Hi, im trying to implement a simple search function in open erp 7. It will search and list all records based on management code, but the problem is management code is a type many2one and its a field in another model. when i run it, it gives me an error like this below.What do i need to change to make it work?

ProgrammingError: operator does not exist: integer ~~* unknown LINE 1: ...t_org_table" WHERE ("budget_org_table"."management_code" ilike '%12... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts

my xml code

  <record id="feature_search" model="ir.ui.view">
        <field name="name">management.feature_inventory.search</field>
        <field name="model">management.feature_inventory</field>
        <field name="arch" type="xml">
            <search string="Feature Inventory">
        <field name="management_code" string="Management Unit Code"/>
                <field name="year" string="Year"/>
            </search>
        </field>
    </record>

my model

class feature_inventory(osv.osv):

_name = "management.feature_inventory"
_description = "Feature Inventory"
_rec_name = "feature_code"
_columns = {
    'feature_code' : fields.many2one("budget.feature_details","Code", required=True),
    'management_unit_code' : fields.many2one("budget.org_table", "Management Unit Code", required=True),
    'Total' : fields.integer("Total"),
    'condition_1' : fields.integer("Condition 1"),
    'condition_2' : fields.integer("Condition 2"),
    'condition_3' : fields.integer("Condition 3"),
    'year' : fields.integer("Year", size=64, required=True),
}
_sql_constraints = [
    ('feature_code_unique', 'UNIQUE(feature_code)', 'Each feature_code is unique.'),
]

please help...