add example

_example/json/json.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"encoding/json"
+	"fmt"
+	_ "github.com/mattn/go-sqlite3"
+	"log"
+	"os"
+)
+
+type Tag struct {
+	Name    string `json:"name"`
+	Country string `json:"country"`
+}
+
+func (t *Tag) Scan(value interface{}) error {
+	return json.Unmarshal([]byte(value.(string)), t)
+}
+
+func (t *Tag) Value() (driver.Value, error) {
+	b, err := json.Marshal(t)
+	return string(b), err
+}
+
+func main() {
+	os.Remove("./foo.db")
+
+	db, err := sql.Open("sqlite3", "./foo.db")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer db.Close()
+
+	_, err = db.Exec(`create table foo (tag jsonb)`)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	stmt, err := db.Prepare("insert into foo(tag) values(?)")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer stmt.Close()
+	_, err = stmt.Exec(`{"name": "mattn", "country": "japan"}`)
+	if err != nil {
+		log.Fatal(err)
+	}
+	_, err = stmt.Exec(`{"name": "michael", "country": "usa"}`)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var country string
+	err = db.QueryRow("select tag->>'country' from foo where tag->>'name' = 'mattn'").Scan(&country)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(country)
+
+	var tag Tag
+	err = db.QueryRow("select tag from foo where tag->>'name' = 'mattn'").Scan(&tag)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println(tag.Name)
+
+	tag.Country = "日本"
+	_, err = db.Exec(`update foo set tag = ? where tag->>'name' == 'mattn'`, &tag)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = db.QueryRow("select tag->>'country' from foo where tag->>'name' = 'mattn'").Scan(&country)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(country)
+}