chore: make connection paging more like standard

app/msgbus/service.go

@@ -476,8 +476,8 @@ func (e *PostEvent) Values() any {
 	}
 
 	return struct {
-		Payload []byte
+		Payload []byte   `json:"payload"`
-		Tags    []string
+		Tags    []string `json:"tags,omitempty"`
 	}{
 		Payload: e.payload,
 		Tags:    e.tags,

internal/graph/generated/generated.go

@@ -59,9 +59,12 @@ type ComplexityRoot struct {
 
 	Event struct {
 		Bytes   func(childComplexity int) int
+		Created func(childComplexity int) int
 		EventID func(childComplexity int) int
 		ID      func(childComplexity int) int
+		Linked  func(childComplexity int) int
 		Meta    func(childComplexity int) int
+		Type    func(childComplexity int) int
 		Values  func(childComplexity int) int
 	}
 
@@ -163,6 +166,13 @@ func (e *executableSchema) Complexity(typeName, field string, childComplexity in
 
 		return e.complexity.Event.Bytes(childComplexity), true
 
+	case "Event.created":
+		if e.complexity.Event.Created == nil {
+			break
+		}
+
+		return e.complexity.Event.Created(childComplexity), true
+
 	case "Event.eventID":
 		if e.complexity.Event.EventID == nil {
 			break
@@ -177,6 +187,13 @@ func (e *executableSchema) Complexity(typeName, field string, childComplexity in
 
 		return e.complexity.Event.ID(childComplexity), true
 
+	case "Event.linked":
+		if e.complexity.Event.Linked == nil {
+			break
+		}
+
+		return e.complexity.Event.Linked(childComplexity), true
+
 	case "Event.meta":
 		if e.complexity.Event.Meta == nil {
 			break
@@ -184,6 +201,13 @@ func (e *executableSchema) Complexity(typeName, field string, childComplexity in
 
 		return e.complexity.Event.Meta(childComplexity), true
 
+	case "Event.type":
+		if e.complexity.Event.Type == nil {
+			break
+		}
+
+		return e.complexity.Event.Type(childComplexity), true
+
 	case "Event.values":
 		if e.complexity.Event.Values == nil {
 			break
@@ -497,7 +521,11 @@ type Event implements Edge @goModel(model: "github.com/sour-is/ev/pkg/es.GQLEven
     eventID: String!
     values: Map!
     bytes: String!
+    type: String!
+    created: Time!
     meta: Meta!
+
+    linked: Event
 }`, BuiltIn: false},
 	{Name: "../../../pkg/gql/common.graphqls", Input: `scalar Time
 scalar Map
@@ -507,7 +535,8 @@ type Connection @goModel(model: "github.com/sour-is/ev/pkg/gql.Connection") {
     edges: [Edge!]!
 }
 input PageInput  @goModel(model: "github.com/sour-is/ev/pkg/gql.PageInput") {
-    idx: Int = 0
+    after:  Int = 0
+    before: Int
     count:  Int = 30
 }
 type PageInfo  @goModel(model: "github.com/sour-is/ev/pkg/gql.PageInfo") {
@@ -1053,6 +1082,94 @@ func (ec *executionContext) fieldContext_Event_bytes(ctx context.Context, field
 	return fc, nil
 }
 
