Trying out paginated cursortoken variant [UNTESTED]

cursortoken/token.go

@@ -3,12 +3,16 @@ package cursortoken
 import (
 	"encoding/base32"
 	"encoding/json"
-	"go.mongodb.org/mongo-driver/bson/primitive"
 	"gogs.mikescher.com/BlackForestBytes/goext/exerr"
+	"strconv"
 	"strings"
 	"time"
 )
 
+type CursorToken interface {
+	Token() string
+}
+
 type Mode string
 
 const (
@@ -24,97 +28,6 @@ type Extra struct {
 	PageSize  *int
 }
 
-type CursorToken struct {
-	Mode               Mode
-	ValuePrimary       string
-	ValueSecondary     string
-	Direction          SortDirection
-	DirectionSecondary SortDirection
-	PageSize           int
-	Extra              Extra
-}
-
-type cursorTokenSerialize struct {
-	ValuePrimary       *string        `json:"v1,omitempty"`
-	ValueSecondary     *string        `json:"v2,omitempty"`
-	Direction          *SortDirection `json:"dir,omitempty"`
-	DirectionSecondary *SortDirection `json:"dir2,omitempty"`
-	PageSize           *int           `json:"size,omitempty"`
-
-	ExtraTimestamp *time.Time `json:"ts,omitempty"`
-	ExtraId        *string    `json:"id,omitempty"`
-	ExtraPage      *int       `json:"pg,omitempty"`
-	ExtraPageSize  *int       `json:"sz,omitempty"`
-}
-
-func Start() CursorToken {
-	return CursorToken{
-		Mode:               CTMStart,
-		ValuePrimary:       "",
-		ValueSecondary:     "",
-		Direction:          "",
-		DirectionSecondary: "",
-		PageSize:           0,
-		Extra:              Extra{},
-	}
-}
-
-func End() CursorToken {
-	return CursorToken{
-		Mode:               CTMEnd,
-		ValuePrimary:       "",
-		ValueSecondary:     "",
-		Direction:          "",
-		DirectionSecondary: "",
-		PageSize:           0,
-		Extra:              Extra{},
-	}
-}
-
-func (c *CursorToken) Token() string {
-	if c.Mode == CTMStart {
-		return "@start"
-	}
-	if c.Mode == CTMEnd {
-		return "@end"
-	}
-
-	// We kinda manually implement omitempty for the CursorToken here
-	// because omitempty does not work for time.Time and otherwise we would always
-	// get weird time values when decoding a token that initially didn't have an Timestamp set
-	// For this usecase we treat Unix=0 as an empty timestamp
-
-	sertok := cursorTokenSerialize{}
-
-	if c.ValuePrimary != "" {
-		sertok.ValuePrimary = &c.ValuePrimary
-	}
-	if c.ValueSecondary != "" {
-		sertok.ValueSecondary = &c.ValueSecondary
-	}
-	if c.Direction != "" {
-		sertok.Direction = &c.Direction
-	}
-	if c.DirectionSecondary != "" {
-		sertok.DirectionSecondary = &c.DirectionSecondary
-	}
-	if c.PageSize != 0 {
-		sertok.PageSize = &c.PageSize
-	}
-
-	sertok.ExtraTimestamp = c.Extra.Timestamp
-	sertok.ExtraId = c.Extra.Id
-	sertok.ExtraPage = c.Extra.Page
-	sertok.ExtraPageSize = c.Extra.PageSize
-
-	body, err := json.Marshal(sertok)
-	if err != nil {
-		panic(err)
-	}
-
-	return "tok_" + base32.StdEncoding.EncodeToString(body)
-}
-
 func Decode(tok string) (CursorToken, error) {
 	if tok == "" {
 		return Start(), nil
@@ -125,23 +38,31 @@ func Decode(tok string) (CursorToken, error) {
 	if strings.ToLower(tok) == "@end" {
 		return End(), nil
 	}
-
-	if !strings.HasPrefix(tok, "tok_") {
-		return CursorToken{}, exerr.New(exerr.TypeCursorTokenDecode, "could not decode token, missing prefix").Str("token", tok).Build()
+	if strings.ToLower(tok) == "$end" {
+		return PageEnd(), nil
 	}
+	if strings.HasPrefix(tok, "$") && len(tok) > 1 {
+		n, err := strconv.ParseInt(tok[1:], 10, 64)
+		if err != nil {
+			return nil, exerr.Wrap(err, "failed to deserialize token").Str("token", tok).WithType(exerr.TypeCursorTokenDecode).Build()
+		}
+		return Page(int(n)), nil
+	}
+
+	if strings.HasPrefix(tok, "tok_") {
 
