HMGET: Empty result when passing params

Question

Using redigo, I'm trying to use HMGET. I'm passing a string slice as param in field. It is not working, returning empty result.

func HMGET(c redis.Conn, field []string)(){
        if err := c.Send("HMGET", HashName, field); err != nil {
            return nil, err
        }
        if err := c.Flush(); err != nil {
            return nil, err
        }
        rval, err := c.Receive()
        if err != nil {
            return nil, err
        }
        return rval, nil
}

This is working

c.Send("HMGET", r.HashName, "1", "2", "3")

Any suggestions why field when passed as param is not working?

JimB · Accepted Answer · 2016-12-05T14:07:26.057

2

What you're sending is HMGET r.HashName [1 2 3]

Separate the arguments or add them the same slice and expand that slice as the variadic parameter. Since you're using type []string you will need to convert that to an []interface{} type as well:

func HMGET(c redis.Conn, field []string) {
    args := make([]interface{}, len(field)+1)
    args[0] = HashName
    for i, v := range field {
        args[i+1] = v
    }

    if err := c.Send("HMGET", args...); err != nil {
        return nil, err
    }
    //////

edited Dec 05 '16 at 14:07

answered Dec 05 '16 at 13:53

JimB

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the signature is `Send(cmd string, args ...interface{}) error`. so you need to convert to an interface{} slice first. – Not_a_Golfer Dec 05 '16 at 13:56
@Not_a_Golfer: oops, should have double-checked the docs ;) will fix. – JimB Dec 05 '16 at 14:01
Now in result I'm getting ["val1", "val2", "val3" ], how do I get it in [ "val:pair" ] format? – Ankit Deshpande Dec 05 '16 at 14:02
@AnkitDeshpande: do you want the [StringMap](https://godoc.org/github.com/garyburd/redigo/redis#StringMap) function? – JimB Dec 05 '16 at 14:06
@Not_a_Golfer so can I assume that the order of result is the same as that of input ? – Ankit Deshpande Dec 05 '16 at 14:07
@JimB I tried using StringMap function but is says need even no of arguments – Ankit Deshpande Dec 05 '16 at 14:07
@AnkitDeshpande: yes, that is for fetching the entire hash. If you just want specific fields, that you need to do it manually as Not_a_Golfer said. – JimB Dec 05 '16 at 14:09

HMGET: Empty result when passing params

1 Answers1