounts_respartner" model="ir.ui.view">            
<field name="inherit_id" ref="base.view_partner_form"/>           
 <field name="model">res.partner</field>           
 <field name="arch" type="xml">                 
<div name="button_box" position="inside">                   
 <button class="oe_stat_button" type="action" name="%(associateaccounts.associateaccounts_action)d"                        attrs="{'invisible': [('customer', '=', False)]}"                        icon="fa-star">                        
<field string="Associates" name="associate_count" widget="statinfo"/> 
 </button>                
</div>             
</field>        
</record>    
</data>
</openerp>