Implement $sort aggregation pipeline stage (#2093)

FerretDB · Mar 1, 2023 · dfd46b3 · dfd46b3
1 parent 1fa849f
commit dfd46b3
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Showing 5 changed files with 96 additions and 20 deletions.
diff --git a/internal/handlers/common/aggregations/match.go b/internal/handlers/common/aggregations/match.go
@@ -18,6 +18,7 @@ import (
 	"context"
 
 	"github.com/FerretDB/FerretDB/internal/handlers/common"
+	"github.com/FerretDB/FerretDB/internal/handlers/commonerrors"
 	"github.com/FerretDB/FerretDB/internal/types"
 )
 
@@ -30,7 +31,11 @@ type match struct {
 func newMatch(stage *types.Document) (Stage, error) {
 	filter, err := common.GetRequiredParam[*types.Document](stage, "$match")
 	if err != nil {
-		return nil, err
+		return nil, commonerrors.NewCommandErrorMsgWithArgument(
+			commonerrors.ErrMatchBadExpression,
+			"the match filter must be an expression in an object",
+			"aggregate",
+		)
 	}
 
 	return &match{
@@ -58,5 +63,5 @@ func (m *match) Process(ctx context.Context, in []*types.Document) ([]*types.Doc
 
 // check interfaces
 var (
-	_ Stage = (*count)(nil)
+	_ Stage = (*match)(nil)
 )
diff --git a/internal/handlers/common/aggregations/sort.go b/internal/handlers/common/aggregations/sort.go
@@ -0,0 +1,60 @@
+// Copyright 2021 FerretDB Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package aggregations
+
+import (
+	"context"
+
+	"github.com/FerretDB/FerretDB/internal/handlers/common"
+	"github.com/FerretDB/FerretDB/internal/handlers/commonerrors"
+	"github.com/FerretDB/FerretDB/internal/types"
+)
+
+// sort represents $sort stage.
+type sort struct {
+	fields *types.Document
+}
+
+// newSort creates a new $sort stage.
+func newSort(stage *types.Document) (Stage, error) {
+	fields, err := common.GetRequiredParam[*types.Document](stage, "$sort")
+	if err != nil {
+		return nil, commonerrors.NewCommandErrorMsgWithArgument(
+			commonerrors.ErrSortBadExpression,
+			"the $sort key specification must be an object",
+			"aggregate",
+		)
+	}
+
+	// TODO: https://github.com/FerretDB/FerretDB/issues/2090
+
+	return &sort{
+		fields: fields,
+	}, nil
+}
+
+// Process implements Stage interface.
+func (m *sort) Process(ctx context.Context, in []*types.Document) ([]*types.Document, error) {
+	if err := common.SortDocuments(in, m.fields); err != nil {
+		return nil, err
+	}
+
+	return in, nil
+}
+
+// check interfaces
+var (
+	_ Stage = (*sort)(nil)
+)
diff --git a/internal/handlers/common/aggregations/stage.go b/internal/handlers/common/aggregations/stage.go
@@ -26,10 +26,10 @@ import (
 type newStageFunc func(stage *types.Document) (Stage, error)
 
 // Stage is a common interface for all aggregation stages.
-//
 // TODO use iterators instead of slices of documents
 // https://github.com/FerretDB/FerretDB/issues/1889.
 type Stage interface {
+	// Process applies an aggregate stage on `in` document, it could modify `in` in-place.
 	Process(ctx context.Context, in []*types.Document) ([]*types.Document, error)
 }
 
@@ -38,6 +38,7 @@ var stages = map[string]newStageFunc{
 	// sorted alphabetically
 	"$count": newCount,
 	"$match": newMatch,
+	"$sort":  newSort,
 }
 
 // NewStage creates a new aggregation stage.

diff --git a/internal/handlers/commonerrors/error.go b/internal/handlers/commonerrors/error.go
@@ -86,6 +86,12 @@ const (
 	// ErrDuplicateKey indicates duplicate key violation.
 	ErrDuplicateKey = ErrorCode(11000) // Location11000
 
+	// ErrMatchBadExpression indicates match filter is not object.
+	ErrMatchBadExpression = ErrorCode(15959)
+
+	// ErrSortBadExpression indicates sort expression is not object.
+	ErrSortBadExpression = ErrorCode(15973)
+
 	// ErrSortBadValue indicates bad value in sort input.
 	ErrSortBadValue = ErrorCode(15974) // Location15974
 

diff --git a/internal/handlers/commonerrors/errorcode_string.go b/internal/handlers/commonerrors/errorcode_string.go