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
