I develop new module 

and i have  Char field`cont_no` how make it searchable in database if entred exsist (like many2one autocomplate)

Model.py

`

class RealContract(models.Model):
    _name = 'real.contracts'
    _sql_constraints = [
        ('contract_no_unique', 'unique (cont_no)', 'You Enter Number Already exsist! \n Contract Number Must be Unique!')]
    cont_no = fields.Char('Contract No.', index=True, search='_search_function',
                          filter_domain="[('cont_no','ilike',self)]", required=True)
    real_id = fields.Many2one('real.realstate', 'Real State.', ondelete='restrict')

`

view.xml

`

<record model="ir.ui.view" id="real.contract_form">
  <field name="name">Contracts Form</field>
  <field name="model">real.contracts</field>
  <field name="arch" type="xml">
    <form>
      <sheet>
        <group>
            <field name="cont_no" filter_domain="[('cont_no','ilike',self)]"/>
          </group>
      </sheet>
    </form>
  </field>
</record>

`

how do it?

Thanks