From f7449396e8f3f21ef17837efc4304ba2195287fc Mon Sep 17 00:00:00 2001
From: Oskar Hahn <mail@oshahn.de>
Date: Sat, 15 Jan 2022 13:43:18 +0100
Subject: [PATCH] Cleanup datastore package (#400)

* Remove fetch api
* Move it to projector, since it is used there
---
 internal/projector/datastore/alias.go         |  9 +++++++
 .../projector}/datastore/fetch.go             | 25 +++++--------------
 .../projector}/datastore/fetch_test.go        |  2 +-
 internal/projector/projector.go               |  2 +-
 internal/projector/projector_test.go          |  2 +-
 internal/projector/slide/agenda.go            |  2 +-
 internal/projector/slide/agenda_test.go       |  2 +-
 internal/projector/slide/assignment.go        |  2 +-
 internal/projector/slide/assignment_test.go   |  2 +-
 internal/projector/slide/list_of_speakers.go  |  2 +-
 .../projector/slide/list_of_speakers_test.go  |  2 +-
 internal/projector/slide/mediafile.go         |  2 +-
 internal/projector/slide/mediafile_test.go    |  2 +-
 internal/projector/slide/meeting.go           |  2 +-
 internal/projector/slide/motion.go            |  2 +-
 internal/projector/slide/motion_block.go      |  2 +-
 internal/projector/slide/motion_block_test.go |  2 +-
 internal/projector/slide/motion_test.go       |  2 +-
 internal/projector/slide/poll.go              |  2 +-
 internal/projector/slide/poll_test.go         |  2 +-
 internal/projector/slide/projector.go         |  2 +-
 internal/projector/slide/projector_test.go    |  2 +-
 internal/projector/slide/topic.go             |  2 +-
 internal/projector/slide/topic_test.go        |  2 +-
 internal/projector/slide/user.go              |  2 +-
 internal/projector/slide/user_test.go         |  2 +-
 internal/projector/slides.go                  |  2 +-
 pkg/datastore/datastore.go                    | 13 ++++++++++
 pkg/datastore/gen_request/value.go.tmpl       | 23 ++++++++---------
 pkg/datastore/interfaces.go                   |  9 -------
 pkg/datastore/request.go                      |  7 ++++++
 pkg/datastore/request_generated.go            | 14 +++++++++++
 32 files changed, 85 insertions(+), 65 deletions(-)
 create mode 100644 internal/projector/datastore/alias.go
 rename {pkg => internal/projector}/datastore/fetch.go (88%)
 rename {pkg => internal/projector}/datastore/fetch_test.go (99%)
 delete mode 100644 pkg/datastore/interfaces.go

diff --git a/internal/projector/datastore/alias.go b/internal/projector/datastore/alias.go
new file mode 100644
index 00000000..256cbe3a
--- /dev/null
+++ b/internal/projector/datastore/alias.go
@@ -0,0 +1,9 @@
+package datastore
+
+import "github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+
+// NewRecorder from datastore.NewRecorder
+var NewRecorder = datastore.NewRecorder
+
+// DoesNotExistError is a type alias from datastore.DoesNotExistError
+type DoesNotExistError = datastore.DoesNotExistError
diff --git a/pkg/datastore/fetch.go b/internal/projector/datastore/fetch.go
similarity index 88%
rename from pkg/datastore/fetch.go
rename to internal/projector/datastore/fetch.go
index 6358e90a..1a064835 100644
--- a/pkg/datastore/fetch.go
+++ b/internal/projector/datastore/fetch.go
@@ -5,14 +5,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"strings"
-)
 
-// Getter can get values from keys.
-//
-// The Datastore object implements this interface.
-type Getter interface {
-	Get(ctx context.Context, keys ...string) (map[string][]byte, error)
-}
+	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+)
 
 // Fetcher is a helper to fetch many keys from the datastore.
 //
@@ -24,12 +19,12 @@ type Getter interface {
 //
 // Make sure to call Fetcher.Err() at the end to see, if an error happend.
 type Fetcher struct {
-	getter Getter
+	getter datastore.Getter
 	err    error
 }
 
 // NewFetcher initializes a Fetcher object.
-func NewFetcher(getter Getter) *Fetcher {
+func NewFetcher(getter datastore.Getter) *Fetcher {
 	return &Fetcher{getter: getter}
 }
 
