Views in OpenErp:- Two type of views in openerp
1- From Views
2- Tree Views

1- From Views:- In OpenErp Form Views follow many point like as
By default, each field is preceded by a label, with its name.
Fields are placed in screen right to left and top to bottom.
A view field can use several columns.

Example:-
    <record id="view_invoice_penalty_form" model="ir.ui.view">
            <field name="name">penalty.form</field>
            <field name="model">add.penalty</field>
            <field name="type">form</field>
            <field name="arch" type="xml">
                <form string="Penalty" >
                <field name="date"/>
                <field name="test"/>
                </form>
            </field>
    </record>

2- Tree Views:- In OpenErp Tree Views are used when we work in list mode on the screen .

Example:-

<record id="view_invoice_penalty_form" model="ir.ui.view">
        <field name="name">penalty.form</field>
        <field name="model">add.penalty</field>
        <field name="type">form</field>
        <field name="arch" type="xml">
        <form string="Penalty" > 

              <<field name="date"/>
            <field name="test"/>
         </form>
       </field>
  </record>

onChange method:- In OpenErp On change methods can be executed during the creation of a row, long before it is effectively saved into the database.

Onchange method look like as:



   * .xml:- in xml file
           <field name="name" on_change="name_change(name, address, city)"/>

        * .py:- in py file</br>
           def name_change(self, cr, uid, ids, name, address, city, context=None):
            ...
            return {
                'value': {
                    'address': ...
                    'city': ...
                }
            }