Fix minor bug in ParseIndexColumn

service/datastore/index.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 (
         "bytes"
         "fmt"
         "strings"
 )
 
 // IndexColumn represents a sort order for a single entity field.
 type IndexColumn struct {
         Property   string
         Descending bool
 }
 
 // ParseIndexColumn takes a spec in the form of /\s*-?\s*.+\s*/, and
 // returns an IndexColumn. Examples are:
 //   `- Field `:  IndexColumn{Property: "Field", Descending: true}
 //   `Something`: IndexColumn{Property: "Something", Descending: false}
 //
 // `+Field` is invalid. `` is invalid.
 func ParseIndexColumn(spec string) (IndexColumn, error) {
         col := IndexColumn{}
+        spec = strings.TrimSpace(spec)
         if strings.HasPrefix(spec, "-") {
                 col.Descending = true
                 col.Property = strings.TrimSpace(spec[1:])
         } else if strings.HasPrefix(spec, "+") {
                 return col, fmt.Errorf("datastore: invalid order: %q", spec)
         } else {
                 col.Property = strings.TrimSpace(spec)
         }
         if col.Property == "" {
-                return col, fmt.Errorf("datastore: empty order")
+                return col, fmt.Errorf("datastore: empty order: %q", spec)
         }
         return col, nil
 }
 
 func (i IndexColumn) cmp(o IndexColumn) int {
         // sort ascending first
         if !i.Descending && o.Descending {
                 return -1
         } else if i.Descending && !o.Descending {
                 return 1
@@ skipping 208 matching lines @@
         }
         for _, sb := range id.SortBy {
                 wr('/')
                 if sb.Descending {
                         wr('-')
                 }
                 ws(sb.Property)
         }
         return ret.String()
 }