How fix Issue in Struct using Go?

Question

I have Problem in Struct using Go.

example code:

package main
import (
    "fmt"
)    
type KeyVal struct {
    Key   interface{}
    Value interface{}
}
type KeyVals []KeyVal
func (kvs *KeyVals) AddOld(key interface{}, val interface{}) {
    kv := KeyVal{key, val,typ}
    *kvs = append(*kvs, kv)
}
func (kvs *KeyVals) Add(key interface{}, val interface{}){
    var flag,id = kvs.Exist(key)
    if flag == true {
        //kv := KeyVal{key,"Updated!"}
        //*kvs=append(*kvs,kv)
        //fmt.Println(*kvs[0].Key)
        //update value of them
        kv := KeyVal{key,val}
        kvs[id]=kv
        //*kvs[id]=kv
        //fmt.Println("old set with id =",id,",","value =",kvs)
    }else{
        kv := KeyVal{key, val}
        *kvs = append(*kvs, kv)
    }
}
func (kvs *KeyVals) Search(skey interface{}) (bool,interface{},interface{}) {
    for n, kv := range *kvs {
        key := kv.Key
        val := kv.Value
        if(key == skey){
            return true,n,val
        }
    }
    return false,nil,nil
}
func (kvs *KeyVals) Exist(skey interface{})(bool,int) {
    for n, kv := range *kvs {
        key := kv.Key
        if(key == skey){
            return true,n
        }
    }
    return false,-1
}
func main() {
    var kvs keyval.KeyVals

    kvs.Add("key1","value1")
    kvs.Add("key2","value2")
    kvs.Add("key3","value3")
    kvs.Add("key4",5)
    kvs.Add("key5",5.2)
    kvs.Add("key5","new....")//this should update value of this key. but not work!


var flag,id,value = kvs.Search("key5")
fmt.Println(flag,id,value)


    for _, kv := range kvs {
        key := kv.Key
        val := kv.Value

        fmt.Println("", key," ==> ", val)
    }
}

Problem of me:

1. in function Add() , kvs[id]=kv have error! how fix?

2. speed of Exist() and Search() is good? can not make better?

3. I try add index name to code : type KeyVals []KeyVal change to : mean : type KeyVals [interface{}]KeyVal or type KeyVals [string]KeyVal ... but error!

Answer 1

1 . in function Add() , kvs[id]=kv have error! how fix?

kvs is of type *KeyVals it does not support indexing You may use

(*kvs)[id] = kv 

2 . speed of Exist() and Search() is good? can not make better?

You may use a hashmap instead of array for faster search/exist functions.You can combine search and exist to one function.

3 . i try add index name to code : type KeyVals []KeyVal change to : mean : type KeyVals [interface{}]KeyVal or type KeyVals [string]KeyVal ... but error!

The type declarations are wrong.Types closer to those are map[interface{}]interface{} or map [string]interface{}

Here is the updated code that works, I have used Hashmap instead of array and an array to keep track of the order

Code

package main

import (
    "fmt"
)

type KeyVals struct {
    keyVals     map[string]interface{}
    KeysInOrder []string
}

func (kvs *KeyVals) Add(key string, val interface{}) {
    if kvs.keyVals == nil {
        kvs.keyVals = make(map[string]interface{})
    }
    if _, ok := kvs.keyVals[key]; ok {
        kvs.keyVals[key] = val
        return
    }
    kvs.keyVals[key] = val
    kvs.KeysInOrder = append(kvs.KeysInOrder, key)
    return
}

func (kvs KeyVals) Search(key string) (interface{}, bool) {
    val, found := kvs.keyVals[key]
    return val, found
}

func main() {
    var kvs KeyVals
    kvs.Add("key1", "value1")
    kvs.Add("key2", "value2")
    kvs.Add("key3", "value3")
    kvs.Add("key4", 5)
    kvs.Add("key5", 5.2)
    kvs.Add("key5", "new....") //this should update value of this key. but not work!

    value, ok := kvs.Search("key5")
    fmt.Println(value, ok)

    for _, key := range kvs.KeysInOrder {
        value, _ = kvs.Search(key)
        fmt.Println(key, " ==> ", value)
    }
}

Here is the play link : link