golang自己定义数据类型查询与插入postgresql中point数据

详细代码例如以下：

package main

import (
    "bytes"
    "database/sql"
    "database/sql/driver"
    "fmt"
    _ "github.com/lib/pq"
    "strconv"
    "strings"
)

// 自己定义支持类型
type Point struct {
    X float64 `json:"lat"`
    Y float64 `json:"lng"`
}
// 实现driver.Valuer接口
func (p *Point) Value() (driver.Value, error) {
    buf := new(bytes.Buffer)
    fmt.Fprintf(buf, "(%f %f)", p.X, p.Y)
    return buf.Bytes(), nil
}

func (p *Point) String() string {
    return fmt.Sprintf("(%v %v)", p.X, p.Y)
}
// 实现sql.Scanner接口
func (p *Point) Scan(val interface{}) (err error) {
    if bb, ok := val.([]uint8); ok {
        tmp := bb[1 : len(bb)-1]
        coors := strings.Split(string(tmp[:]), ",")
        if p.X, err = strconv.ParseFloat(coors[0], 64); err != nil {
            return err
        }
        if p.Y, err = strconv.ParseFloat(coors[1], 64); err != nil {
            return err
        }
    }
    return nil
}

type Agent struct {
    Id         int    `json:"id"`
    Name       string `json:"name"`
    Code       string `json:"code"`
    CS_NO      string `json:"cs_no"`
    Channel_id int    `json:"channel_id"`
    Address    string `json:"address"`
    Coordinate *Point `json:"point"`
}

func main() {
    pgurl := fmt.Sprintf("postgres://%s:%s@%s:%s/%s?sslmode=disable", "postgres", "123456", "localhost", "5432", "people")

    db, err := sql.Open("postgres", pgurl)
    if err != nil {
        panic(fmt.Errorf("连接数据库出错:%v", err))
    }

    querySql := `SELECT * FROM t_agent`
    rows, err := db.Query(querySql)
    if err != nil {
        panic(fmt.Errorf("查询数据出错:%v", err))
    }

    for rows.Next() {
        agent := &Agent{Coordinate: &Point{}}
        err = rows.Scan(&agent.Id,
            &agent.Name, &agent.Code,
            &agent.CS_NO, &agent.Channel_id,
            &agent.Address, agent.Coordinate)
        fmt.Println(agent, err)
    }
    var id int
    err = db.QueryRow("INSERT INTO t_agent (name, code, cs_no, address, coordinate) VALUES($1,$2,$3,$4,$5) RETURNING id",
        "test1", "123457", "2", "111", "(12,43)").Scan(&id)

    fmt.Println("id:", id, "err:", err)
}

字段类型须要支持查询的scan时，须要实现sql.Scanner接口
字段类型须要支持插入时，须要实现driver.Valuer接口