+func (ec *executionContext) _Event_type(ctx context.Context, field graphql.CollectedField, obj *es.GQLEvent) (ret graphql.Marshaler) {
+	fc, err := ec.fieldContext_Event_type(ctx, field)
+	if err != nil {
+		return graphql.Null
+	}
+	ctx = graphql.WithFieldContext(ctx, fc)
+	defer func() {
+		if r := recover(); r != nil {
+			ec.Error(ctx, ec.Recover(ctx, r))
+			ret = graphql.Null
+		}
+	}()
+	resTmp, err := ec.ResolverMiddleware(ctx, func(rctx context.Context) (interface{}, error) {
+		ctx = rctx // use context from middleware stack in children
+		return obj.Type(), nil
+	})
+	if err != nil {
+		ec.Error(ctx, err)
+		return graphql.Null
+	}
+	if resTmp == nil {
+		if !graphql.HasFieldError(ctx, fc) {
+			ec.Errorf(ctx, "must not be null")
+		}
+		return graphql.Null
+	}
+	res := resTmp.(string)
+	fc.Result = res
+	return ec.marshalNString2string(ctx, field.Selections, res)
+}
+
+func (ec *executionContext) fieldContext_Event_type(ctx context.Context, field graphql.CollectedField) (fc *graphql.FieldContext, err error) {
+	fc = &graphql.FieldContext{
+		Object:     "Event",
+		Field:      field,
+		IsMethod:   true,
+		IsResolver: false,
+		Child: func(ctx context.Context, field graphql.CollectedField) (*graphql.FieldContext, error) {
+			return nil, errors.New("field of type String does not have child fields")
+		},
+	}
+	return fc, nil
+}
+
+func (ec *executionContext) _Event_created(ctx context.Context, field graphql.CollectedField, obj *es.GQLEvent) (ret graphql.Marshaler) {
+	fc, err := ec.fieldContext_Event_created(ctx, field)
+	if err != nil {
+		return graphql.Null
+	}
+	ctx = graphql.WithFieldContext(ctx, fc)
+	defer func() {
+		if r := recover(); r != nil {
+			ec.Error(ctx, ec.Recover(ctx, r))
+			ret = graphql.Null
+		}
+	}()
+	resTmp, err := ec.ResolverMiddleware(ctx, func(rctx context.Context) (interface{}, error) {
+		ctx = rctx // use context from middleware stack in children
+		return obj.Created(), nil
+	})
+	if err != nil {
+		ec.Error(ctx, err)
+		return graphql.Null
+	}
+	if resTmp == nil {
+		if !graphql.HasFieldError(ctx, fc) {
+			ec.Errorf(ctx, "must not be null")
+		}
+		return graphql.Null
+	}
+	res := resTmp.(time.Time)
+	fc.Result = res
+	return ec.marshalNTime2timeᚐTime(ctx, field.Selections, res)
+}
+
+func (ec *executionContext) fieldContext_Event_created(ctx context.Context, field graphql.CollectedField) (fc *graphql.FieldContext, err error) {
+	fc = &graphql.FieldContext{
+		Object:     "Event",
+		Field:      field,
+		IsMethod:   true,
+		IsResolver: false,
+		Child: func(ctx context.Context, field graphql.CollectedField) (*graphql.FieldContext, error) {
+			return nil, errors.New("field of type Time does not have child fields")
+		},
+	}
+	return fc, nil
+}
+
 func (ec *executionContext) _Event_meta(ctx context.Context, field graphql.CollectedField, obj *es.GQLEvent) (ret graphql.Marshaler) {
 	fc, err := ec.fieldContext_Event_meta(ctx, field)
 	if err != nil {
@@ -1107,6 +1224,65 @@ func (ec *executionContext) fieldContext_Event_meta(ctx context.Context, field g
 	return fc, nil
 }
 
