encjsongen

encoding/json generator for custom JSON marshalling.

Install

go get -u github.com/daisuzu/encjsongen

Usage

encjsongen: Generate MarshalJSON() and UnmarshalJSON() from customjson tag.
	Tag format => customjson:"NAME=EXPR;ASSIGN"
	    - NAME: Used in place of json tag
	    - EXPR: Expression to represent alias type(for MarshalJSON)
	    - ASSIGN: Expression to assign to the actual type(for UnmarshalJSON)
	Note: "$" in EXPR and ASSIGN is a special character that is converted to
	      the field name with receiver on the right hand side.
	
	// Example:
	type v struct {
		CreateTime time.Time `json:"-" customjson:"createTime=$.Unix();time.Unix($, 0)"`
	}


Usage: encjsongen [-flag] [package]

Example(by @omohayui)

• user.go

package user

import (
	"regexp"
	"strings"
	"time"
)

type User struct {
	ID        int64     `json:"id"`
	Name      string    `json:"name"`
	StartTime time.Time `json:"-" customjson:"createTime=$.Unix();time.Unix($, 0)"`
	Text      string    `json:"-" customjson:"text=lineBreak($);unlineBreak($)"`
	Password  string    `json:"-" customjson:"password=mask($);unmask($)"`
}

var rx = regexp.MustCompile(`[\r\n]`)

func lineBreak(s string) string {
	return rx.ReplaceAllString(s, "<br>")
}

func unlineBreak(s string) string {
	return strings.Replace(s, "<br>", "\n", -1)
}

func mask(s string) string {
	// TODO
	return ""
}

func unmask(s string) string {
	// TODO
	return ""
}

• user_json.go

// Code generated by encjsongen. DO NOT EDIT.

package user

import (
	"encoding/json"
	"time"
)

func (v *User) MarshalJSON() ([]byte, error) {
	type Alias User
	return json.Marshal(&struct {
		*Alias
		AliasStartTime int64  `json:"createTime"`
		AliasText      string `json:"text"`
		AliasPassword  string `json:"password"`
	}{
		Alias:          (*Alias)(v),
		AliasStartTime: v.StartTime.Unix(),
		AliasText:      lineBreak(v.Text),
		AliasPassword:  mask(v.Password),
	})
}

func (v *User) UnmarshalJSON(b []byte) error {
	type Alias User
	aux := &struct {
		*Alias
		AliasStartTime int64  `json:"createTime"`
		AliasText      string `json:"text"`
		AliasPassword  string `json:"password"`
	}{
		Alias: (*Alias)(v),
	}
	if err := json.Unmarshal(b, &aux); err != nil {
		return err
	}
	v.StartTime = time.Unix(aux.AliasStartTime, 0)
	v.Text = unlineBreak(aux.AliasText)
	v.Password = unmask(aux.AliasPassword)
	return nil
}