@@ -85,7 +80,7 @@ func (f *Fetcher) FetchIfExist(ctx context.Context, value interface{}, keyFmt st
 	}
 
 	if fields[idField] == nil {
-		f.err = DoesNotExistError(fqid)
+		f.err = datastore.DoesNotExistError(fqid)
 		return
 	}
 	if fields[fqfield] == nil {
@@ -121,7 +116,7 @@ func (f *Fetcher) Object(ctx context.Context, fqID string, fields ...string) map
 	}
 
 	if vals[fqID+"/id"] == nil {
-		f.err = DoesNotExistError(fqID)
+		f.err = datastore.DoesNotExistError(fqID)
 		return nil
 	}
 
@@ -163,11 +158,3 @@ func String(ctx context.Context, fetch FetchFunc, keyFmt string, a ...interface{
 	fetch(ctx, &value, keyFmt, a...)
 	return value
 }
-
-// DoesNotExistError is thrown by the methods of a Fetcher when an object does
-// not exist.
-type DoesNotExistError string
-
-func (e DoesNotExistError) Error() string {
-	return fmt.Sprintf("%s does not exist.", string(e))
-}
diff --git a/pkg/datastore/fetch_test.go b/internal/projector/datastore/fetch_test.go
similarity index 99%
rename from pkg/datastore/fetch_test.go
rename to internal/projector/datastore/fetch_test.go
index d73ab1a8..4a53a246 100644
--- a/pkg/datastore/fetch_test.go
+++ b/internal/projector/datastore/fetch_test.go
@@ -7,7 +7,7 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
diff --git a/internal/projector/projector.go b/internal/projector/projector.go
index 4c6c051d..d354007b 100644
--- a/internal/projector/projector.go
+++ b/internal/projector/projector.go
@@ -7,7 +7,7 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 // Datastore gets values for keys and informs, if they change.
diff --git a/internal/projector/projector_test.go b/internal/projector/projector_test.go
index 0719dea5..3450e2ff 100644
--- a/internal/projector/projector_test.go
+++ b/internal/projector/projector_test.go
@@ -8,7 +8,7 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
diff --git a/internal/projector/slide/agenda.go b/internal/projector/slide/agenda.go
index 590569b5..05c6989c 100644
--- a/internal/projector/slide/agenda.go
+++ b/internal/projector/slide/agenda.go
@@ -8,7 +8,7 @@ import (
 	"strings"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbAgendaItem struct {
diff --git a/internal/projector/slide/agenda_test.go b/internal/projector/slide/agenda_test.go
index 4c284614..bd39a4ab 100644
--- a/internal/projector/slide/agenda_test.go
+++ b/internal/projector/slide/agenda_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/assignment.go b/internal/projector/slide/assignment.go
index bd6c3df5..f844426f 100644
--- a/internal/projector/slide/assignment.go
+++ b/internal/projector/slide/assignment.go
@@ -7,7 +7,7 @@ import (
 	"sort"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbAssignment struct {
diff --git a/internal/projector/slide/assignment_test.go b/internal/projector/slide/assignment_test.go
index 69f5552c..a6299ddf 100644
--- a/internal/projector/slide/assignment_test.go
+++ b/internal/projector/slide/assignment_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/list_of_speakers.go b/internal/projector/slide/list_of_speakers.go
index c7e3ee80..e2025aa5 100644
--- a/internal/projector/slide/list_of_speakers.go
+++ b/internal/projector/slide/list_of_speakers.go
@@ -9,7 +9,7 @@ import (
 	"strings"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbListOfSpeakers struct {
diff --git a/internal/projector/slide/list_of_speakers_test.go b/internal/projector/slide/list_of_speakers_test.go
index e7ef2817..1f83e642 100644
--- a/internal/projector/slide/list_of_speakers_test.go
+++ b/internal/projector/slide/list_of_speakers_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
diff --git a/internal/projector/slide/mediafile.go b/internal/projector/slide/mediafile.go
index 7d19e240..c85c9889 100644
--- a/internal/projector/slide/mediafile.go
+++ b/internal/projector/slide/mediafile.go
@@ -6,7 +6,7 @@ import (
 	"fmt"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbMediafile struct {
diff --git a/internal/projector/slide/mediafile_test.go b/internal/projector/slide/mediafile_test.go
index 4679c0c4..a9ca6353 100644
--- a/internal/projector/slide/mediafile_test.go
+++ b/internal/projector/slide/mediafile_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/meeting.go b/internal/projector/slide/meeting.go
index ef5256f6..c3b0dcba 100644
--- a/internal/projector/slide/meeting.go
