Below code is asset inherited class . Here i will add **'place'** field with **'Karn/Bang/Kengeri'** and **'karn/bang/malleshwaram'** for 'Karn/Bang/Kengeri' will add 'asset_catg_id' with A and B. then for 'karn/bang/malleshwaram' with Y and Z.

Now at calander inherited class . if i select **'place'** with **'Karn/Bang/Kengeri'** then next field **'asset_catg_id'** i have to get only **A and B** drop down list. if again **'karn/bang/malleshwaram'** then i have to get only **Y,Z** options . and previous selected **'asset_catg_id'** values should get deleted . i have tried with domain filter option got **keyvalue error**

    class asset_asset(osv.osv):
    	_inherit = "asset.asset"
    	#_name = "asset_asset"
    	_rec_name= "folio_num"
    	_columns = {
    		'name': fields.char('Asset Name', size=64),
    		'place': fields.many2one('asset.parentlocation', 'Location'),
    		'asset_catg_id' : fields.many2one('asset.catg', 'Asset Catg Selection', select=True, required=True),}
    class asset_catg(osv.Model): 
    	_name="asset.catg" 
    	_rec_name='name1'
    	_description="Define Asset Catgs" 
    	_columns={ 'name1':fields.char('Asset Catg Names',size=64,required=True),}
    asset_catg()
    class asset_parentlocation(osv.osv):
    	_name="asset.parentlocation"
    	_rec_name="location_name"
    	_columns = {
    		'location_name' : fields.char('Asset Location', required=True),
    		'parent_location' : fields.many2one('asset.parentlocation','Parent Location'),
    		'nameee':fields.many2one('ir.attachment','Attachments'),}
    	def name_get(self, cr, uid, ids, context=None):
    		if context is None:
    		    context = {}
    		if not ids:
    		    return []
    		reads = self.read(cr, uid, ids, ['location_name','parent_location'], context=context)
    		res = []
    		for record in reads:
    		    name = record['location_name']
    		    if record['parent_location']:
    		        name = record['parent_location'][1]+' / '+name
    		    res.append((record['id'], name))
    		return res
    **Following code is calendar inherited class** 
    class calendar_event(osv.osv):
    	_inherit = "calendar.event"
    	_rec_name = 'number'
    	_columns = {
    			'number' : fields.char('Meeting ID',readonly=1),
    			#'place' : fields.many2one('stock.location','Substation Location',),
    			'place' : fields.many2one('asset.parentlocation','Substation Location',),
    			#'location' : fields.selection(STATUS_SELECTION,'Location',  default='Board A'),
    			'asset_catg_id' : fields.many2one('asset.catg','Asset Catg Selection', domain="[('asset_catg_id', '=',place)]"),}