 		body, err := base32.StdEncoding.DecodeString(tok[len("tok_"):])
 		if err != nil {
-		return CursorToken{}, err
+			return nil, err
 		}
 
-	var tokenDeserialize cursorTokenSerialize
+		var tokenDeserialize cursorTokenKeySortSerialize
 		err = json.Unmarshal(body, &tokenDeserialize)
 		if err != nil {
-		return CursorToken{}, exerr.Wrap(err, "failed to deserialize token").Str("token", tok).Build()
+			return nil, exerr.Wrap(err, "failed to deserialize token").Str("token", tok).WithType(exerr.TypeCursorTokenDecode).Build()
 		}
 
-	token := CursorToken{Mode: CTMNormal}
+		token := CTKeySort{Mode: CTMNormal}
 
 		if tokenDeserialize.ValuePrimary != nil {
 			token.ValuePrimary = *tokenDeserialize.ValuePrimary
@@ -165,20 +86,8 @@ func Decode(tok string) (CursorToken, error) {
 		token.Extra.PageSize = tokenDeserialize.ExtraPageSize
 
 		return token, nil
-}
 
-func (c *CursorToken) ValuePrimaryObjectId() (primitive.ObjectID, bool) {
-	if oid, err := primitive.ObjectIDFromHex(c.ValuePrimary); err == nil {
-		return oid, true
 	} else {
-		return primitive.ObjectID{}, false
-	}
-}
-
-func (c *CursorToken) ValueSecondaryObjectId() (primitive.ObjectID, bool) {
-	if oid, err := primitive.ObjectIDFromHex(c.ValueSecondary); err == nil {
-		return oid, true
-	} else {
-		return primitive.ObjectID{}, false
+		return nil, exerr.New(exerr.TypeCursorTokenDecode, "could not decode token, missing/unknown prefix").Str("token", tok).Build()
 	}
 }

