GetMutiでentityがなかった場合

getmultierr.go

package getmultitest

import (
	"appengine"
	"appengine/datastore"
	"fmt"
	"net/http"
)

func init() {
	http.HandleFunc("/", handler)
}

type Test struct {
	Value string
}

func handler(w http.ResponseWriter, r *http.Request) {
	c := appengine.NewContext(r)
	key1 := datastore.NewKey(c, "Test", "1", 0, nil)
	key2 := datastore.NewKey(c, "Test", "2", 0, nil)
	key3 := datastore.NewKey(c, "Test", "3", 0, nil)

	if _, err := datastore.Put(c, key1, &Test{"test1"}); err != nil {
		http.Error(w, err.Error(), 500)
		return
	}
	if _, err := datastore.Put(c, key3, &Test{"test3"}); err != nil {
		http.Error(w, err.Error(), 500)
		return
	}

	keys := []*datastore.Key{key1, key2, key3}
	values := make([]Test, 3)
	if err := datastore.GetMulti(c, keys, values); err != nil {
		if merr, ok := err.(appengine.MultiError); ok {
			fmt.Fprintf(w, "%v¥n", keys)
			fmt.Fprintf(w, "%v¥n", values)
			fmt.Fprintf(w, "%#v¥n", merr)
		}
	}
}

結果

[/Test,1 /Test,2 /Test,3]
[{test1} {} {test3}]
appengine.MultiError{error(nil), (*errors.errorString)(0xc21000abe0), error(nil)}

MultiErrorに入ってるErrNoSuchEntityをチェックしてやらないといけなくてちょー面倒(´･ω･`)