This repository was archived by the owner on Dec 15, 2025. It is now read-only.
This repository was archived by the owner on Dec 15, 2025. It is now read-only.
Unable to unmarshal date using json-iterator. #313
Description
I am trying to use a custom struct which implements the json.Unmarshaler interface as a key in a map(map[MyCustomType]bool). This fails when I am trying to use jsoniter but works correctly if I use the standard library json package. Minimal code example to reproduce the issue:
package main
import (
"encoding/json"
"fmt"
"time"
jsoniter "github.com/json-iterator/go"
)
type Date struct {
time.Time
}
func (d *Date) UnmarshalJSON(b []byte) error {
dateStr := string(b) // something like `"2017-08-20"`
if dateStr == "null" {
return nil
}
t, err := time.Parse(`"2006-01-02"`, dateStr)
if err != nil {
return fmt.Errorf("cant parse date: %#v", err)
}
d.Time = t
return nil
}
func main() {
data := []byte(`{
"2018-12-12": true,
"2018-12-13": true,
"2018-12-14": true
}`)
v := map[Date]bool{}
if err := json.Unmarshal(data, &v); err != nil {
panic(fmt.Errorf("standard library unmarshal: %+v", err))
}
fmt.Printf("Unmarshalled value using standard library: %+v\n", v)
if err := jsoniter.Unmarshal(data, &v); err != nil {
panic(fmt.Errorf("jsoniter unmarshal: %+v", err))
}
fmt.Printf("%#v\n", v)
}Output:
Unmarshalled value using standard library: map[2018-12-14 00:00:00 +0000 UTC:true 2018-12-12 00:00:00 +0000 UTC:true 2018-12-13 00:00:00 +0000 UTC:true]
panic: jsoniter unmarshal: textUnmarshalerDecoder: parsing time "2018-12-12" as "2006-01-02T15:04:05Z07:00": cannot parse "" as "T", error found in #10 byte of ...|018-12-12": true,
|..., bigger context ...|{
"2018-12-12": true,
"2018-12-13": true,
"2018-|...