Trying out paginated cursortoken variant [UNTESTED]

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
+}