[英]What is a good way to handle single or array struct in golang json.Unmarshal?
我正在使用Go和Yahoo API構建股票報價網絡應用。
問題是如何在不編寫另一個結構的情況下在數組和單個結構之間切換。 我不確定如何用語言解釋它。 這是示例:
從Yahoo API獲得一個符號引號如下所示:
{"query":{"count":1,"created":"2016-05-11T02:12:33Z","lang":"en-US","results":{"quote":{"Change":"+0.21","DaysLow":"9.32","DaysHigh":"9.68","Name":"Alcoa Inc. Common Stock","Open":"9.56","PreviousClose":"9.46","Symbol":"aa","Volume":"22266533","PercentChange":"+2.22%"}}}}
從Yahoo API獲取多個報價:
{"query":{"count":2,"created":"2016-05-11T02:17:48Z","lang":"en-us","results":{"quote":[{"Change":"+0.21","DaysLow":"9.32","DaysHigh":"9.68","Name":"Alcoa Inc. Common Stock","Open":"9.56","PreviousClose":"9.46","Symbol":"aa","Volume":"22266533","PercentChange":"+2.22%"},{"Change":"+0.63","DaysLow":"92.11","DaysHigh":"93.57","Name":"Apple Inc.","Open":"93.35","PreviousClose":"92.79","Symbol":"aapl","Volume":"33686836","PercentChange":"+0.68%"}]}}}
不同之處在於引號成為一個數組[]
。
使用json.Unmarshal(quoteResultRawJSON, &queryResult)
時如何處理?
我的結構看起來像:
type QueryResult struct {
Id bson.ObjectId `bson:"_id,omitempty"`
Query Query `json:"query"`
}
type Query struct {
Count int `json:"count"`
Created string `json:"created"`
Lang string `json:"lang"`
Results Quote `json:"results"`
}
type Quote struct {
Quote StockQuote `json:"quote"` //Here is the difference. Do I need to re-write the whole struct in order to handle []
}
type StockQuote struct {
Change string `json:"change"`
PercentChange string `json:"percentChange"`
DaysLow string `json:"daysLow"`
DaysHigh string `json:"daysHigh"`
Open string `json:"open"`
PreviousClose string `json:"previousClose"`
Symbol string `json:"symbol"`
Name string `json:"name"`
Volume string `json:"volume"`
}
我是否需要編寫另一個結構來處理數組?
使用UnmarshalJSON()
重寫控制解UnmarshalJSON()
過程。
https://play.golang.org/p/pCSgymQYC3
package main
import (
"log"
"encoding/json"
"bytes"
)
const(
s1=`{"query":{"count":1,"created":"2016-05-11T02:12:33Z","lang":"en-US","results":{"quote":{"Change":"+0.21","DaysLow":"9.32","DaysHigh":"9.68","Name":"Alcoa Inc. Common Stock","Open":"9.56","PreviousClose":"9.46","Symbol":"aa","Volume":"22266533","PercentChange":"+2.22%"}}}}`
s2=`{"query":{"count":2,"created":"2016-05-11T02:17:48Z","lang":"en-us","results":{"quote":[{"Change":"+0.21","DaysLow":"9.32","DaysHigh":"9.68","Name":"Alcoa Inc. Common Stock","Open":"9.56","PreviousClose":"9.46","Symbol":"aa","Volume":"22266533","PercentChange":"+2.22%"},{"Change":"+0.63","DaysLow":"92.11","DaysHigh":"93.57","Name":"Apple Inc.","Open":"93.35","PreviousClose":"92.79","Symbol":"aapl","Volume":"33686836","PercentChange":"+0.68%"}]}}}`
)
type QueryResult struct {
//Id bson.ObjectId `bson:"_id,omitempty"`
Query Query `json:"query"`
}
type Query struct {
Count int `json:"count"`
Created string `json:"created"`
Lang string `json:"lang"`
Results Quote `json:"results"`
}
type structOrArray struct{
parent *Quote
s StockQuote
a []StockQuote
}
func (this *structOrArray)UnmarshalJSON(data []byte) error{
d := json.NewDecoder(bytes.NewBuffer(data))
t, err := d.Token();
if err != nil{
return err
}
if t==json.Delim('['){
if err := json.Unmarshal(data, &this.a);err != nil {
return err
}
return nil
}
if err := json.Unmarshal(data, &this.s);err != nil {
return err
}
return nil
}
type fakeQuote struct{
Load structOrArray `json:"quote"` //Here is the difference. Do I need to re-write the whole struct in order to handle []
}
type Quote struct {
Quote *StockQuote
Quotes []StockQuote
}
func (this *Quote)UnmarshalJSON(data []byte) error{
fq := fakeQuote{}
if err := json.Unmarshal(data, &fq);err != nil{
return err
}
this.Quote = &fq.Load.s
this.Quotes = fq.Load.a
return nil
}
type StockQuote struct {
Change string `json:"change"`
PercentChange string `json:"percentChange"`
DaysLow string `json:"daysLow"`
DaysHigh string `json:"daysHigh"`
Open string `json:"open"`
PreviousClose string `json:"previousClose"`
Symbol string `json:"symbol"`
Name string `json:"name"`
Volume string `json:"volume"`
}
func main() {
r := QueryResult{}
err := json.Unmarshal([]byte(s1), &r)
if err != nil {
log.Fatalln(err)
}
log.Println(r.Query.Results.Quote)
log.Println(r.Query.Results.Quotes)
err = json.Unmarshal([]byte(s2), &r)
if err != nil {
log.Fatalln(err)
}
log.Println(r.Query.Results.Quote)
log.Println(r.Query.Results.Quotes)
}
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