golang reflect for sql scan 报错

Question

/**-- name is character varying(64)CREATE TABLE users(  id bigint NOT NULL,  no character(24),  identity name,  name name,  head character varying(256),  email character varying(256),  site character varying(256),  create_time timestamp without time zone,  city_id bigint,  timezone jsonb,  update_time timestamp without time zone,  CONSTRAINT user__pk PRIMARY KEY (id))spottly=# SELECT "id", "no", "identity", "name", "head", "email", "site", "create_time", "city_id", "update_time", "timezone" FROM "users" WHERE "email" = '[e-mail]' LIMIT 1 OFFSET 0;       id       | no | identity |  name   |                  head                  |      email       |            site            | create_time | city_id | update_time | timezone----------------+----+----------+---------+----------------------------------------+------------------+----------------------------+-------------+---------+-------------+---------- 95083655397376 |    | fixopen  | fixopen | /uploader/52e2762edf4e633666000867.png | [e-mail] | http://spottly.com/fixopen |             |         |             |(1 row)*/package mainimport (    "database/sql"    //"errors"    "fmt"    _ "github.com/lib/pq"    "log"    "net/url"    "reflect"    "strings"    "time")type User struct {    Id          uint64    `json:"id"`    No          *string   `json:"no"`    Identity    string    `json:"identity"`    Name        string    `json:"name"`    Head        url.URL   `json:"head"`    Email       *string   `json:"email"`    Site        url.URL   `json:"site"`    Create_time time.Time `json:"create-time"`    City_id     *uint64   `json:"city-id"`    Update_time time.Time `json:"update-time"`    Timezone    *string   `json:"timezone"`}func main() {    connectionString := "host=localhost port=5432 user=postgres dbname=spottly password=123456 sslmode=disable"    db, err := sql.Open("postgres", connectionString)    defer db.Close()    if err != nil {        log.Fatal(err)    }

Answer 1

url.URL没有实现sql.Scanner，所以它不能从数据库扫描。您可以制作一个确实实现的包装器类型sql.Scanner：

type sqlURL struct { url.URL }

func (su *sqlURL) Scan(v interface{}) error {

    u, err := url.Parse(string(v.([]byte)))

    if err != nil {

        return err

    }

    *su = sqlURL{*u}

    return nil

}

或者将URL单独扫描成字符串然后解析：

var urlStr string

err = db.QueryRow(command).Scan(/* ... */, &urlStr)

// check err

u, err := url.Parse(urlStr)

// check err

user.Site = *u