diff --git a/adapter.go b/adapter.go
index 6351ff1..8c44cb9 100644
--- a/adapter.go
+++ b/adapter.go
@@ -157,13 +157,19 @@ func NewAdapterByDB(client *mongo.Client, config *AdapterConfig) (persist.BatchA
 		config.Timeout = defaultTimeout
 	}
 
+	collection := client.Database(config.DatabaseName).Collection(config.CollectionName)
+
 	a := &adapter{
 		client:     client,
-		collection: client.Database(config.DatabaseName).Collection(config.CollectionName),
+		collection: collection,
 		timeout:    config.Timeout,
 		filtered:   config.IsFiltered,
 	}
 
+	if err := a.prepareIndexes(); err != nil {
+		return nil, err
+	}
+
 	// Call the destructor when the object is released.
 	runtime.SetFinalizer(a, finalizer)
 
@@ -185,6 +191,14 @@ func (a *adapter) open(clientOption *options.ClientOptions, databaseName string,
 	a.client = client
 	a.collection = collection
 
+	if err = a.prepareIndexes(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (a *adapter) prepareIndexes() error {
 	indexes := []string{"ptype", "v0", "v1", "v2", "v3", "v4", "v5"}
 	keysDoc := bson.D{}
 
@@ -195,7 +209,7 @@ func (a *adapter) open(clientOption *options.ClientOptions, databaseName string,
 		keysDoc = append(keysDoc, keyDoc)
 	}
 
-	if _, err = collection.Indexes().CreateOne(
+	if _, err := a.collection.Indexes().CreateOne(
 		context.Background(),
 		mongo.IndexModel{
 			Keys:    keysDoc,
diff --git a/go.mod b/go.mod
index 39d4e0f..15dbcfc 100644
--- a/go.mod
+++ b/go.mod
@@ -6,3 +6,17 @@ require (
 	github.com/casbin/casbin/v2 v2.71.1
 	go.mongodb.org/mongo-driver v1.12.0
 )
+
+require (
+	github.com/Knetic/govaluate v3.0.1-0.20171022003610-9aa49832a739+incompatible // indirect
+	github.com/golang/snappy v0.0.1 // indirect
+	github.com/klauspost/compress v1.13.6 // indirect
+	github.com/montanaflynn/stats v0.0.0-20171201202039-1bf9dbcd8cbe // indirect
+	github.com/xdg-go/pbkdf2 v1.0.0 // indirect
+	github.com/xdg-go/scram v1.1.2 // indirect
+	github.com/xdg-go/stringprep v1.0.4 // indirect
+	github.com/youmark/pkcs8 v0.0.0-20181117223130-1be2e3e5546d // indirect
+	golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d // indirect
+	golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4 // indirect
+	golang.org/x/text v0.7.0 // indirect
+)