xxxxx.xxxxx.campaign.platform.update
        ===================================
        取得一个推广计划的投放平台设置

def update(self, campaign_id, search_channels, nonsearch_channels, outside_discount, nick=None):
        '''xxxxx.xxxxx.campaign.platform.update
        ===================================
        取得一个推广计划的投放平台设置'''
        request = TOPRequest('xxxxx.xxxxx.campaign.platform.update')
        request['campaign_id'] = campaign_id
        request['search_channels'] = search_channels
        request['nonsearch_channels'] = nonsearch_channels
        request['outside_discount'] = outside_discount
        if nick!=None: request['nick'] = nick
        self.create(self.execute(request), fields=['success','result','success','result_code','result_message'], models={'result':CampaignPlatform})
        return self.result