cursortoken/tokenKeySort.go

@@ -0,0 +1,128 @@
+package cursortoken
+
+import (
+	"encoding/base32"
+	"encoding/json"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+	"time"
+)
+
+type CTKeySort struct {
+	Mode               Mode
+	ValuePrimary       string
+	ValueSecondary     string
+	Direction          SortDirection
+	DirectionSecondary SortDirection
+	PageSize           int
+	Extra              Extra
+}
+
+type cursorTokenKeySortSerialize struct {
+	ValuePrimary       *string        `json:"v1,omitempty"`
+	ValueSecondary     *string        `json:"v2,omitempty"`
+	Direction          *SortDirection `json:"dir,omitempty"`
+	DirectionSecondary *SortDirection `json:"dir2,omitempty"`
+	PageSize           *int           `json:"size,omitempty"`
+
+	ExtraTimestamp *time.Time `json:"ts,omitempty"`
+	ExtraId        *string    `json:"id,omitempty"`
+	ExtraPage      *int       `json:"pg,omitempty"`
+	ExtraPageSize  *int       `json:"sz,omitempty"`
+}
+
+func NewKeySortToken(valuePrimary string, valueSecondary string, direction SortDirection, directionSecondary SortDirection, pageSize int, extra Extra) CursorToken {
+	return CTKeySort{
+		Mode:               CTMNormal,
+		ValuePrimary:       valuePrimary,
+		ValueSecondary:     valueSecondary,
+		Direction:          direction,
+		DirectionSecondary: directionSecondary,
+		PageSize:           pageSize,
+		Extra:              extra,
+	}
+}
+
+func Start() CursorToken {
+	return CTKeySort{
+		Mode:               CTMStart,
+		ValuePrimary:       "",
+		ValueSecondary:     "",
+		Direction:          "",
+		DirectionSecondary: "",
+		PageSize:           0,
+		Extra:              Extra{},
+	}
+}
+
+func End() CursorToken {
+	return CTKeySort{
+		Mode:               CTMEnd,
+		ValuePrimary:       "",
+		ValueSecondary:     "",
+		Direction:          "",
+		DirectionSecondary: "",
+		PageSize:           0,
+		Extra:              Extra{},
+	}
+}
+
+func (c CTKeySort) Token() string {
+
+	if c.Mode == CTMStart {
+		return "@start"
+	}
+	if c.Mode == CTMEnd {
+		return "@end"
+	}
+
+	// We kinda manually implement omitempty for the CursorToken here
+	// because omitempty does not work for time.Time and otherwise we would always
+	// get weird time values when decoding a token that initially didn't have an Timestamp set
+	// For this usecase we treat Unix=0 as an empty timestamp
+
+	sertok := cursorTokenKeySortSerialize{}
+
+	if c.ValuePrimary != "" {
+		sertok.ValuePrimary = &c.ValuePrimary
+	}
+	if c.ValueSecondary != "" {
+		sertok.ValueSecondary = &c.ValueSecondary
+	}
+	if c.Direction != "" {
+		sertok.Direction = &c.Direction
+	}
+	if c.DirectionSecondary != "" {
+		sertok.DirectionSecondary = &c.DirectionSecondary
+	}
+	if c.PageSize != 0 {
+		sertok.PageSize = &c.PageSize
+	}
+
+	sertok.ExtraTimestamp = c.Extra.Timestamp
+	sertok.ExtraId = c.Extra.Id
+	sertok.ExtraPage = c.Extra.Page
+	sertok.ExtraPageSize = c.Extra.PageSize
+
+	body, err := json.Marshal(sertok)
+	if err != nil {
+		panic(err)
+	}
+
+	return "tok_" + base32.StdEncoding.EncodeToString(body)
+}
+
+func (c CTKeySort) valuePrimaryObjectId() (primitive.ObjectID, bool) {
+	if oid, err := primitive.ObjectIDFromHex(c.ValuePrimary); err == nil {
+		return oid, true
+	} else {
+		return primitive.ObjectID{}, false
+	}
+}
+
+func (c CTKeySort) valueSecondaryObjectId() (primitive.ObjectID, bool) {
+	if oid, err := primitive.ObjectIDFromHex(c.ValueSecondary); err == nil {
+		return oid, true
+	} else {
+		return primitive.ObjectID{}, false
+	}
+}

cursortoken/tokenPaginate.go

@@ -0,0 +1,33 @@
+package cursortoken
+
+import "strconv"
+
+type CTPaginated struct {
+	Mode Mode
+	Page int
+}
+
+func Page(p int) CursorToken {
+	return CTPaginated{
+		Mode: CTMNormal,
+		Page: p,
+	}
+}
+
+func PageEnd() CursorToken {
+	return CTPaginated{
+		Mode: CTMEnd,
+		Page: 0,
+	}
+}
+
+func (c CTPaginated) Token() string {
+	if c.Mode == CTMStart {
+		return "$1"
+	}
+	if c.Mode == CTMEnd {
+		return "$end"
+	}
+
+	return "$" + strconv.Itoa(c.Page)
+}