+func (ec *executionContext) _Event_linked(ctx context.Context, field graphql.CollectedField, obj *es.GQLEvent) (ret graphql.Marshaler) {
+	fc, err := ec.fieldContext_Event_linked(ctx, field)
+	if err != nil {
+		return graphql.Null
+	}
+	ctx = graphql.WithFieldContext(ctx, fc)
+	defer func() {
+		if r := recover(); r != nil {
+			ec.Error(ctx, ec.Recover(ctx, r))
+			ret = graphql.Null
+		}
+	}()
+	resTmp, err := ec.ResolverMiddleware(ctx, func(rctx context.Context) (interface{}, error) {
+		ctx = rctx // use context from middleware stack in children
+		return obj.Linked(ctx)
+	})
+	if err != nil {
+		ec.Error(ctx, err)
+		return graphql.Null
+	}
+	if resTmp == nil {
+		return graphql.Null
+	}
+	res := resTmp.(*es.GQLEvent)
+	fc.Result = res
+	return ec.marshalOEvent2ᚖgithubᚗcomᚋsourᚑisᚋevᚋpkgᚋesᚐGQLEvent(ctx, field.Selections, res)
+}
+
+func (ec *executionContext) fieldContext_Event_linked(ctx context.Context, field graphql.CollectedField) (fc *graphql.FieldContext, err error) {
+	fc = &graphql.FieldContext{
+		Object:     "Event",
+		Field:      field,
+		IsMethod:   true,
+		IsResolver: false,
+		Child: func(ctx context.Context, field graphql.CollectedField) (*graphql.FieldContext, error) {
+			switch field.Name {
+			case "id":
+				return ec.fieldContext_Event_id(ctx, field)
+			case "eventID":
+				return ec.fieldContext_Event_eventID(ctx, field)
+			case "values":
+				return ec.fieldContext_Event_values(ctx, field)
+			case "bytes":
+				return ec.fieldContext_Event_bytes(ctx, field)
+			case "type":
+				return ec.fieldContext_Event_type(ctx, field)
+			case "created":
+				return ec.fieldContext_Event_created(ctx, field)
+			case "meta":
+				return ec.fieldContext_Event_meta(ctx, field)
+			case "linked":
+				return ec.fieldContext_Event_linked(ctx, field)
+			}
+			return nil, fmt.Errorf("no field named %q was found under type Event", field.Name)
+		},
+	}
+	return fc, nil
+}
+
 func (ec *executionContext) _Meta_eventID(ctx context.Context, field graphql.CollectedField, obj *event.Meta) (ret graphql.Marshaler) {
 	fc, err := ec.fieldContext_Meta_eventID(ctx, field)
 	if err != nil {
@@ -2298,8 +2474,14 @@ func (ec *executionContext) fieldContext_Subscription_eventAdded(ctx context.Con
 				return ec.fieldContext_Event_values(ctx, field)
 			case "bytes":
 				return ec.fieldContext_Event_bytes(ctx, field)
+			case "type":
+				return ec.fieldContext_Event_type(ctx, field)
+			case "created":
+				return ec.fieldContext_Event_created(ctx, field)
 			case "meta":
 				return ec.fieldContext_Event_meta(ctx, field)
+			case "linked":
+				return ec.fieldContext_Event_linked(ctx, field)
 			}
 			return nil, fmt.Errorf("no field named %q was found under type Event", field.Name)
 		},
@@ -4217,25 +4399,33 @@ func (ec *executionContext) unmarshalInputPageInput(ctx context.Context, obj int
 		asMap[k] = v
 	}
 
-	if _, present := asMap["idx"]; !present {
+	if _, present := asMap["after"]; !present {
-		asMap["idx"] = 0
+		asMap["after"] = 0
 	}
 	if _, present := asMap["count"]; !present {
 		asMap["count"] = 30
 	}
 
-	fieldsInOrder := [...]string{"idx", "count"}
+	fieldsInOrder := [...]string{"after", "before", "count"}
 	for _, k := range fieldsInOrder {
 		v, ok := asMap[k]
 		if !ok {
 			continue
 		}
 		switch k {
-		case "idx":
+		case "after":
 			var err error
 
-			ctx := graphql.WithPathContext(ctx, graphql.NewPathWithField("idx"))
+			ctx := graphql.WithPathContext(ctx, graphql.NewPathWithField("after"))
-			it.Idx, err = ec.unmarshalOInt2ᚖint64(ctx, v)
+			it.After, err = ec.unmarshalOInt2ᚖint64(ctx, v)
+			if err != nil {
+				return it, err
+			}
+		case "before":
+			var err error
+
+			ctx := graphql.WithPathContext(ctx, graphql.NewPathWithField("before"))
+			it.Before, err = ec.unmarshalOInt2ᚖint64(ctx, v)
 			if err != nil {
 				return it, err
 			}
@@ -4330,36 +4520,67 @@ func (ec *executionContext) _Event(ctx context.Context, sel ast.SelectionSet, ob
 			out.Values[i] = ec._Event_id(ctx, field, obj)
 
 			if out.Values[i] == graphql.Null {
-				invalids++
+				atomic.AddUint32(&invalids, 1)
 			}
 		case "eventID":
 
 			out.Values[i] = ec._Event_eventID(ctx, field, obj)
 
 			if out.Values[i] == graphql.Null {
-				invalids++
+				atomic.AddUint32(&invalids, 1)
 			}
 		case "values":
 
 			out.Values[i] = ec._Event_values(ctx, field, obj)
 
 			if out.Values[i] == graphql.Null {
-				invalids++
+				atomic.AddUint32(&invalids, 1)
 			}
 		case "bytes":
 
 			out.Values[i] = ec._Event_bytes(ctx, field, obj)
 
 			if out.Values[i] == graphql.Null {
-				invalids++
+				atomic.AddUint32(&invalids, 1)
+			}
+		case "type":
+
+			out.Values[i] = ec._Event_type(ctx, field, obj)
+
+			if out.Values[i] == graphql.Null {
+				atomic.AddUint32(&invalids, 1)
+			}
+		case "created":
+
+			out.Values[i] = ec._Event_created(ctx, field, obj)
+
+			if out.Values[i] == graphql.Null {
+				atomic.AddUint32(&invalids, 1)
 			}
 		case "meta":
 
 			out.Values[i] = ec._Event_meta(ctx, field, obj)
 
 			if out.Values[i] == graphql.Null {
-				invalids++
+				atomic.AddUint32(&invalids, 1)
 			}
+		case "linked":
+			field := field
+
+			innerFunc := func(ctx context.Context) (res graphql.Marshaler) {
+				defer func() {
+					if r := recover(); r != nil {
+						ec.Error(ctx, ec.Recover(ctx, r))
+					}
+				}()
+				res = ec._Event_linked(ctx, field, obj)
+				return res
+			}
+
+			out.Concurrently(i, func() graphql.Marshaler {
+				return innerFunc(ctx)
+
+			})
 		default:
 			panic("unknown field " + strconv.Quote(field.Name))
 		}

pkg/es/driver/disk-store/disk-store.go

@@ -4,6 +4,7 @@ package diskstore
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -208,7 +209,7 @@ func (e *eventLog) Append(ctx context.Context, events event.Events, version uint
 
 	return count, err
 }
-func (e *eventLog) Read(ctx context.Context, pos, count int64) (event.Events, error) {
+func (e *eventLog) Read(ctx context.Context, after, count int64) (event.Events, error) {
 	_, span := lg.Span(ctx)
 	defer span.End()
 
@@ -233,7 +234,7 @@ func (e *eventLog) Read(ctx context.Context, pos, count int64) (event.Events, er
 			return nil
 		}
 
-		start, count := math.PagerBox(first, last, pos, count)
+		start, count := math.PagerBox(first, last, after, count)
 		if count == 0 {
 			return nil
 		}
@@ -246,6 +247,10 @@ func (e *eventLog) Read(ctx context.Context, pos, count int64) (event.Events, er
 			var b []byte
 			b, err = stream.Read(start)
 			if err != nil {
+				if errors.Is(err, wal.ErrNotFound) || errors.Is(err, wal.ErrOutOfRange) {
+					err = fmt.Errorf("%w: empty", es.ErrNotFound)
+				}
+
 				span.RecordError(err)
 				return err
 			}

pkg/es/driver/driver.go

@@ -13,7 +13,7 @@ type Driver interface {
 }
 
 type EventLog interface {
-	Read(ctx context.Context, pos, count int64) (event.Events, error)
+	Read(ctx context.Context, after, count int64) (event.Events, error)
 	Append(ctx context.Context, events event.Events, version uint64) (uint64, error)
 	FirstIndex(context.Context) (uint64, error)
 	LastIndex(context.Context) (uint64, error)

pkg/es/driver/mem-store/mem-store.go

@@ -112,7 +112,7 @@ func (m *eventLog) Append(ctx context.Context, events event.Events, version uint
 }
 
 // Read implements driver.EventStore
-func (m *eventLog) Read(ctx context.Context, pos int64, count int64) (event.Events, error) {
+func (m *eventLog) Read(ctx context.Context, after int64, count int64) (event.Events, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
 
@@ -131,11 +131,11 @@ func (m *eventLog) Read(ctx context.Context, pos int64, count int64) (event.Even
 			return nil
 		}
 
-		start, count := math.PagerBox(first, last, pos, count)
+		start, count := math.PagerBox(first, last, after, count)
 		if count == 0 {
 			return nil
 		}
-		span.AddEvent(fmt.Sprint("box", first, last, pos, count))
+		span.AddEvent(fmt.Sprint("box", first, last, after, count))
 		events = make([]event.Event, math.Abs(count))
 		for i := range events {
 			span.AddEvent(fmt.Sprintf("read event %d of %d", i, math.Abs(count)))

pkg/es/driver/projecter/projecter.go

@@ -47,11 +47,11 @@ type wrapper struct {
 
 var _ driver.EventLog = (*wrapper)(nil)
 
-func (w *wrapper) Read(ctx context.Context, pos int64, count int64) (event.Events, error) {
+func (w *wrapper) Read(ctx context.Context, after int64, count int64) (event.Events, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
 
-	return w.up.Read(ctx, pos, count)
+	return w.up.Read(ctx, after, count)
 }
 func (w *wrapper) Append(ctx context.Context, events event.Events, version uint64) (uint64, error) {
 	ctx, span := lg.Span(ctx)

pkg/es/driver/streamer/streamer.go

@@ -142,11 +142,11 @@ type wrapper struct {
 
 var _ driver.EventLog = (*wrapper)(nil)
 
-func (w *wrapper) Read(ctx context.Context, pos int64, count int64) (event.Events, error) {
+func (w *wrapper) Read(ctx context.Context, after int64, count int64) (event.Events, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
 
-	return w.up.Read(ctx, pos, count)
+	return w.up.Read(ctx, after, count)
 }
 func (w *wrapper) Append(ctx context.Context, events event.Events, version uint64) (uint64, error) {
 	ctx, span := lg.Span(ctx)

pkg/es/es.go

@@ -121,7 +121,6 @@ func (es *EventStore) Save(ctx context.Context, agg event.Aggregate) (uint64, er
 		return 0, nil
 	}
 
-	Mes_save.Add(ctx, 1)
 	span.SetAttributes(
 		attribute.String("agg.type", event.TypeOf(agg)),
 		attribute.String("agg.streamID", agg.StreamID()),
@@ -137,6 +136,7 @@ func (es *EventStore) Save(ctx context.Context, agg event.Aggregate) (uint64, er
 	if err != nil {
 		return 0, err
 	}
+	Mes_save.Add(ctx, int64(count))
 
 	agg.Commit()
 	return count, err
@@ -145,8 +145,6 @@ func (es *EventStore) Load(ctx context.Context, agg event.Aggregate) error {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
 
-	Mes_load.Add(ctx, 1)
-
 	span.SetAttributes(
 		attribute.String("agg.type", event.TypeOf(agg)),
 		attribute.String("agg.streamID", agg.StreamID()),
@@ -162,6 +160,7 @@ func (es *EventStore) Load(ctx context.Context, agg event.Aggregate) error {
 		return err
 	}
 
+	Mes_load.Add(ctx, events.Count())
 	event.Append(agg, events...)
 
 	span.SetAttributes(
@@ -170,20 +169,25 @@ func (es *EventStore) Load(ctx context.Context, agg event.Aggregate) error {
 
 	return nil
 }
-func (es *EventStore) Read(ctx context.Context, streamID string, pos, count int64) (event.Events, error) {
+func (es *EventStore) Read(ctx context.Context, streamID string, after, count int64) (event.Events, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
 
-	Mes_read.Add(ctx, 1)
 	span.SetAttributes(
-		attribute.String("ev.streamID", streamID),
+		attribute.String("streamID", streamID),
+		attribute.Int64("after", after),
+		attribute.Int64("count", count),
 	)
 
 	l, err := es.Driver.EventLog(ctx, streamID)
 	if err != nil {
 		return nil, err
 	}
-	return l.Read(ctx, pos, count)
+
+	events, err := l.Read(ctx, after, count)
+	Mes_read.Add(ctx, events.Count())
+
+	return events, err
 }
 func (es *EventStore) Append(ctx context.Context, streamID string, events event.Events) (uint64, error) {
 	ctx, span := lg.Span(ctx)
@@ -203,6 +207,9 @@ func (es *EventStore) Append(ctx context.Context, streamID string, events event.
 func (es *EventStore) FirstIndex(ctx context.Context, streamID string) (uint64, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
+	span.SetAttributes(
+		attribute.String("ev.streamID", streamID),
+	)
 
 	l, err := es.Driver.EventLog(ctx, streamID)
 	if err != nil {
@@ -213,6 +220,9 @@ func (es *EventStore) FirstIndex(ctx context.Context, streamID string) (uint64,
 func (es *EventStore) LastIndex(ctx context.Context, streamID string) (uint64, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
+	span.SetAttributes(
+		attribute.String("ev.streamID", streamID),
+	)
 
 	l, err := es.Driver.EventLog(ctx, streamID)
 	if err != nil {
@@ -248,6 +258,7 @@ var ErrNoDriver = errors.New("no driver")
 var ErrWrongVersion = errors.New("wrong version")
 var ErrShouldExist = event.ErrShouldExist
 var ErrShouldNotExist = event.ErrShouldNotExist
+var ErrNotFound = errors.New("not found")
 
 type PA[T any] interface {
 	event.Aggregate

pkg/es/es.graphqls

@@ -20,5 +20,9 @@ type Event implements Edge @goModel(model: "github.com/sour-is/ev/pkg/es.GQLEven
     eventID: String!
     values: Map!
     bytes: String!
+    type: String!
+    created: Time!
     meta: Meta!
+
+    linked: Event
 }

pkg/es/event/events.go

@@ -60,6 +60,9 @@ func (lis Events) StreamID() string {
 func (lis Events) SetStreamID(streamID string) {
 	SetStreamID(streamID, lis...)
 }
+func (lis Events) Count() int64 {
+	return int64(len(lis))
+}
 func (lis Events) First() Event {
 	if len(lis) == 0 {
 		return NilEvent

pkg/es/event/reflect.go

@@ -261,11 +261,30 @@ func Values(e Event) map[string]any {
 			continue
 		}
 
+		omitempty := false
 		field := v.FieldByIndex(idx.Index)
 
 		name := idx.Name
 		if n, ok := idx.Tag.Lookup("json"); ok {
-			name = n
+			var (
+				opt   string
+				found bool
+			)
+
+			name, opt, found = strings.Cut(n, ",")
+			if name == "-" {
+				continue
+			}
+
+			if found {
+				if strings.Contains(opt, "omitempty") {
+					omitempty = true
+				}
+			}
+		}
+
+		if omitempty && field.IsZero() {
+			continue
 		}
 
 		m[name] = field.Interface()

