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https://github.com/mattn/go-nulltype

Null friendly types
https://github.com/mattn/go-nulltype

database go golang json null nullable

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Null friendly types

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# go-nulltype

[![Build Status](https://travis-ci.org/mattn/go-nulltype.svg?branch=master)](https://travis-ci.org/mattn/go-nulltype)
[![codecov](https://codecov.io/gh/mattn/go-nulltype/branch/master/graph/badge.svg)](https://codecov.io/gh/mattn/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

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

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

### friendly to Stringer

```go
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

```go
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

```go
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

```go
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](https://github.com/go-gorp/gorp).

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

```go
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