英文:
Redigo multi requests
问题
我之前一直使用以下代码来确保返回的数据是一个字节切片:
data, err := redis.Bytes(c.Do("GET", key))
然而,现在我需要在Redis请求中添加一个额外的命令,所以代码变成了这样:
c.Send("MULTI")
c.Send("GET", key)
c.Send("EXPIRE", key)
r, err := c.Do("EXEC")
但是现在我似乎无法让GET
命令返回一个字节切片。我尝试了在下面的代码中添加redis.Bytes
,但没有成功:
c.Send("MULTI")
redis.Bytes(c.Send("GET", key))
c.Send("EXPIRE", key)
r, err := c.Do("EXEC")
请帮我看看如何解决这个问题。谢谢!
英文:
I have previously been using this:
data, err := redis.Bytes(c.Do("GET", key))
to make sure that data returned is a slice of bytes.
However, I now need to add an extra command to the Redis request so I have something like this:
c.Send("MULTI")
c.Send("GET", key)
c.Send("EXPIRE", key)
r, err := c.Do("EXEC")
but now I can't seem to make the GET
command return a slice of bytes. I've tried adding redis.Bytes
like below but no luck.
c.Send("MULTI")
redis.Bytes(c.Send("GET", key))
c.Send("EXPIRE", key)
r, err := c.Do("EXEC")
答案1
得分: 6
在Redis中,EXEC
命令返回一个包含事务中所有命令结果的数组。
redigo提供了一个Values
函数,用于将数组命令的回复转换为[]interface{}
。
c.Send("MULTI")
c.Send("GET", key)
c.Send("EXPIRE", key)
r, err := redis.Values(c.Do("EXEC"))
现在,r[0]
中包含了你的GET
命令的回复作为一个interface{}
,所以你需要进行类型断言来获取你期望的字节切片:
data := r[0].([]byte)
参考资料
Values
函数:https://godoc.org/github.com/garyburd/redigo/redis#Values- 类型断言:https://golang.org/ref/spec#Type_assertions
英文:
In redis, the EXEC
command returns an array containing the results of all the commands in the transaction.
redigo provides a Values
function, which converts an array command reply to a []interface{}
.
c.Send("MULTI")
c.Send("GET", key)
c.Send("EXPIRE", key)
r, err := redis.Values(c.Do("EXEC"))
r[0]
now has the reply from your GET
command as a interface{}
, so you'll need to do a type assertion to get the slice of bytes you're expecting:
data := r[0].([]byte)
References
- func Values: https://godoc.org/github.com/garyburd/redigo/redis#Values
- Type assertions: https://golang.org/ref/spec#Type_assertions
答案2
得分: 4
MULTI
用于以原子方式向Redis发送多个命令,创建一个事务。这与管道完全不同。
在调用EXEC
之前,所有的命令都不会被实际执行,因此在事务内部调用GET
时无法获取值。
根据文档:
> 当Redis连接处于MULTI请求的上下文中时,所有命令都将回复字符串"QUEUED"(从Redis协议的角度来看,作为状态回复发送)。排队的命令只是在调用EXEC时被安排执行。
在redigo中,管道传输是以不同的方式进行的:
http://godoc.org/github.com/garyburd/redigo/redis#hdr-Pipelining
你想要做的是像这样(未经测试):
c.Send("GET", key)
c.Send("EXPIRE", key)
c.Flush()
v := redis.Bytes(c.Receive()) // GET的回复
_, err = c.Receive() // EXPIRE的回复
英文:
MULTI
is used to send several commands in an atomic way to Redis, by creating a transaction. This is not a pipeline at all.
None of the commands will be actually executed before the EXEC
call so it is impossible to obtain the value when you call GET
from within a transaction.
From the docs:
> When a Redis connection is in the context of a MULTI request, all commands will reply with the string QUEUED (sent as a Status Reply from the point of view of the Redis protocol). A queued command is simply scheduled for execution when EXEC is called.
In redigo pipelining is done in a different way:
http://godoc.org/github.com/garyburd/redigo/redis#hdr-Pipelining
What you want to do is something like this (untested):
c.Send("GET", key)
c.Send("EXPIRE", key)
c.Flush()
v := redis.Bytes(c.Receive()) // reply from GET
_, err = c.Receive() // reply from EXPIRE
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