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golang. 批量获取redis中的缓存值 原

 5 years ago
source link: https://studygolang.com/articles/14605?amp%3Butm_medium=referral
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使用redis的pipeline，批量获取redis中的key值时，报错，分析发现，批量获取时，exec后，会返回两种值：nil 及 redis.Nil，

这种情况下，使用常规的 if err!=nil 的判断方法判断错误，是会报错的。

测试代码：

package main

import (
	"github.com/go-redis/redis"
	"log"
	"strconv"
)

func main() {
	client := redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Password: "", // no password set
		DB:       0,  // use default DB
		Network:  "tcp",
		PoolSize: 50,
	})

	if _, err := client.Ping().Result(); err != nil {
		panic(err)
	}

	pipe := client.Pipeline()

	log.Println("所有的key都存在:")
	for i := 0; i < 4; i++ {
		key := "n:" + strconv.FormatInt(int64(i), 10)
		pipe.Get(key)
	}

	result, err := pipe.Exec()

	log.Println(result)
	log.Println(err == nil)
	log.Println(err == redis.Nil)

	log.Println("有不存在的key:")
	for i := 0; i < 5; i++ {
		key := "n:" + strconv.FormatInt(int64(i), 10)
		pipe.Get(key)
	}

	result, err = pipe.Exec()

	log.Println(result)
	log.Println(err == nil)
	log.Println(err == redis.Nil)

	defer client.Close()

}

运行结果：

Qj2aMvA.jpg!web

可以看到，如果批量获取的key中，有不存在的key，返回的会是redis.Nil，否则返回的是nil。


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