实现功能：抽奖

需求：后台控制每种中奖的概率、控制奖品数量

备注：奖品是以优惠券的形式发放给用户进行兑换，需要考虑到优惠券数量问题

以此为例：

1.获取每个奖品中奖概率，及该奖品的id,我是以1000的总数概率来计算的

/**获取奖品及该奖品的中奖概率 * Created by PhpStorm. * User: Alisa * Date: 2018/12/6 * Time: 18:02 * @param $extract_prize_id * @return mixed */public function user_prize ($extract_prize_id){    $prize = (new Query())        ->from(['p'=>Prize::tableName()])        ->leftJoin(['c'=>Coupon::tableName()],'c.id = p.coupon_id')        ->select('p.prize_pro,p.id')        ->where(['p.extract_prize_id'=>$extract_prize_id])        ->andWhere(['>','c.surplus_num',0])        ->all();    $sum = (new Query())        ->from(['p'=>Prize::tableName()])        ->leftJoin(['c'=>Coupon::tableName()],'c.id = p.coupon_id')        ->where(['p.extract_prize_id'=>$extract_prize_id])        ->andWhere(['>','c.surplus_num',0])        ->sum('p.prize_pro');    $count = count($prize);    foreach ($prize as $k=>$v){        $list[$k] = $v;    }    $list[$count] = [        "prize_pro"=>Math::sub(1000,$sum,0),        "id"=>0    ];    $res = $this->get_rand($list);    return $list[$res]['id'];}

2.进行抽奖计算，返回中奖的奖品id，id是0的话，表示谢谢参与

/**抽奖计算 * Created by PhpStorm. * User: Alisa * Date: 2018/12/6 * Time: 18:10 * @param $proArr * @return int|string */public function get_rand($proArr){    $result = '';    foreach ($proArr as $key => $val) {        $arr[$key] = $val['prize_pro'];    }    // 概率数组的总概率    $proSum = 1000;    // 概率数组循环    foreach ($arr as $k => $v) {        $randNum = mt_rand(1, $proSum);        if ($randNum <= $v) {            $result = $k;            break;        } else {            $proSum -= $v;        }    }    return $result;}

3.进行后续逻辑处理，判断优惠券剩余数量并减去、减去用户抽奖册数、增加用户抽奖记录、中奖的话优惠券到账

/**用户抽奖 * @param $userId * @param $extract_prize_id * @return array|bool * @throws \yii\db\Exception */ public function extractPrize($userId,$extract_prize_id){    $prize_id = $this->user_prize($extract_prize_id);    $coupon_id = 0;    $prize_name = '谢谢参与';    $prize_url = '';    if($prize_id){        $coupon = (new Query())            ->select('c.id,c.name,c.rule,c.validity,c.surplus_num')            ->from(['pr'=>Prize::tableName()])            ->leftJoin(['c'=>Coupon::tableName()],'c.id = pr.coupon_id')            ->where(['pr.id'=>$prize_id])            ->one();        if($coupon['surplus_num'] > 0){            $coupon_id = $coupon['id'];            $prize_name = $coupon['name'];            $url = (new Query())                ->select('pi.url')                ->from(['pr'=>Prize::tableName()])                ->leftJoin(['pi'=>Picture::tableName()],'pi.id = pr.img_id')                ->where(['pr.id'=>$prize_id])                ->one();            $prize_url = $url['url'];        }    }    $trans = Yii::$app->db->beginTransaction();    try{        $model = new ExtractPrizeRecord();        $model->prize_id = $prize_id;        $model->coupon_id = $coupon_id;        $model->prize_name = $prize_name;        $model->user_id = $userId;        $model->type = $extract_prize_id;        $model->create_at = time();        $res_ex = $model->save();        if ( $res_ex ) {            //减去用户抽奖次数            \Yii::$app->db->createCommand("update users set $str = $str - 1 where $str > 0 and user_id = :user_id",                [                    ':user_id' => $userId,                ]            )->execute();            if(($coupon_id > 0) && ($coupon['surplus_num'] > 0)){                //减去优惠券剩余数量                \Yii::$app->db->createCommand("update coupon set surplus_num = surplus_num -1 where id = :coupon_id and surplus_num > 0",                    [                        ':coupon_id' => $coupon_id,                    ]                )->execute();                $myModel = new MyCoupon();                $myModel->user_id = $userId;                $myModel->name = $coupon['name'];                $myModel->rule = $coupon['rule'];                $myModel->coupon_id = $coupon_id;                $myModel->create_at = time();                $myModel->update_at = time();                $myModel->start_at = time();                $myModel->end_at = time() + $coupon['validity']* 86400;                $myModel->re_code = StringTools::randString(10);                $myModel->coupon_number = date('YmdHis') . rand(10000000,99999999);                $myModel->save();            }        } else {            return false;        }        $trans ->commit();        return ['prize_name'=>$prize_name,'prize_url'=>$prize_url];    }catch (\Throwable $t) {        $trans->rollBack();        return false;    }}

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