// [START func_root]
func root(w http.ResponseWriter, r *http.Request) {
c := appengine.NewContext(r)
// Ancestor queries, as shown here, are strongly consistent with the High
// Replication Datastore. Queries that span entity groups are eventually
// consistent. If we omitted the .Ancestor from this query there would be
// a slight chance that Greeting that had just been written would not
// show up in a query.
// [START query]
q := datastore.NewQuery("Greeting").Ancestor(mdl.GuestbookKey(c)).Order("-Date").Limit(10)
// [END query]
// [START getall]
greetings := make([]mdl.Greeting, 0, 10)
if _, err := q.GetAll(c, &greetings); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
// [END getall]
if err := guestbookTemplate.Execute(w, greetings); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
// [START func_sign]
func Sign(w http.ResponseWriter, r *http.Request) {
c := appengine.NewContext(r)
g := mdl.Greeting{
Content: r.FormValue("content"),
Date: time.Now(),
}
if u := user.Current(c); u != nil {
g.Author = u.String()
}
// We set the same parent key on every Greeting entity to ensure each Greeting
// is in the same entity group. Queries across the single entity group
// will be consistent. However, the write rate to a single entity group
// should be limited to ~1/second.
key := datastore.NewIncompleteKey(c, "Greeting", mdl.GuestbookKey(c))
_, err := datastore.Put(c, key, &g)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
http.Redirect(w, r, "/", http.StatusFound)
}