Golang用一个字符串和一个float64将JSON解码为切片

I am running a query on a database that I have on a sever. The problem is when I am trying to decode the JSON into a 2D slice I get an error because one of them elements is a string and the other element is a float64.

One way I tried to resolve this issue is my modifying the JSON string before I decode it by adding quotes to make the number a string. But is there a better way of doing this? Is there a way I can modify the struct of my code where I am able to decode the JSON code?

2018/05/04 12:32:19 json: cannot unmarshal number into Go struct field .values of type string

import (
"fmt"
"encoding/json"
"strings"
"io"
"log"
)

func main(){
    str := "{\"results\":[{\"statement_id\":0,\"series\":[{\"name\":\"_\",\"columns\":[\"time\",\"last\"],\"values\":[[\"2018-03-20T18:45:57.07Z\",142774272]]}]}]}"

    type Response struct {
        Results []struct {
            StatementID int `json:"statement_id"`
            Series []struct {
                Name string `json:"name"`
                Columns []string `json:"columns"`
                Values [][]string `json:"values"`
            } `json:"series"`
        } `json:"results"`
    }

    dec := json.NewDecoder(strings.NewReader(str))
        for {
            var m Response
            if err := dec.Decode(&m); err == io.EOF {
                break
            } else if err != nil {
                log.Fatal(err)
            }
            fmt.Println(m.Results[0].Series[0].Values[0])
        }
    }

This is a really unfortunate API to have to work with, but there is a (somewhat clumsy) workaround:

Values [][]interface{} `json:"values"`

Basically this is saying "an array of things of unknown type". This will allow the decoder to decode properly, but it will require you to do some type assertions to actually use the values, in order to get from "unknown type" to a known type that you can actually use:

strVal := m.Results[0].Series[0].Values[0][0].(string)
floatVal := m.Results[0].Series[0].Values[0][1].(float64)

Runnable example: https://play.golang.org/p/ikIHnXlSlYx