Question

请考虑以下示例：

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <hiredis/hiredis.h>

int main(int argc, char **argv) {
  redisContext *redis;
  redisReply *reply;

  redis = redisConnect("127.0.0.1", 6379);
  if(redis->err) {
    fprintf(stderr, "Connection error: %s\n", redis->errstr);
    exit(EXIT_FAILURE);
  }

  reply = redisCommand(redis, "SET %s %s", "foo", "bar");
  printf("SET %s %s: %s\n", "foo", "bar", reply->str);
  freeReplyObject(reply);

  reply = redisCommand(redis, "SET %s %s", "name", "value");
  printf("SET %s %s: %s\n", "name", "value", reply->str);
  freeReplyObject(reply);

  reply = redisCommand(redis, "MGET %s %s", "foo", "name");
  printf("MGET %s %s: %s\n", "foo", "name", reply->str);
  freeReplyObject(reply);

  exit(EXIT_SUCCESS);
}

输出结果为：

PING: PONG
SET foo bar: OK
GET foo: bar
SET name value: OK
MGET foo name: (null)

这是关于MGET的回归。我可以使用hiredis获得多键吗？

Lorem ipsum dolor坐下来。 Lorem ipsum dolor坐着。 Lorem ipsum dolor坐着。 Lorem ipsum dolor坐着。 Lorem ipsum dolor坐着。 Lorem ipsum dolor坐着。（这是用于愚蠢的代码/文本比率控制。）

Answer 1

redisReply是一个类型化对象（请参阅类型字段），多批量回复具有特定类型（REDIS_REPLY_ARRAY）。在这种情况下，str字段不相关。

来自hiredis文档：

The number of elements in the multi bulk reply is stored in reply->elements.
Every element in the multi bulk reply is a redisReply object as well
and can be accessed via reply->element[..index..].
Redis may reply with nested arrays but this is fully supported.

所以你的代码应该改变如下：

reply = redisCommand(redis, "MGET %s %s", "foo", "name" );
if ( reply->type == REDIS_REPLY_ERROR )
  printf( "Error: %s\n", reply->str );
else if ( reply->type != REDIS_REPLY_ARRAY )
  printf( "Unexpected type: %d\n", reply->type );
else 
{
  int i;
  for ( i=0; i<reply->elements; ++i )
    printf( "Result: %s\n", reply->element[i]->str );
}
freeReplyObject(reply);

通过此更改，输出现在为：

SET foo bar: OK
SET name value: OK
Result: bar
Result: value

注意：不需要释放每个单独的元素，因为freeReplyObject删除了整个树。

我可以将MGET与hiredis一起使用吗？

1 个答案: