segmentio/encoding

json.Unmarshaler difference: UnmarshalJSON([]byte("null")) skipped

efepapa opened this issue · 1 comments

efepapa commented

Go 1.14.8 linux/amd64

v0.1.15 does not use my custom UnmarshalJSON() for []byte("null")

Documentation says:

By convention, to approximate the behavior of Unmarshal itself, Unmarshalers implement UnmarshalJSON([]byte("null")) as a no-op.

encoding/json calls it, github.com/segmentio/encoding/json skips it.

package main

import (
	//"encoding/json"
	"fmt"
	"github.com/segmentio/encoding/json"
)

type RawJsonString string

func (r *RawJsonString) UnmarshalJSON(b []byte) error {
	fmt.Printf("UnmarshalJSON: %s\n", string(b))
	if len(b) == 0 {
		*r = "null"
	} else {
		*r = RawJsonString(b)
	}
	return nil
}

func main() {
	var out RawJsonString
	if err := json.Unmarshal([]byte("null"), &out); err != nil {
		panic(err)
	}
	fmt.Printf("out = %#v\n", out)
}

encoding/json:

  UnmarshalJSON: null
  out = "null"

github.com/segmentio/encoding/json:

  out = ""