go-nulltype

Nullable types friendly to json.Encoder, json.Decoder, database/sql, fmt.Stringer, text/template, html/template, some of ORMs.

Supported types:

• NullBool
• NullString
• NullFloat64
• NullInt64
• NullTime

Usage

import "github.com/mattn/go-nulltype"

type User struct {
	Name	nulltype.NullString `json:"name"`
}

friendly to Stringer

var user User
fmt.Println(user.Name.Valid()) // false
fmt.Println(user.Name) // ""

user.Name.Set("Bob")
fmt.Println(user.Name.Valid()) // true
fmt.Println(user.Name) // "Bob"

fmt.Println(user.Name.StringValue() == "Bob") // true

user.Name.Reset()
fmt.Println(user.Name.Valid()) // false
fmt.Println(user.Name) // ""

friendly to json.MarshalJSON

var user User
fmt.Println(user.Name.Valid()) // false
json.NewEncoder(os.Stdout).Encode(user) // {"name": null}

user.Name.Set("Bob")
fmt.Println(user.Name.Valid()) // true
json.NewEncoder(os.Stdout).Encode(user) // {"name": "Bob"}

friendly to json.UnmarshalJSON

var user User
s := `{"name": "Bob"}`
json.NewDecoder(strings.NewReader(s)).Decode(&user)
fmt.Println(user.Name.Valid()) // true
fmt.Println(user.Name) // "Bob"

s = `{"name": null}`
json.NewDecoder(strings.NewReader(s)).Decode(&user)
fmt.Println(user.Name.Valid()) // false
fmt.Println(user.Name) // ""

friendly to database/sql

var user User
db.QueryRow(`SELECT name FROM users`).Scan(&user.Name)
fmt.Println(user.Name.Valid()) // true or false
fmt.Println(user.Name) // "Bob" or ""
db.Exec(`INSERT INTO users(name) VALUES($1)`, user.Name)

friendly to ORM

Struct tag with gorp.

type Post struct {
	Id      int64 `db:"post_id"`
	Created int64
	Title   string              `db:",size:50"`
	Body    nulltype.NullString `db:"body,size:1024"`
}

p := Post{
	Created: time.Now().UnixNano(),
	Title:   title,
	Body:    nulltype.NullStringOf(body),
}
err = dbmap.Insert(&p)

Installation

go get github.com/mattn/go-nulltype

License

MIT

Author

Yasuhiro Matsumoto