使用Golang无法从具有MySQL后端的大猩猩/会话中获得价值

Question

I am trying to save a struct for my model in gorilla sessions with a mySQL backend but only get 0 for venueID when I try to retrieve it. I have no trouble saving and getting flash messages. My goal is to save the model struct in the session and retrieve it to get the id number in edit, update and delete functions.

Here is my code:

type appResource struct {
    tmpl  *template.Template // net/http
    store *mysqlstore.MySQLStore
    db    *sql.DB // database/sql
}

// newAppResource function to pass global var
func newAppResource(store *mysqlstore.MySQLStore, db *sql.DB, tmpl *template.Template) *appResource {
    return &appResource{
        store: store,
        db:    db,
        tmpl:  tmpl,
    }
}

func main() {

sessionKey := os.Getenv("sessionKey")

    endpoint := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?parseTime=true&loc=Local", dbUser, dbPass, dbHost, dbPort, dbName)
    tableName := "sessions"
    path := "/"
    maxAge := 3600
    codecs := []byte(sessionKey)

    store, err := mysqlstore.NewMySQLStore(endpoint, tableName, path, maxAge, codecs)
    if err != nil {
        log.Println("SESSIONS STORE error")
        log.Fatal(err)
....
    }

}


type Venue struct {
    VenueID int
    Name    string
    Email   string
    Phone   string
    Active  bool
}

// VenueData template variable for show and edit
type VenueData struct {
    Venue   Venue
    Flashes []interface{}
}

func (rs *appResource) venuesShow(w http.ResponseWriter, r *http.Request) {

    var venue Venue

    var data VenueData

    id := r.URL.Query().Get("id")

    venueID, err := strconv.Atoi(id)
    if err != nil {
        log.Println("show venue ID not > 0")
        http.Redirect(w, r, "/login", http.StatusUnauthorized)
        return
    }

    if !(venueID > 0) {
        log.Println("update venue ID not > 0")
        http.Redirect(w, r, "/login", http.StatusUnauthorized)
        return
    }

    query, err := rs.db.Query("SELECT id, name, email, phone, active FROM Venues WHERE id=?", venueID)
    if err != nil {
        log.Fatal(err)
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    for query.Next() {

        err = query.Scan(&venue.VenueID, &venue.Name, &venue.Email, &venue.Phone, &venue.Active)
        if err != nil {
            log.Fatal(err)
            http.Error(w, err.Error(), http.StatusInternalServerError)
            return
        }
    }

    data.Venue = venue

    session, err := rs.store.Get(r, "admin-data")
    if err != nil {
        log.Fatal(err)
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    log.Println(venue.VenueID)

    if flashes := session.Flashes(); len(flashes) > 0 {
        for _, message := range flashes {
            data.Flashes = append(data.Flashes, message)
        }
    }

    session.Values["venue"] = venue

    session.Save(r, w)
    if err != nil {
        log.Fatal(err)
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    if err := rs.tmpl.ExecuteTemplate(w, "venues-show", data); err != nil {
        log.Fatal(err)
        http.Error(w, err.Error(), http.StatusInternalServerError)
    }
}


func (rs *appResource) venuesEdit(w http.ResponseWriter, r *http.Request) {

    var data VenueData

    session, err := rs.store.Get(r, "admin-data")
    if err != nil {
        log.Fatal(err)
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    venue := getVenue(session)

    venueID := venue.VenueID

    query, err := rs.db.Query("SELECT id, name, email, phone, active FROM Venues WHERE id=?", venueID)
    if err != nil {
        log.Fatal(err)
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    for query.Next() {

        err = query.Scan(&venueID, &venue.Name, &venue.Email, &venue.Phone, &venue.Active)
        if err != nil {
            log.Fatal(err)
            http.Error(w, err.Error(), http.StatusInternalServerError)
            return
        }

        data.Venue = venue
    }

    if err := rs.tmpl.ExecuteTemplate(w, "venues-edit", data); err != nil {
        log.Fatal(err)
        http.Error(w, err.Error(), http.StatusInternalServerError)
    }
}


func getVenue(s *sessions.Session) Venue {
    val := s.Values["venue"]
    var venue = Venue{}
    venue, ok := val.(Venue)
    if !ok {
        log.Println("no venue found")
        return Venue{}
    }
    return venue
}

Answer 1

It turns out that I needed to register a struct to use it in Gorilla sessions.

import (
"encoding/gob"
)

func main() {
 gob.Register(Venue{})
}