'Validate main FG item'

def validate_main_item(self):

    item = self.get_item_det(self.item)
    if (not item):
        frappe.throw(_(u'Item    {0}    does    not    exist    in    the    system    or    has    expired').format(self.item))
    else:
        ret = frappe.db.get_value(u'Item', self.item, [u'description', u'stock_uom', u'item_name'])
        self.description = ret[0]
        self.uom = ret[1]
        self.item_name = ret[2]
    if (not self.quantity):
        frappe.throw(_(u'Quantity    should    be    greater    than    0'))
