值未显示在OpenERP的选择字段中;从postgres数据库中检索值

Question

Python文件：

#!/usr/bin/python
from openerp.osv import fields, osv
import psycopg2
import sys
import pprint


select_list=[('SL01','CONSTRUCTION/BUILDING'),('SL02','CAPITAL/CAPEX'),('SL03','ELECTRICAL')]

select_sub1_list=[('ECDS08','CAPACITIOR'),('EDS07','RESISTANCE'),('EDS06','TRANSISTORS'),('EDS05','THYRISOSTRS'),('EDS04','SENSORS'),('EDS03','SINKS AND ELEMENTS'),('EDS02','DIODES'),('ECDS01','ELECTRONICS')]

select_sub2_list=[('01','Blue Capacitor'),('02','Blue Capacitor Mov')]

#select_sub3_list=[('01','470PF/1KV'),('02','CE471/1KV'),('03','B101K/1KV'),('04','CE474/100V')]

class laser_products(osv.osv):
    _inherit = "product.product"

    def select_return(self, cr, uid, ids=None, context=None):
        conn_string = "host='localhost' dbname='new_scantech_laser' user='postgres' password='12345'"
        conn = psycopg2.connect(conn_string)
        cursor = conn.cursor()
        cursor.execute("""SELECT main_cat from product_product""")
        records = cursor.fetchall()
        s=conn.commit()         
        return (records)

    _columns = {
        'laser_product_select': fields.selection(select_list,'Main category'),
        'laser_sub1_product_select': fields.selection(select_sub1_list,'Sub 1 category'),
    'laser_sub2_product_select': fields.selection(select_sub2_list,'Sub 2 category'),
    'laser_sub3_product_select': fields.many2one("laser.erp",'Sub 3 category'),
        'main_cat' : fields.selection(select_return,'Main sub Category'),
        'temp1':fields.char("Product Code", readonly=True),

    }


    def onchange_laser_product_select(self,cr,uid,ids,laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context=None):
        if(laser_product_select or laser_sub1_product_select or laser_sub2_product_select or laser_sub3_product_select):
        if not (laser_sub1_product_select and laser_sub2_product_select and laser_sub3_product_select):
                vals123 = {'default_code': str(laser_product_select)}        
                return {'value': vals123}
        else:
            if not (laser_sub2_product_select and laser_sub3_product_select):
                    vals123 = {'default_code': str(laser_product_select) + str(laser_sub1_product_select)}
            return {'value':vals123}
            else:
                    if not (laser_sub3_product_select):
                        vals123 = {'default_code': str(laser_product_select) + str(laser_sub1_product_select)+str(laser_sub2_product_select)}
                return {'value':vals123}
            else:
                vals123 = {'default_code': str(laser_product_select) + str(laser_sub1_product_select)+str(laser_sub2_product_select) + str(laser_sub3_product_select)}
                return {'value':vals123}    


laser_products()

class laser_erp(osv.osv):
    _name = "laser.erp"
    _columns = {
                'name': fields.char('Sequence') 
    }

XML文件：

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data noupdate="1">
    <record model="ir.ui.view" id="laser_product_project">
        <field name="name">product.normal.form</field>
        <field name="model">product.product</field>
        <field name="inherit_id" ref="product.product_normal_form_view"/>
        <field name="arch" type="xml"> 
            <field name='list_price' position="after">
                    <field name="laser_product_select" on_change="onchange_laser_product_select(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)" on_change1="onchange_laser_product_select1(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)" />
                    <field name="laser_sub1_product_select" on_change="onchange_laser_product_select(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)" on_change1="onchange_laser_product_select1(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)"/>

                    <field name="laser_sub2_product_select" on_change="onchange_laser_product_select(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)" on_change1="onchange_laser_product_select1(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)"/>
            <field name="laser_sub3_product_select" on_change="onchange_laser_product_select(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)" on_change1="onchange_laser_product_select1(laser_product_select,laser_sub1_product_select,laser_sub2_product_select,laser_sub3_product_select,context)"/>

                       <field name="main_cat"/>               
                  </field>              


       </field>
    </record>       

  </data>
</openerp>

在此主要子类别字段中是选择字段。它显示空白选择列表。实际上数据库中有4个条目，它显示了四个选择列表，但它们是空白请帮帮我