pkg/es/graph.go

@@ -2,6 +2,7 @@ package es
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 	"time"
@@ -15,13 +16,18 @@ type EventResolver interface {
 	Events(ctx context.Context, streamID string, paging *gql.PageInput) (*gql.Connection, error)
 	EventAdded(ctx context.Context, streamID string, after int64) (<-chan *GQLEvent, error)
 }
+type contextKey struct {
+	name string
+}
+
+var esKey = contextKey{"event-store"}
 
 func (es *EventStore) Events(ctx context.Context, streamID string, paging *gql.PageInput) (*gql.Connection, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	lis, err := es.Read(ctx, streamID, paging.GetIdx(0), paging.GetCount(30))
-	if err != nil {
+	if err != nil && !errors.Is(err, ErrNotFound) {
 		span.RecordError(err)
 		return nil, err
 	}
@@ -107,6 +113,14 @@ func (e *EventStore) EventAdded(ctx context.Context, streamID string, after int6
 	return ch, nil
 }
 func (*EventStore) RegisterHTTP(*http.ServeMux) {}
+func (e *EventStore) GetMiddleware() func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			r = r.WithContext(gql.ToContext(r.Context(), esKey, e))
+			next.ServeHTTP(w, r)
+		})
+	}
+}
 
 type GQLEvent struct {
 	e event.Event
@@ -118,6 +132,12 @@ func (e *GQLEvent) ID() string {
 func (e *GQLEvent) EventID() string {
 	return e.e.EventMeta().GetEventID()
 }
+func (e *GQLEvent) Type() string {
+	return event.TypeOf(e.e)
+}
+func (e *GQLEvent) Created() time.Time {
+	return e.e.EventMeta().Created()
+}
 func (e *GQLEvent) Values() map[string]interface{} {
 	return event.Values(e.e)
 }
@@ -129,4 +149,18 @@ func (e *GQLEvent) Meta() *event.Meta {
 	meta := e.e.EventMeta()
 	return &meta
 }
+func (e *GQLEvent) Linked(ctx context.Context) (*GQLEvent, error) {
+	values := event.Values(e.e)
+	streamID, ok := values["stream_id"].(string)
+	if !ok {
+		return nil, nil
+	}
+	pos, ok := values["pos"].(uint64)
+	if !ok {
+		return nil, nil
+	}
+
+	events, err := gql.FromContext[contextKey, *EventStore](ctx, esKey).Read(ctx, streamID, int64(pos)-1, 1)
+	return &GQLEvent{e: events.First()}, err
+}
 func (e *GQLEvent) IsEdge() {}

pkg/gql/common.graphqls

@@ -6,7 +6,8 @@ type Connection @goModel(model: "github.com/sour-is/ev/pkg/gql.Connection") {
     edges: [Edge!]!
 }
 input PageInput  @goModel(model: "github.com/sour-is/ev/pkg/gql.PageInput") {
-    idx: Int = 0
+    after:  Int = 0
+    before: Int
     count:  Int = 30
 }
 type PageInfo  @goModel(model: "github.com/sour-is/ev/pkg/gql.PageInfo") {

pkg/gql/connection.go

@@ -38,19 +38,30 @@ type PageInfo struct {
 }
 
 type PageInput struct {
-	Idx   *int64 `json:"idx"`
+	After  *int64 `json:"after"`
+	Before *int64 `json:"before"`
 	Count  *int64 `json:"count"`
 }
 
 func (p *PageInput) GetIdx(v int64) int64 {
-	if p == nil || p.Idx == nil {
+	if p == nil {
-		return v
+		// pass
+	} else if p.Before != nil {
+		return (*p.Before)
+	} else if p.After != nil {
+		return *p.After
 	}
-	return *p.Idx
+
+	return v
 }
 func (p *PageInput) GetCount(v int64) int64 {
 	if p == nil || p.Count == nil {
 		return v
+	} else if p.Before != nil {
+		return -(*p.Count)
+	} else if p.After != nil {
+		return *p.Count
 	}
+
 	return *p.Count
 }