wmo/collection.go

@@ -120,25 +120,25 @@ func (c *Coll[TData]) createToken(fieldPrimary string, dirPrimary ct.SortDirecti
 
 	valuePrimary, err := c.getFieldValueAsTokenString(lastEntity, fieldPrimary)
 	if err != nil {
-		return ct.CursorToken{}, exerr.Wrap(err, "failed to get (primary) field-value as token-string").Type("lastEntity", lastEntity).Str("fieldPrimary", fieldPrimary).Build()
+		return nil, exerr.Wrap(err, "failed to get (primary) field-value as token-string").Type("lastEntity", lastEntity).Str("fieldPrimary", fieldPrimary).Build()
 	}
 
 	valueSeconary := ""
 	if fieldSecondary != nil && dirSecondary != nil {
 		valueSeconary, err = c.getFieldValueAsTokenString(lastEntity, *fieldSecondary)
 		if err != nil {
-			return ct.CursorToken{}, exerr.Wrap(err, "failed to get (secondary) field-value as token-string").Type("lastEntity", lastEntity).StrPtr("fieldSecondary", fieldSecondary).Build()
+			return nil, exerr.Wrap(err, "failed to get (secondary) field-value as token-string").Type("lastEntity", lastEntity).StrPtr("fieldSecondary", fieldSecondary).Build()
 		}
 	}
 
-	return ct.CursorToken{
-		Mode:           ct.CTMNormal,
-		ValuePrimary:   valuePrimary,
-		ValueSecondary: valueSeconary,
-		Direction:      dirPrimary,
-		PageSize:       langext.Coalesce(pageSize, 0),
-		Extra:          ct.Extra{},
-	}, nil
+	return ct.NewKeySortToken(
+		valuePrimary,
+		valueSeconary,
+		dirPrimary,
+		dirPrimary,
+		langext.Coalesce(pageSize, 0),
+		ct.Extra{},
+	), nil
 }
 
 func (c *Coll[TData]) needsDoubleSort(ctx context.Context) bool {

wmo/queryList.go

@@ -10,6 +10,24 @@ import (
 )
 
 func (c *Coll[TData]) List(ctx context.Context, filter ct.Filter, pageSize *int, inTok ct.CursorToken) ([]TData, ct.CursorToken, error) {
+	if ctks, ok := inTok.(ct.CTKeySort); ok {
+		d, tok, err := c.listWithKSToken(ctx, filter, pageSize, ctks)
+		if err != nil {
+			return nil, ct.End(), err
+		}
+		return d, tok, nil
+	} else if ctks, ok := inTok.(ct.CTPaginated); ok {
+		d, tok, err := c.listWithPaginatedToken(ctx, filter, pageSize, ctks)
+		if err != nil {
+			return nil, ct.End(), err
+		}
+		return d, tok, nil
+	} else {
+		return nil, ct.End(), exerr.New(exerr.TypeCursorTokenDecode, "unknown ct type").Any("token", inTok).Type("tokenType", inTok).Build()
+	}
+}
+
+func (c *Coll[TData]) listWithKSToken(ctx context.Context, filter ct.Filter, pageSize *int, inTok ct.CTKeySort) ([]TData, ct.CursorToken, error) {
 	if inTok.Mode == ct.CTMEnd {
 		return make([]TData, 0), ct.End(), nil
 	}
@@ -41,7 +59,7 @@ func (c *Coll[TData]) List(ctx context.Context, filter ct.Filter, pageSize *int,
 
 	paginationPipeline, doubleSortPipeline, err := createPaginationPipeline(c, inTok, sortPrimary, sortDirPrimary, sortSecondary, sortDirSecondary, pageSize)
 	if err != nil {
-		return nil, ct.CursorToken{}, exerr.
+		return nil, nil, exerr.
 			Wrap(err, "failed to create pagination").
 			WithType(exerr.TypeCursorTokenDecode).
 			Str("collection", c.Name()).
@@ -66,7 +84,7 @@ func (c *Coll[TData]) List(ctx context.Context, filter ct.Filter, pageSize *int,
 
