golang json数组解组为struct类型
[英]golang json array unmarshal into type struct
问题描述
What is causing this to not break apart json? 
是什么导致这不分解json？ Anyone have an idea on how type is wrong? 任何人都有关于类型错误的想法吗？
With error of: 错误为：
{"Rates":[{"Symbol":"EURAUD","Bid":"1.45492","Ask":"1.45608","Spread":"11.60","ProductType":"1",},{"Symbol":"Copper","Bid":"2.6068","Ask":"2.6088","Spread":"2.00","ProductType":"3",},{"Symbol":"AUDNZD","Bid":"1.08999","Ask":"1.09177","Spread":"17.80","ProductType":"1",},{"Symbol":"EURSEK","Bid":"9.63786","Ask":"9.65569","Spread":"178.30","ProductType":"1",},{"Symbol":"CADJPY","Bid":"81.629","Ask":"81.708","Spread":"7.90","ProductType":"1",},{"Symbol":"USDCHF","Bid":"0.99463","Ask":"0.99527","Spread":"6.40","ProductType":"1",},{"Symbol":"USDCNH","Bid":"6.8973","Ask":"6.8993","Spread":"20.00","ProductType":"1",},{"Symbol":"US30","Bid":"20950.00","Ask":"20952.00","Spread":"2.00","ProductType":"2",},{"Symbol":"XAGUSD","Bid":"17.202","Ask":"17.25","Spread":"4.80","ProductType":"5",},{"Symbol":"USDSEK","Bid":"8.84794","Ask":"8.85542","Spread":"74.80","ProductType":"1",},{"Symbol":"AUDCHF","Bid":"0.74417","Ask":"0.74588","Spread":"17.10","ProductType":"1",},{"Symbol":"GER30","Bid":"12431.05",
panic: json: cannot unmarshal string into Go value of type main.MsgRatesArray
goroutine 1 [running]:
main.main()
/tmp/test.go:50 +0x52c
With this code: 使用此代码：
package main
import (
"log"
"fmt"
"net/http"
"bytes"
"io/ioutil"
"strings"
"github.com/pquerna/ffjson/ffjson"
)
type MsgRatesArray struct {
RateQuote []MsgRateQuoteJson `json:"Rates"`
}
type MsgRateQuoteJson struct {
SymbolName string `json:"Symbol"`
SymbolBid int64 `json:"Bid"`
SymbolAsk int64 `json:"Ask"`
SymbolSpread int64 `json:"Spread"`
SymbolPT string `json:"ProductType"`
}
var respBytes []byte
func main() {
var msg MsgRatesArray
response,err := http.Get("https://ratesjson.fxcm.com/DataDisplayer")
if err != nil {
log.Fatal(err)
}
defer response.Body.Close()
respBytes, err := ioutil.ReadAll(response.Body)
//Get bad JSON into string
jsonBytes := respBytes[bytes.Index(respBytes, []byte("{")):bytes.LastIndex(respBytes, []byte("}"))+1]
jsonString := string(jsonBytes)
fmt.Println(jsonString)
// Use a positive number to indicate max replacement count to fix bad JSON string so we can remove comma in JSON ARRAY.
result := strings.Replace(jsonString, "\",}", "\"}", -1)
fmt.Println(result)
// Turn GOOD JSON string back to JSON BYTES (BIN)
jsonBytes2, err := ffjson.Marshal(result)
if err != nil {
panic(err)
}
// Parse JSON !
err = ffjson.Unmarshal(jsonBytes2, &msg)
if err != nil {
panic(err)
}
}
What is wrong with type for json array? json数组的类型有什么问题？
1 个解决方案
解决方案1
2 已采纳 2017-04-29 20:49:34
In the returned json Bid , Ask , and Spread are json strings not integers, so change your type definition to this: 在返回的json Bid ， Ask和Spread是json字符串而不是整数，因此将类型定义更改为：
type MsgRateQuoteJson struct {
SymbolName string `json:"Symbol"`
SymbolBid string `json:"Bid"`
SymbolAsk string `json:"Ask"`
SymbolSpread string `json:"Spread"`
SymbolPT string `json:"ProductType"`
}
And marshaling a json string to get json bytes is not the correct way, just convert the string to a byte slice like this: 封送json字符串以获取json字节不是正确的方法，只需将字符串转换为如下所示的字节片：
jsonBytes2 := []byte(result)
... and you're good to go: ...而且您很高兴：
// Parse JSON !
err = ffjson.Unmarshal(jsonBytes2, &msg)
if err != nil {
panic(err)
}
Edit : 编辑 ：
If you want to convert those strings into specific types during the json unmarshaling, you can do so by defining an UnmarshalJSON method on the *MsgRateQuoteJson type, plus with the help of the strconv package, like this: 如果要在json解组期间将这些字符串转换为特定类型，可以通过在*MsgRateQuoteJson类型上定义UnmarshalJSON方法，并借助strconv包来实现，例如：
type MsgRateQuoteJson struct {
SymbolName string `json:"Symbol"`
SymbolBid float64 `json:"Bid"`
SymbolAsk float64 `json:"Ask"`
SymbolSpread float64 `json:"Spread"`
SymbolPT int64 `json:"ProductType"`
}
func (msg *MsgRateQuoteJson) UnmarshalJSON(data []byte) (err error) {
m := map[string]string{}
if err = ffjson.Unmarshal(data, &m); err != nil {
return err
}
msg.SymbolName = m["Symbol"]
if msg.SymbolBid, err = strconv.ParseFloat(m["Bid"], 64); err != nil {
return err
}
if msg.SymbolAsk, err = strconv.ParseFloat(m["Ask"], 64); err != nil {
return err
}
if msg.SymbolSpread, err = strconv.ParseFloat(m["Spread"], 64); err != nil {
return err
}
if msg.SymbolPT, err = strconv.ParseInt(m["ProductType"], 10, 64); err != nil {
return err
}
return nil
}
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