Fix miscellaneous prod bugs.

service/datastore/multiarg.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package datastore
 
 import (
         "fmt"
         "reflect"
 
@@ skipping 218 matching lines @@
 
 func newKeyObjErr(nk newKeyFunc, src interface{}) (Key, error) {
         pls, name := mkPLSName(src)
         if key, _ := pls.GetMetaDefault("key", nil).(Key); key != nil {
                 return key, nil
         }
 
         // get kind
         kind := pls.GetMetaDefault("kind", name).(string)
         if kind == "" {
                 return nil, fmt.Errorf("unable to extract $kind from %v", src)

[dnj (Google), 2015/08/15 02:32:32]

(this error)

         }
 
         // get id - allow both to be default for default keys
         sid := pls.GetMetaDefault("id", "").(string)
         iid := pls.GetMetaDefault("id", 0).(int64)
 
         // get parent
         par, _ := pls.GetMetaDefault("parent", nil).(Key)
 
         return nk(kind, sid, iid, par), nil
@@ skipping 10 matching lines @@
                 pls.SetMeta("kind", key.Kind())
                 pls.SetMeta("parent", key.Parent())
         }
 }
 
 func mkPLSName(o interface{}) (PropertyLoadSaver, string) {
         if pls, ok := o.(*structPLS); ok {
                 return pls, pls.o.Type().Name()
         }
         if pls, ok := o.(PropertyLoadSaver); ok {
-                return pls, ""
+                v, _ := getPLSValue(o)
+                return pls, v.Type().Name()

[iannucci, 2015/08/15 02:23:53]

This looks really wrong to me. We already see if it's a *structPLS above. This
is for implementors of just the PropertyLoadSaver interface (e.g. PropertyMap),
which won't have .Type()

[dnj (Google), 2015/08/15 02:32:32]

The problem occurs when I implement a custom PropertyLoadSaver. That
PropertyLoadSaver doesn't set the $kind meta, so newKeyObjErr gets back "" for
the name. It then runs GetMetaDefault("kind", ""), and since my PLS doesn't
declare/export $kind, the name is "" and I hit the ensuing error.

         }
         pls := GetPLS(o)
         name := pls.(*structPLS).o.Type().Name()
         return pls, name
 }