I have JSON data which looks like this:
[
{
"globalTradeID": 64201000,
"tradeID": 549285,
"date": "2016-11-11 23:51:58",
"type": "buy",
"rate": "10.33999779",
"amount": "0.02176472",
"total": "0.22504715"
},
{
"globalTradeID": 64200631,
"tradeID": 549284,
"date": "2016-11-11 23:48:39",
"type": "buy",
"rate": "10.33999822",
"amount": "0.18211700",
"total": "1.88308945"
}...
]
I've tried to unmarshall this JSON by defining a type:
type TradeHistoryResponse []TradeHistoryInfo
type TradeHistoryInfo struct {
GlobalTradeID int64 `json:"globalTradeID"`
TradeID int64 `json:"tradeID"`
Date string `json:"date"`
Type string `json:"type"`
Rate float64 `json:"rate,string"`
Amount float64 `json:"amount,string"`
Total float64 `json:"total,string"`
}
And then pulling the JSON data as so:
//Read response
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("[Poloniex] (doRequest) Failed to parse response for query to %s! (%s)", reqURL, err.Error())
}
//Convert JSON to struct
var THR TradeHistoryResponse
err = json.Unmarshal(body, &THR)
if err != nil {
return nil, fmt.Errorf("[Poloniex] (doRequest) Failed to convert response into JSON for query to %s! (%s)", reqURL, err.Error())
}
I get the following error:
(json: cannot unmarshal object into Go value of type poloniex.TradeHistoryResponse)
My best guess why the Unmarshall doesn't work is because the array is key-less?
Would love to have some clarification on the matter on how I might best get this working.
I didn't think unmarhsalling an array in a JSON like you intended actually works but to the props of encoding/json it does. Example code: package main
import (
"encoding/json"
"fmt"
"log"
)
var mjs string = "[" +
"{" +
`"globalTradeID": 64201000,
"tradeID": 549285,
"date": "2016-11-11 23:51:58",
"type": "buy",
"rate": "10.33999779",
"amount": "0.02176472",
"total": "0.22504715"
},
{
"globalTradeID": 64200631,
"tradeID": 549284,
"date": "2016-11-11 23:48:39",
"type": "buy",
"rate": "10.33999822",
"amount": "0.18211700",
"total": "1.88308945"
}
]`
type TradeHistoryResponse []TradeHistoryInfo
type TradeHistoryInfo struct {
GlobalTradeID int64 `json:"globalTradeID"`
TradeID int64 `json:"tradeID"`
Date string `json:"date"`
Type string `json:"type"`
Rate float64 `json:"rate,string"`
Amount float64 `json:"amount,string"`
Total float64 `json:"total,string"`
}
func main() {
//Convert JSON to struct
var THR TradeHistoryResponse
err := json.Unmarshal([]byte(mjs), &THR)
if err != nil {
log.Fatal(err)
}
for _, v := range THR {
fmt.Printf("%+v", v)
fmt.Printf("
")
}
}
This prints out all the values as expected. So it doesn't have a problem converting the json values to float/int either (which would have been my second guess).
Are you sure you aren't modifying the Body in any way ? And that the example you give cover all edge cases ?
Could you add:
fmt.Println(string(body))
to the second error block and log the error it give here.
Also what version of go are you using ? I wouldn't exclude the possibility of encoding/json to have changed between versions. In the end, if this is indeed the case the easy fix would be taking your response as a string, removing all whitespaces and splitting at "}'{" as in:
fmtBody := strings.Replace(string(body), "
", "", -1)
fmtBody = strings.Replace(string(fmtBody), "\w", "", -1)
fmtBody = strings.Replace(string(fmtBody), "[", "", -1)
fmtBody = strings.Replace(string(fmtBody), "]", "", -1)
var goArrOfYourJsonsObj []String = strings.Split(fmtBody, "},{")
for k, _ := range goArrOfYourJsonsObj {
goArrOfYourJsonsObj[k] += "}"
}
And now you have your JSON objects neatly separated into a go array of types String which, can be used in Unmarshall as []byte(val).
TradeHistoryResponse is a type no a variable, you have to create a var of type TradeHistoryResponse, like this:
var th TradeHistoryResponse
//Convert JSON to struct
err = json.Unmarshal(body, &th)
// ...
fmt.Printf("%+v
", th)