+++ b/internal/projector/slide/meeting.go
@@ -5,7 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbMeeting struct {
diff --git a/internal/projector/slide/motion.go b/internal/projector/slide/motion.go
index 29d9b305..32ccb715 100644
--- a/internal/projector/slide/motion.go
+++ b/internal/projector/slide/motion.go
@@ -8,7 +8,7 @@ import (
 	"strings"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbMotionState struct {
diff --git a/internal/projector/slide/motion_block.go b/internal/projector/slide/motion_block.go
index 78100f74..235af9ef 100644
--- a/internal/projector/slide/motion_block.go
+++ b/internal/projector/slide/motion_block.go
@@ -6,7 +6,7 @@ import (
 	"fmt"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbMotionBlock struct {
diff --git a/internal/projector/slide/motion_block_test.go b/internal/projector/slide/motion_block_test.go
index d4cb6d51..fdde1566 100644
--- a/internal/projector/slide/motion_block_test.go
+++ b/internal/projector/slide/motion_block_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/motion_test.go b/internal/projector/slide/motion_test.go
index 89f3583b..0208ef75 100644
--- a/internal/projector/slide/motion_test.go
+++ b/internal/projector/slide/motion_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/poll.go b/internal/projector/slide/poll.go
index 189a4f37..8904073e 100644
--- a/internal/projector/slide/poll.go
+++ b/internal/projector/slide/poll.go
@@ -8,7 +8,7 @@ import (
 	"strings"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type optionRepr struct {
diff --git a/internal/projector/slide/poll_test.go b/internal/projector/slide/poll_test.go
index 936df00c..7418ca2a 100644
--- a/internal/projector/slide/poll_test.go
+++ b/internal/projector/slide/poll_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/projector.go b/internal/projector/slide/projector.go
index f6e4073b..e34150b8 100644
--- a/internal/projector/slide/projector.go
+++ b/internal/projector/slide/projector.go
@@ -6,7 +6,7 @@ import (
 	"fmt"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbProjectorCountdown struct {
diff --git a/internal/projector/slide/projector_test.go b/internal/projector/slide/projector_test.go
index 4f504055..95772699 100644
--- a/internal/projector/slide/projector_test.go
+++ b/internal/projector/slide/projector_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/topic.go b/internal/projector/slide/topic.go
index 620fa588..51ab5bee 100644
--- a/internal/projector/slide/topic.go
+++ b/internal/projector/slide/topic.go
@@ -6,7 +6,7 @@ import (
 	"fmt"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 type dbTopic struct {
diff --git a/internal/projector/slide/topic_test.go b/internal/projector/slide/topic_test.go
index 34ddebfc..13948d03 100644
--- a/internal/projector/slide/topic_test.go
+++ b/internal/projector/slide/topic_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slide/user.go b/internal/projector/slide/user.go
index ed17ac14..90407cee 100644
--- a/internal/projector/slide/user.go
+++ b/internal/projector/slide/user.go
@@ -8,7 +8,7 @@ import (
 	"strings"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 // DbUser is the class with methods to get needed User Informations
diff --git a/internal/projector/slide/user_test.go b/internal/projector/slide/user_test.go
index a4fa443c..008b586e 100644
--- a/internal/projector/slide/user_test.go
+++ b/internal/projector/slide/user_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/slide"
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
 	"github.com/OpenSlides/openslides-autoupdate-service/pkg/dsmock"
 	"github.com/stretchr/testify/assert"
 )
diff --git a/internal/projector/slides.go b/internal/projector/slides.go
index dd4343fb..ede0ef63 100644
--- a/internal/projector/slides.go
+++ b/internal/projector/slides.go
@@ -5,7 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 
-	"github.com/OpenSlides/openslides-autoupdate-service/pkg/datastore"
+	"github.com/OpenSlides/openslides-autoupdate-service/internal/projector/datastore"
 )
 
 // Slider knows how to create a slide.
diff --git a/pkg/datastore/datastore.go b/pkg/datastore/datastore.go
index a27da333..f40b2a0f 100644
--- a/pkg/datastore/datastore.go
+++ b/pkg/datastore/datastore.go
@@ -27,6 +27,19 @@ const (
 	httpTimeout              = 3 * time.Second
 )
 
