First of all you have to define a new Object. You can do that by adding your custom module.

Eg for new object:- file is " custom_test.py"

from osv import osv,fields
from openerp.tools.translate import _

class custom_class(osv.osv):
    _name='custom.class'
    _columns={
              'names' : fields.char('Name', size=128, required=True),
              'class' : fields.char(string='Class', required=True),
              'code' : fields.char(string='Code'),
              }
    
custom_class()

class custom_subject(osv.Model):
    _name = "custom.subject"
    _description = "Subjects"
    _columns = {
        'name': fields.char('Name', size=64, required=True),
        'code': fields.char('Code', size=12, required=True),
        'maximum_marks': fields.integer("Maximum marks", size=5),
        'minimum_marks': fields.integer("Minimum marks", size=5),
        'weightage': fields.integer("Weightage", size=10),
        'is_practical':fields.boolean('Is Practical', help='Check this if subject is practical.'),
        'no_exam' : fields.boolean("No Exam", help='Check this if subject has no exam.'),

    }
custom_subject()

Then you have to define your view  file

Steps to add menu item:-

1. define your menu item

      Eg:

        <menuitem   icon="terp-project" id="my_test_menu"   name="My Test" sequence="4" action="action_my_form"/>

**This is your main menu item that shows in your tab

2. define your action

Eg:

        <record model="ir.actions.act_window" id="action_my_form">
            <field name="name">Class</field>
            <field name="res_model">custom.class</field>
            <field name="view_type">form</field>
            <field name="view_id" ref="my_test_form" />
            <field name="view_mode">tree,form</field>
        </record>

**here i defined action for my main menu item and specified its view types

3. then you can link your views to action

Eg:

        <record id="action_my_form_tree" model="ir.actions.act_window.view">
            <field name="view_mode">tree</field>
            <field name="view_id" ref="my_test_tree"/>
            <field name="act_window_id" ref="action_my_form"/>
        </record>

**here i linked my tree view to action, you can link your each view like this,ie form,search etc....

My custom view file "custom_test_view.xml" as follows:

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

    
         <record model="ir.ui.view" id="my_test_form">
            <field name="name">my.test.form</field>
            <field name="model">custom.class</field>
            <field name="arch" type="xml">
            <form string="Class Information" version="7.0">
                   <sheet>
                        <group col="4" colspan="4">
                            <field name="names" />
                            <field name="class" />
                            <field name="code" />
                        </group>
                    </sheet>
            </form>
         </field>
      </record>
    
    
        <record model="ir.ui.view" id="my_test_tree">
            <field name="name">my.test.tree</field>
            <field name="model">custom.class</field>
            <field name="arch" type="xml">
                <tree string="Class">
                    <field name="class"/>
                    <field name="code"/>
                </tree>
            </field>
        </record>
                            
       
       
       
        <record model="ir.ui.view" id="view_custom_subject_form">
            <field name="name">custom.subject.form</field>
            <field name="model">custom.subject</field>
            <field name="arch" type="xml">
                <form string="Subjects" version="7.0">
                    <sheet>
                        <group col="4" colspan="4">
                            <field name="name" placeholder="Name"/>
                            <field name="code" placeholder="Code"/>
                            <field name="maximum_marks" />
                            <field name="minimum_marks" />
                            <field name="weightage" />
                            <field name="is_practical"/>
                            <field name="no_exam"/>
                        </group>

                    </sheet>
                </form>
            </field>
        </record>
       
        <record model="ir.ui.view" id="view_custom_subject_tree">
            <field name="name">custom.subject.tree</field>
            <field name="model">custom.subject</field>
            <field name="arch" type="xml">
                <tree string="Subjects">
                    <field name="name"/>
                    <field name="code"/>
                    <field name="maximum_marks"/>
                    <field name="minimum_marks"/>
                    <field name="weightage"/>
                    <field name="no_exam"/>
                </tree>
            </field>
        </record>
       
       
       
               
        <record model="ir.actions.act_window" id="action_my_form">
            <field name="name">Class</field>
            <field name="res_model">custom.class</field>
            <field name="view_type">form</field>
            <field name="view_id" ref="my_test_form" />
            <field name="view_mode">tree,form</field>
        </record>
       
        <record id="action_my_form_tree" model="ir.actions.act_window.view">
            <field name="view_mode">tree</field>
            <field name="view_id" ref="my_test_tree"/>
            <field name="act_window_id" ref="action_my_form"/>
        </record>
       
        <record model="ir.actions.act_window" id="action_subjects_form">
            <field name="name">Subjects</field>
            <field name="res_model">custom.subject</field>
            <field name="view_type">form</field>
            <field name="view_id" ref="view_custom_subject_form"/>
            <field name="view_mode">tree,form</field>
        </record>
       
        <record id="action_view_custom_subjects_tree" model="ir.actions.act_window.view">
            <field name="view_mode">tree</field>
            <field name="view_id" ref="view_custom_subject_tree"/>
            <field name="act_window_id" ref="action_subjects_form"/>
        </record>
       
       
        <record id="action_view_custom_subjects_form" model="ir.actions.act_window.view">
            <field name="view_mode">form</field>
            <field name="view_id" ref="view_custom_subject_form"/>
            <field name="act_window_id" ref="action_subjects_form"/>
        </record>
       
       
             
    
        <menuitem
            icon="terp-project" id="my_test_menu"
            name="My Test" sequence="4"
            action="action_my_form"/>
                                                
        <menuitem
            name="Subjects" parent="my_test_menu"
            id="menu_subjects"
            sequence="2"/>
        
        <menuitem name="Subjects Details" parent="menu_subjects"
            id="menu_sub_subject" action="action_subjects_form"/>
                        
    </data>
</openerp>

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