How do I convert this cache item back to a slice of maps?

Question

I'm still new to Go and trying to use Beego's cache. I can put a []map[string]string into the cache but can't figure out how to convert the value back to a []map[string]string.

For instance, to put the item in the cache:

m:=make([]map[string]string)
// add items to the slice of maps
.......
// cache it
if err := c.Put("key", m, 100); err != nil {
    fmt.Println(err)
}
// retrieve it
n := c.Get("key")
fmt.Println(reflect.TypeOf(n)) // ==>string

// failed attempt
a := n.([]map[string]string)
fmt.Println(a) // panic: interface conversion: interface is string, not []map[string]string

How do I convert n to a slice of maps?

Answer 1

well digging into the code seems like even if it says interface{} what it does it actually squash everything to []byte

https://github.com/astaxie/beego/blob/master/cache/memcache/memcache.go#L77

and when it Does the Get convert everything to string

https://github.com/astaxie/beego/blob/master/cache/memcache/memcache.go#L61

So you need to Marshal / Unmarshal the data structure yourself.

See this example and substitute your calls and error check with the dummies one provided:

http://play.golang.org/p/9z3KcOlgAx

package main

import (
    "bytes"
    "encoding/json"
    "log"
)

var cache map[string]string = make(map[string]string)

func Put(key, value string) {
    cache[key] = value
}

func Get(key string) string {
    return cache[key]
}

func main() {

    m := map[string]string{
        "A": "1",
        "B": "2",
    }
    if b, err := json.Marshal(m); err != nil {
        log.Fatal(err)
    } else {
        Put("myKey", string(b))
    }

    b := bytes.NewBufferString(Get("myKey"))

    var mm map[string]string
    if err := json.Unmarshal(b.Bytes(), &mm); err != nil {
        log.Fatal(err)
    }

    log.Printf("%#v", mm)
}