+// Updater returns keys that have changes. Blocks until there is
+// changed data.
+type Updater interface {
+	Update(context.Context) (map[string][]byte, error)
+}
+
+// Getter can get values from keys.
+//
+// The Datastore object implements this interface.
+type Getter interface {
+	Get(ctx context.Context, keys ...string) (map[string][]byte, error)
+}
+
 // Datastore can be used to get values from the datastore-service.
 //
 // Has to be created with datastore.New().
diff --git a/pkg/datastore/gen_request/value.go.tmpl b/pkg/datastore/gen_request/value.go.tmpl
index c654ef20..fb5b5236 100644
--- a/pkg/datastore/gen_request/value.go.tmpl
+++ b/pkg/datastore/gen_request/value.go.tmpl
@@ -37,14 +37,13 @@ type {{.TypeName}} struct {
 	}
 {{end}}
 
-{{if not .MaybeType}}
-	// Lazy sets a value as soon as it es executed.
-	//
-	// Make sure to call request.Execute() before using the value.
-	func (v *{{.TypeName}}) Lazy(value *{{.GoType}}) {
-		v.lazies = append(v.lazies, value)
-	}
-{{end}}
+
+// Lazy sets a value as soon as it es executed.
+//
+// Make sure to call request.Execute() before using the value.
+func (v *{{.TypeName}}) Lazy(value *{{.GoType}}) {
+	v.lazies = append(v.lazies, value)
+}
 
 {{if not .MaybeType}}
 	// ErrorLater is like Value but does not return an error.
@@ -67,10 +66,10 @@ type {{.TypeName}} struct {
 		return v.value
 	}
 {{else}}
-// ErrorLater is like Value but does not return an error.
-//
-// If an error happs, it is saved internaly. Make sure to call request.Err() later to
-// access it.
+	// ErrorLater is like Value but does not return an error.
+	//
+	// If an error happs, it is saved internaly. Make sure to call request.Err() later to
+	// access it.
 	func (v *{{.TypeName}}) ErrorLater(ctx context.Context) ({{.GoType}}, bool) {
 		if v.request.err != nil {
 			return {{.Zero}}, false
diff --git a/pkg/datastore/interfaces.go b/pkg/datastore/interfaces.go
deleted file mode 100644
index d4fa04ad..00000000
--- a/pkg/datastore/interfaces.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package datastore
-
-import "context"
-
-// Updater returns keys that have changes. Blocks until there is
-// changed data.
-type Updater interface {
-	Update(context.Context) (map[string][]byte, error)
-}
diff --git a/pkg/datastore/request.go b/pkg/datastore/request.go
index b7350546..22136ee7 100644
--- a/pkg/datastore/request.go
+++ b/pkg/datastore/request.go
@@ -153,3 +153,10 @@ func (v *ValueRequiredInt) execute(p []byte) error {
 	v.executed = true
 	return nil
 }
+
+// DoesNotExistError is thrown when an object does not exist.
+type DoesNotExistError string
+
+func (e DoesNotExistError) Error() string {
+	return fmt.Sprintf("%s does not exist.", string(e))
+}
diff --git a/pkg/datastore/request_generated.go b/pkg/datastore/request_generated.go
index e6888d76..cdeb4b73 100644
--- a/pkg/datastore/request_generated.go
+++ b/pkg/datastore/request_generated.go
@@ -455,6 +455,13 @@ func (v *ValueMaybeInt) Value(ctx context.Context) (int, bool, error) {
 	return v.value, !v.isNull, nil
 }
 
+// Lazy sets a value as soon as it es executed.
+//
+// Make sure to call request.Execute() before using the value.
+func (v *ValueMaybeInt) Lazy(value *int) {
+	v.lazies = append(v.lazies, value)
+}
+
 // ErrorLater is like Value but does not return an error.
 //
 // If an error happs, it is saved internaly. Make sure to call request.Err() later to
@@ -517,6 +524,13 @@ func (v *ValueMaybeString) Value(ctx context.Context) (string, bool, error) {
 	return v.value, !v.isNull, nil
 }
 
+// Lazy sets a value as soon as it es executed.
+//
+// Make sure to call request.Execute() before using the value.
+func (v *ValueMaybeString) Lazy(value *string) {
+	v.lazies = append(v.lazies, value)
+}
+
 // ErrorLater is like Value but does not return an error.
 //
 // If an error happs, it is saved internaly. Make sure to call request.Err() later to