Multi WATCH in Golang using go-redis/redis - go

Question

I am trying to do this 4 redis calls in one transaction using https://github.com/go-redis/redis :
func getHost(key) host, score, error{
numberOfHosts, err := rdb.ZCard(key).Result()
if err != nil {
return nil, 0, err
}
host, err := rdb.ZRangeByScoreWithScores(key, redis.ZRangeBy{
Min: "0",
Max: strconv.Itoa(maxScore),
Offset: numberOfHosts - 1,
Count: 1,
}).Result()
if err != nil {
return nil, 0, err
}
score := host[0].Score
member, err := json.Marshal(host[0].Member)
if err != nil {
return nil, 0, err
}
if int(score) < maxCapacity {
rdb.ZIncrBy(key, score+1, string(member))
}
host, err := rdb.GetHost(string(member))
if err != nil {
return nil, 0, err
}
return host, int(score), nil
}
I found this https://godoc.org/github.com/go-redis/redis#Client.Watch in the doc and I am trying to do something with it but it is a bit difficult at the moment.
Is anybody already done this and can provide advice ?
EDIT :
I tried to do this :
count := func(key string) error {
txf := func(tx *redis.Tx) error {
numberOfHosts, err := tx.ZCard(key).Result()
if err != nil {
return err
}
numberOfHosts--
_, err = tx.Pipelined(func(pipe redis.Pipeliner) error {
getHostKey := func(key string, numberOfHosts int) error {
txf := func(tx *redis.Tx) error {
host, err := tx.ZRangeByScoreWithScores(key, redis.ZRangeBy{
Min: "0",
Max: strconv.Itoa(maxCapacity),
Offset: numberOfHosts,
Count: 1,
}).Result()
if err != nil {
return err
}
if len(host) == 0 {
return fmt.Errorf("Get Host did not return a host for the key: %v", key)
}
score := host[0].Score
member, err := json.Marshal(host[0].Member)
if err != nil {
return err
}
score++
_, err = tx.Pipelined(func(pipe redis.Pipeliner) error {
if int(score) < maxCapacity {
incScore := func(key string, score int, member string) (*Host, int, error) {
txf := func(tx *redis.Tx) error {
tx.ZIncrBy(key, score, string(member))
host, err := rc.GetHost(string(member))
if err != nil {
return nil, 0, err
}
return host, int(score), nil
}
}
err := rc.Client.Watch(txf, key)
if err != redis.TxFailedErr {
return err
}
}
}
})
}
err := rc.Client.Watch(txf, key)
if err != redis.TxFailedErr {
return err
}
}
if err := getHostKey(key, numberOfHosts); err != nil {
return err
}
})
}
err := rc.Client.Watch(txf, key)
if err != redis.TxFailedErr {
return err
}
}
if err := count(key); err != nil {
return nil, 0, err
But the compiler is not happy with all the variable coming from the previous watch.
I will look into LUA script