Hi guyz, I'm getting this error: RuntimeError: maximum recursion depth exceeded. But the code was working fine before sometime.

When I searched regarding this issue, many results pointed to execution time taken due to python and also explanations were difficult to understand.

Can anyone give me suggestion regarding this error.

In sample.py:

from osv import fields, osv
import time

class sample(osv.osv):
    def onchange_state(self, cr, uid, ids, state_id, context=None):
        if state_id:
            country_id = self.pool.get('res.country.state').browse(cr, uid, state_id, context).country_id.id
            return {'value':{'country_id':country_id}}
        return {}   
    def _calculate(self, cr, uid, ids, fields, arg, context):
        x={}
        for record in self.browse(cr, uid, ids):
            x[record.id]= record.field_a + record.field_b
        return x
    _name = "sample"
    _table = "sample"
    _rec_name = "name"
    _log_access = True
    _description = "Simple Form"
    _columns = {
             'name':fields.char('Name', size=32, required=True),
             "age" : fields.integer("age"),
             "length": fields.integer("length"),    
             'address': fields.text('Address'),
             'flag': fields.boolean('Flag'),
             'date': fields.date('Date'),
             'datetime': fields.datetime('Date with Time'),
             'confirm': fields.selection((('unconfirmed', 'Unconfirmed'), ('confirmed', 'Confirmed')),
                  'Selection Box'),
             'image': fields.binary("Image"),
             "phone" : fields.char("phone"),

             'user_id': fields.many2one('res.users', 'Salesperson'),
             'partner_id': fields.many2one('res.partner', 'Customer', ondelete='cascade'),
             'location_id' : fields.related('location_id', type="many2one", relation="stock.location", string="Location Id"),
             'state_id': fields.many2one("res.country.state", 'State'),
             'country_id': fields.many2one('res.country', 'Country'),
             'country': fields.related('country_id', type='many2one', relation='res.country', string='Country'), 

             'duration' : fields.float('Duration'),

             'field_a' : fields.integer('Number1') ,
             'field_b' : fields.integer('Number2'),
             'result'  : fields.function(_calculate, type='integer', obj='sample', method=True, store=False, string='Result'),
    }

    _defaults = {  
        'date': fields.date.context_today,
        }

sample()

In sample_view.xml:

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
    <data>

        <record model="ir.ui.view" id="test_tree_view">
            <field name="name">test.tree</field>
            <field name="model">sample</field>
            <field name="type">tree</field>
            <field name="arch" type="xml">
                <tree string="test" toolbar="1">
                    <field name="name" />
                    <field name="age" />
                    <field name="date" />
                </tree>
            </field>
        </record>

        <record model="ir.ui.view" id="test_form_view">
            <field name="name">test.form</field>
            <field name="model">sample</field>
            <field name="arch" type="xml">
                <form string="test" version="7.0">

                    <header>
                        <button name="header_button" string="Create" type="object" />
                        <field name="confirm" widget="statusbar" statusbar_visible="unconfirmed,coked"
                            statusbar_colors='{"unconfirmed":"red","confirmed":"blue"}'
                            clickable="True" />
                        <!-- <field name="name" widget="statusbar" statusbar_visible="draft,sent,invoiced,done" 
                            statusbar_colors='{"draft":"red","done":"blue"}' /> -->
                    </header>

                    <sheet>
                        <group>
                            <label string="Label" colspan="2" />
                            <field name="name" select="1" />
                            <field name="state_id" string="State" onchange="onchange_state" />
                            <field name="country_id" string="Country" />
                            <field name="country" />
                            <field name="location_id" /> 
                            <separator string="seperator tag inserted here"
                                colspan="4" />
                            <newline />
                            <notebook colspan="4" tabpos="up">
                                <page string="basic data field">
                                    <group>
                                        <field name="age" select="2" />
                                        <field name="length" select="3" />
                                        <field name="address" placeholder="Provide current address..." />
                                        <field name="flag" />
                                        <field name="date" />
                                        <field name="datetime" />
                                        <field name="confirm" />
                                        <field name="image" />
                                        <field name="state_id" />
                                        <field name="country_id" />
                                    </group>
                                </page>
                                <page string="relational data field">
                                    <group>
                                        <field name="user_id" string="user_id(many2one)" />
                                        <!-- <field name="partner_ids" string="partner_ids(one2many)" /> -->
                                    </group>
                                </page>
                                <page string="functional data field">
                                    <group>
                                        <field name="field_a" />
                                        <field name="field_b" />
                                        <field name="result" />
                                    </group>
                                </page>
                                <page string="calendar">
                                    <group>
                                        <field name="user_id" string="conducted by" />
                                        <field name="datetime" string="scheduled date" />
                                        <field name="duration" />
                                        <field name="partner_id" string="member to attend" />
                                    </group>
                                </page>
                            </notebook>
                        </group>

                        <!-- <button name="Submit" string="Button" icon="STOCK_APPLY" special="save" 
                            colspan="2" type="action" target="new" confirm="Ask for Confirmation" /> -->

                    </sheet>
                </form>
            </field>
        </record>

        <record model="ir.ui.view" id="sample_kanban_view">
            <field name="name">Kanban</field>
            <field name="model">sample</field>
            <field name="arch" type="xml">
                <kanban>
                    <field name="name" />
                    <!-- <field name="code" /> <field name="lst_price" /> -->
                    <templates>
                        <t t-name="kanban-box">
                            <div class="oe_kanban_vignette oe_semantic_html_override">
                                <a type="open">
                                    <img t-att-src="kanban_image('sample', 'image', record.id.value)"
                                        class="oe_kanban_image" />
                                </a>
                                <div class="oe_kanban_details">
                                    <h4>
                                        <a type="open">
                                            <!-- <t t-if="record.code.raw_value"> [ <field name="code" /> 
                                                ] </t> -->
                                            <field name="name" />
                                        </a>
                                    </h4>
                                    <div name="tags" />
                                    <ul>
                                        <li>
                                            Age:
                                            <field name="age"></field>
                                        </li>
                                    </ul>
                                </div>
                            </div>
                        </t>
                    </templates>
                </kanban>
            </field>
        </record>

        <record model="ir.ui.view" id="sample_graph">
            <field name="name">sample.graph</field>
            <field name="model">sample</field>
            <field name="type">graph</field>
            <field name="arch" type="xml">
                <graph string="Graph string" orientation="horizontal" type="bar">
                    <field name="name" group="True" />
                    <field name="age" operator="*" />
                </graph>
            </field>
        </record>

        <record model="ir.ui.view" id="sample_calendar_view">
            <field name="name">sample.calendar</field>
            <field name="model">sample</field>
            <field name="type">calendar</field>
            <field name="arch" type="xml">
                <calendar string="Reminders" date_start="datetime" color="user_id"
                    date_delay="duration" mode="week">
                    <field name="name" modifiers="{'required': true}" />
                    <field name="partner_id" modifiers="{}" />
                </calendar>
            </field>
        </record>

        <record model="ir.ui.view" id="sample_search_view">
            <field name="name">sample.search</field>
            <field name="model">sample</field>
            <field name="type">search</field>
            <field name="arch" type="xml">
                <search>
                    <group expand="1" string="Group By...">
                        <filter string="Users" icon="terp-project" domain="[]"
                            context="{'group_by':'user_id'}" />
                        <filter string="Partner" icon="terp-project" domain="[]"
                            context="{'group_by':'partner_id'}"  />
                        <separator orientation="vertical" />
                        <filter string="Date" icon="terp-project" domain="[]"
                            context="{'group_by':'date'}" />
                        <filter string="Current State" domain="[('confirm','in',('unconfirmed','confirmed'))]" help="Confirmed and Unconfirmed Tasks" icon="terp-project"/>
                        <field name="location_id" string="Location"
                            filter_domain="['|',('location_id','ilike',self),('location_dest_id','ilike',self)]" />
                    </group>
                </search>
            </field>
        </record>

        <record model="ir.ui.view" id="sample_gantt_view">
            <field name="name">sample.gantt</field>
            <field name="model">sample</field>
            <field name="type">gantt</field>
            <field name="arch" type="xml">
                <gantt color="user_id" date_delay="duration" date_start="datetime"
                    string="Tasks" mode="3months">
                    <level object="crm.make.sale" link="partnet_id" domain="[]">
                        <field name="name" />
                    </level>
                </gantt>
            </field>
        </record>

        <record model="ir.actions.act_window" id="action_test_form">
            <field name="name">sample</field>
            <field name="res_model">sample</field>
            <field name="view_type">form</field>
            <field name="view_mode">kanban,tree,form,graph,calendar,gantt</field>
        </record>

        <menuitem name="testParent" icon="terp-project" id="testParent_menu"
            sequence="0" />

        <menuitem name="NotesChild" parent="testParent_menu" id="NotesChild_menu" />

        <menuitem name="Header" parent="NotesChild_menu" id="Header_menu_mainform"
            action="action_test_form" />
    </data>

</openerp>

__openerp__.py:

#coomentnds
{
    "name" : "sample",
    "version" : "0.1",
    "author" : "Atchuthan",
    "category" : "Generic Modules/Others",
    "depends" : ["base", "stock"],
    "description" : "Simple demo form",
    "demo_xml" : [],
    "data" : ["sample_view.xml"],
    "active": False,
    "installable": True
}