from osv import fields,osv
class name_model(osv.osv):
    _name='name.model'
    _columns={
              'name':fields.char('Name',size=32)}
name_model()

class first_model(osv.osv):
    _name='first.model'
    _columns={
              'name1':fields.many2one('name.model','Name1'),
              'name2':fields.many2one('name.model','Name2'),
              'cost':fields.integer('Cost')}
first_model()

class second_model(osv.osv):
    _name='second.model'
    _columns={
              'name1':fields.many2one('name.model','Name1'),
              'name2':fields.many2one('name.model','Name2'),
              'select_cost':fields.integer('Select Cost')}
    def onchange_cost(self,cr,uid,ids,name2,context=None):
        value={}
        #print "Name 1",name1
        print "Name 2",name2
        return {'value':value}

second_model()

and xml_code

<openerp>
    <data>

    <!-- Test model View -->
    <menuitem id="menu_institution_main" name="Institution Management"
             sequence="3"/>
    <menuitem id="sample_cost" name="Sample" parent= "menu_institution_main" sequence="1"/>

    <!-- Name : Fee Type : Tree View -->

        <record id="view_cost_tree" model="ir.ui.view">
            <field name="name">first.model</field>
            <field name="model">first.model</field>
            <field name="type">tree</field>
            <field name="arch" type="xml">
                <tree string="First model">
                    <field name="name1"/>
                    <field name="name2"/>
                    <field name="cost"/>
                </tree>
            </field>        
        </record>




        <!-- Name : Fee Type : Form View -->

        <record id="view_cost_form" model="ir.ui.view">
            <field name="name">first.model</field>
            <field name="model">first.model</field>

            <field name="arch" type="xml">
                <form string="First Model" version="7.0">
                    <group>             
                        <field name="name1"/>
                        <field name="name2"/>
                        <field name="cost"/>
                    </group>    
                </form>
            </field>        
        </record>

        <!--Name : Fee Type Action : Action Menu  -->

        <record id="action_cost" model="ir.actions.act_window">
            <field name="name">First Model</field>
            <field name="type">ir.actions.act_window</field>
            <field name="res_model">first.model</field>
            <field name="view_type">form</field>
            <field name="view_mode">tree,form</field>
            <field name="view_id" ref="view_cost_tree"/>
        </record>


       <menuitem name="Sample Cost" action="action_cost" id="menu_action_cost" parent="sample_cost" sequence="0"/>
    </data>
</openerp>