Fix get msg doc model by index

pkg/common/storage/database/mgo/msg.go

@@ -1,3 +1,17 @@
+// Copyright © 2023 OpenIM. All rights reserved.
+//
+// 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 mgo
 
 import (
@@ -204,9 +218,47 @@ func (m *MsgMgo) GetMsgDocModelByIndex(ctx context.Context, conversationID strin
 	if sort != 1 && sort != -1 {
 		return nil, errs.ErrArgs.WrapMsg("mongo sort must be 1 or -1")
 	}
-	opt := options.Find().SetLimit(1).SetSkip(index).SetSort(bson.M{"doc_id": sort}).SetLimit(1)
-	filter := bson.M{"doc_id": primitive.Regex{Pattern: fmt.Sprintf("^%s:", conversationID)}}
-	msgs, err := mongoutil.Find[*model.MsgDocModel](ctx, m.coll, filter, opt)
+
+	// parepare pipeline
+	pipeline := mongo.Pipeline{
+		{{
+			"$match", bson.D{
+				{"doc_id", bson.M{"$regex": fmt.Sprintf("^%s:", conversationID)}},
+			},
+		}},
+		{{
+			"$project", bson.M{
+				"doc_id": 1,
+				"seqSuffix": bson.M{ // Create a new field to store the converted seqSuffix integer.
+					"$toInt": bson.M{ // $toInt expression
+						"$arrayElemAt": bson.A{ // $arrayElemAt requires an array as the first argument.
+							bson.M{"$split": []interface{}{"$doc_id", ":"}}, // $split expression
+							-1, // Indexing, to take the last element of the array.
+						},
+					},
+				},
+				"msgs": 1,
+			},
+		}},
+		{{
+			"$sort", bson.D{ // Sort by seqSuffix.
+				{"seqSuffix", sort},
+			},
+		}},
+	}
+
+	// If pagination is needed, logic can be added here to dynamically modify the pipeline.
+	if index > 0 {
+		pipeline = append(pipeline, bson.D{{
+			"$skip", index,
+		}})
+	}
+	pipeline = append(pipeline, bson.D{{
+		"$limit", 1, // We only need one document.
+	}})
+
+	// Execute an aggregation query.
+	msgs, err := mongoutil.Aggregate[*model.MsgDocModel](ctx, m.coll, pipeline)
 	if err != nil {
 		return nil, err
 	}

pkg/common/storage/database/mgo/msg_test.go

@@ -0,0 +1,72 @@
+// Copyright © 2023 OpenIM. All rights reserved.
+//
+// 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 mgo
+
+import (
+	"context"
+	"fmt"
+	"github.com/openimsdk/open-im-server/v3/pkg/common/config"
+	"github.com/openimsdk/open-im-server/v3/pkg/common/storage/database"
+	"github.com/openimsdk/tools/db/mongoutil"
+	"testing"
+)
+
+func GetTestDriver(t *testing.T, ctx context.Context) (database.Msg, error) {
+
+	var mongoConf config.Mongo
+	mongoConf.URI = ""
+	mongoConf.Address = []string{"192.168.3.212:37017"}
+	mongoConf.Database = "openIM_v3"
+	mongoConf.Username = "root"
+	mongoConf.Password = "openIM123"
+	mongoConf.MaxPoolSize = 100
+	mongoConf.MaxRetry = 10
+
+	mgocli, err := mongoutil.NewMongoDB(ctx, mongoConf.Build())
+	if err != nil {
+		t.Fatal("NewMongoDB failed: ", err)
+		return nil, err
+	}
+	mongoDB := mgocli.GetDB()
+
+	err = mongoDB.Client().Ping(ctx, nil)
+	if err != nil {
+		t.Fatal("Ping failed: ", err)
+		return nil, err
+	}
+
+	return NewMsgMongo(mongoDB)
+}
+
+func TestMsgMgo_GetMsgDocModelByIndex(t *testing.T) {
+	ctx := context.Background()
+
+	driver, _ := GetTestDriver(t, ctx)
+
+	conversationID := "si_10043_10070"
+	msg, err := driver.GetMsgDocModelByIndex(ctx, conversationID, 0, 1)
+	if err != nil {
+		t.Fatal("GetMsgDocModelByIndex failed: ", err)
+	}
+
+	fmt.Println("GetMsgDocModelByIndex Ascent(1): ", msg.DocID)
+
+	msg2, err := driver.GetMsgDocModelByIndex(ctx, conversationID, 0, -1)
+	if err != nil {
+		t.Fatal("GetMsgDocModelByIndex failed: ", err)
+	}
+
+	fmt.Println("GetMsgDocModelByIndex Descent(-1): ", msg2.DocID)
+}