 	cursor, err := c.coll.Aggregate(ctx, pipeline)
 	if err != nil {
-		return nil, ct.CursorToken{}, exerr.Wrap(err, "mongo-aggregation failed").Any("pipeline", pipeline).Str("collection", c.Name()).Build()
+		return nil, nil, exerr.Wrap(err, "mongo-aggregation failed").Any("pipeline", pipeline).Str("collection", c.Name()).Build()
 	}
 
 	defer func() { _ = cursor.Close(ctx) }()
@@ -75,7 +93,7 @@ func (c *Coll[TData]) List(ctx context.Context, filter ct.Filter, pageSize *int,
 	if pageSize == nil {
 		entries, err := c.decodeAll(ctx, cursor)
 		if err != nil {
-			return nil, ct.CursorToken{}, exerr.Wrap(err, "failed to all-decode entities").Build()
+			return nil, nil, exerr.Wrap(err, "failed to all-decode entities").Build()
 		}
 		return entries, ct.End(), nil
 	}
@@ -85,7 +103,7 @@ func (c *Coll[TData]) List(ctx context.Context, filter ct.Filter, pageSize *int,
 		var entry TData
 		entry, err = c.decodeSingle(ctx, cursor)
 		if err != nil {
-			return nil, ct.CursorToken{}, exerr.Wrap(err, "failed to decode entity").Build()
+			return nil, nil, exerr.Wrap(err, "failed to decode entity").Build()
 		}
 		entities = append(entities, entry)
 	}
@@ -100,12 +118,70 @@ func (c *Coll[TData]) List(ctx context.Context, filter ct.Filter, pageSize *int,
 
 	nextToken, err := c.createToken(sortPrimary, sortDirPrimary, sortSecondary, sortDirSecondary, last, pageSize)
 	if err != nil {
-		return nil, ct.CursorToken{}, exerr.Wrap(err, "failed to create (out)-token").Build()
+		return nil, nil, exerr.Wrap(err, "failed to create (out)-token").Build()
 	}
 
 	return entities, nextToken, nil
 }
 
+func (c *Coll[TData]) listWithPaginatedToken(ctx context.Context, filter ct.Filter, pageSize *int, inTok ct.CTPaginated) ([]TData, ct.CursorToken, error) {
+	var err error
+
+	page := inTok.Page
+
+	if page < 0 {
+		page = 1
+	}
+
+	pipelineSort := mongo.Pipeline{}
+	pipelineFilter := mongo.Pipeline{}
+
+	if filter != nil {
+		pipelineFilter = filter.FilterQuery(ctx)
+		pf1, pd1, pf2, pd2 := filter.Pagination(ctx)
+
+		pipelineSort, err = createSortOnlyPipeline(pf1, pd1, &pf2, &pd2)
+		if err != nil {
+			return nil, nil, exerr.Wrap(err, "failed to create sort pipeline").Build()
+		}
+	}
+
+	pipelinePaginate := mongo.Pipeline{}
+	if pageSize != nil {
+		pipelinePaginate = append(pipelinePaginate, bson.D{{Key: "$skip", Value: *pageSize * (page - 1)}})
+		pipelinePaginate = append(pipelinePaginate, bson.D{{Key: "$limit", Value: *pageSize}})
+	} else {
+		page = 1
+	}
+
+	pipelineCount := mongo.Pipeline{}
+	pipelineCount = append(pipelineCount, bson.D{{Key: "$count", Value: "count"}})
+
+	extrModPipelineResolved := mongo.Pipeline{}
+	for _, ppl := range c.extraModPipeline {
+		extrModPipelineResolved = langext.ArrConcat(extrModPipelineResolved, ppl(ctx))
+	}
+
+	pipelineList := langext.ArrConcat(pipelineFilter, pipelineSort, pipelinePaginate, extrModPipelineResolved, pipelineSort)
+
+	cursorList, err := c.coll.Aggregate(ctx, pipelineList)
+	if err != nil {
+		return nil, nil, exerr.Wrap(err, "mongo-aggregation failed").Any("pipeline", pipelineList).Str("collection", c.Name()).Build()
+	}
+
+	entities, err := c.decodeAll(ctx, cursorList)
+	if err != nil {
+		return nil, nil, exerr.Wrap(err, "failed to all-decode entities").Build()
+	}
+
+	tokOut := ct.Page(page + 1)
+	if pageSize == nil || len(entities) < *pageSize {
+		tokOut = ct.PageEnd()
+	}
+
+	return entities, tokOut, nil
+}
+
 func (c *Coll[TData]) Count(ctx context.Context, filter ct.RawFilter) (int64, error) {
 	type countRes struct {
 		Count int64 `bson:"c"`
@@ -138,12 +214,12 @@ func (c *Coll[TData]) ListWithCount(ctx context.Context, filter ct.Filter, pageS
 	// NOTE: Possible optimization: Cache count in CursorToken, then fetch count only on first page.
 	count, err := c.Count(ctx, filter)
 	if err != nil {
-		return nil, ct.CursorToken{}, 0, err
+		return nil, nil, 0, err
 	}
 
