最初在Python中创建数据存储时，如何在Go中使用数据存储区GAE？

Question

I have a datastore kind "Items" which was created in Python, in this code do not iterate data q.Run() in Go (it's version 2):

type Items struct{
    code string
    date time.Time
    name string
}
func getcode(w http.ResponseWriter, r *http.Request) {
    code := mux.Vars(r)["code"]
    fmt.Fprintf(w,"get code %v",code)

    c := appengine.NewContext(r)
    q := datastore.NewQuery("Items")

    for t := q.Run(c); ; {
        var x Items
        key, err := t.Next(&x)
        fmt.Fprintf(w,"%v",key)

        if err == datastore.Done {
            break
        }
        if err != nil {
            //serveError(c, w, err)
            return
        }
        fmt.Fprintf(w, "Code=%v
", x.code)
    }

Answer 1

The Datastore package uses reflection to fill struct fields when reading an entity from the datastore. In Go struct fields whose name start with lowercase letter are not exported. Unexported fields cannot be set from packages other than the one they were defined in.

Only exported fields (that start with uppercase letters) can be stored in / retrieved from the datastore. You can use tags to tell what the name of the property is in the datastore in case it differs from the field's name. So you have to change your Items struct to this:

type Items struct {
    Code string    `datastore:"code"`
    Date time.Time `datastore:"date"`
    Name string    `datastore:"name"`
}