 	data, token, err := c.List(ctx, filter, pageSize, inTok)
 	if err != nil {
-		return nil, ct.CursorToken{}, 0, err
+		return nil, nil, 0, err
 	}
 	return data, token, count, nil
 }
@@ -184,7 +260,7 @@ func (c *Coll[TData]) ListAllIDs(ctx context.Context, filter ct.RawFilter) ([]st
 	return langext.ArrMap(res, func(v idObject) string { return v.ID }), nil
 }
 
-func createPaginationPipeline[TData any](coll *Coll[TData], token ct.CursorToken, fieldPrimary string, sortPrimary ct.SortDirection, fieldSecondary *string, sortSecondary *ct.SortDirection, pageSize *int) ([]bson.D, []bson.D, error) {
+func createPaginationPipeline[TData any](coll *Coll[TData], token ct.CTKeySort, fieldPrimary string, sortPrimary ct.SortDirection, fieldSecondary *string, sortSecondary *ct.SortDirection, pageSize *int) ([]bson.D, []bson.D, error) {
 
 	cond := bson.A{}
 	sort := bson.D{}
@@ -265,3 +341,33 @@ func createPaginationPipeline[TData any](coll *Coll[TData], token ct.CursorToken
 
 	return pipeline, pipelineSort, nil
 }
+
+func createSortOnlyPipeline(fieldPrimary string, sortPrimary ct.SortDirection, fieldSecondary *string, sortSecondary *ct.SortDirection) ([]bson.D, error) {
+
+	sort := bson.D{}
+
+	if sortPrimary == ct.SortASC {
+		// We sort ASC on <field> - so we want all entries newer ($gt) than the $primary
+		sort = append(sort, bson.E{Key: fieldPrimary, Value: +1})
+	} else if sortPrimary == ct.SortDESC {
+		// We sort DESC on <field> - so we want all entries older ($lt) than the $primary
+		sort = append(sort, bson.E{Key: fieldPrimary, Value: -1})
+	}
+
+	if fieldSecondary != nil && sortSecondary != nil && *fieldSecondary != fieldPrimary {
+
+		if *sortSecondary == ct.SortASC {
+
+			sort = append(sort, bson.E{Key: *fieldSecondary, Value: +1})
+
+		} else if *sortSecondary == ct.SortDESC {
+
+			sort = append(sort, bson.E{Key: *fieldSecondary, Value: -1})
+
+		}
+	}
+
+	pipelineSort := mongo.Pipeline{bson.D{{Key: "$sort", Value: sort}}}
+
+	return pipelineSort, nil
+}