feat: add utility commands support (show dbs, show collections, getCollectionNames) (#4)

Add support for MongoDB shell utility commands:
- `show dbs` / `show databases` - list all databases
- `show collections` - list collections in current database
- `db.getCollectionNames()` - list collection names in current database

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: h3n4l

executor.go

@@ -61,6 +61,12 @@ func executeOperation(ctx context.Context, client *mongo.Client, database string
 	switch op.opType {
 	case opFind:
 		return executeFind(ctx, client, database, op)
+	case opShowDatabases:
+		return executeShowDatabases(ctx, client)
+	case opShowCollections:
+		return executeShowCollections(ctx, client, database)
+	case opGetCollectionNames:
+		return executeGetCollectionNames(ctx, client, database)
 	default:
 		return nil, &UnsupportedOperationError{
 			Operation: statement,
@@ -122,3 +128,40 @@ func executeFind(ctx context.Context, client *mongo.Client, database string, op
 		RowCount: len(rows),
 	}, nil
 }
+
+// executeShowDatabases executes a show dbs/databases command.
+func executeShowDatabases(ctx context.Context, client *mongo.Client) (*Result, error) {
+	names, err := client.ListDatabaseNames(ctx, bson.D{})
+	if err != nil {
+		return nil, fmt.Errorf("list databases failed: %w", err)
+	}
+
+	rows := make([]string, len(names))
+	copy(rows, names)
+
+	return &Result{
+		Rows:     rows,
+		RowCount: len(rows),
+	}, nil
+}
+
+// executeShowCollections executes a show collections command.
+func executeShowCollections(ctx context.Context, client *mongo.Client, database string) (*Result, error) {
+	names, err := client.Database(database).ListCollectionNames(ctx, bson.D{})
+	if err != nil {
+		return nil, fmt.Errorf("list collections failed: %w", err)
+	}
+
+	rows := make([]string, len(names))
+	copy(rows, names)
+
+	return &Result{
+		Rows:     rows,
+		RowCount: len(rows),
+	}, nil
+}
+
+// executeGetCollectionNames executes a db.getCollectionNames() command.
+func executeGetCollectionNames(ctx context.Context, client *mongo.Client, database string) (*Result, error) {
+	return executeShowCollections(ctx, client, database)
+}

executor_test.go

@@ -379,3 +379,99 @@ func TestCollectionAccessPatterns(t *testing.T) {
 		})
 	}
 }
+
+func TestShowDatabases(t *testing.T) {
+	client, cleanup := setupTestContainer(t)
+	defer cleanup()
+
+	ctx := context.Background()
+
+	// Create a database by inserting a document
+	_, err := client.Database("mydb").Collection("test").InsertOne(ctx, bson.M{"x": 1})
+	require.NoError(t, err)
+
+	gc := gomongo.NewClient(client)
+
+	tests := []struct {
+		name      string
+		statement string
+	}{
+		{"show dbs", "show dbs"},
+		{"show databases", "show databases"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			result, err := gc.Execute(ctx, "mydb", tc.statement)
+			require.NoError(t, err)
+			require.NotNil(t, result)
+			require.GreaterOrEqual(t, result.RowCount, 1)
+
+			// Check that mydb is in the result
+			found := false
+			for _, row := range result.Rows {
+				if row == "mydb" {
+					found = true
+					break
+				}
+			}
+			require.True(t, found, "expected 'mydb' in database list, got: %v", result.Rows)
+		})
+	}
+}
+
+func TestShowCollections(t *testing.T) {
+	client, cleanup := setupTestContainer(t)
+	defer cleanup()
+
+	ctx := context.Background()
+
+	// Create collections by inserting documents
+	_, err := client.Database("testdb").Collection("users").InsertOne(ctx, bson.M{"name": "alice"})
+	require.NoError(t, err)
+	_, err = client.Database("testdb").Collection("orders").InsertOne(ctx, bson.M{"item": "book"})
+	require.NoError(t, err)
+
+	gc := gomongo.NewClient(client)
+
+	result, err := gc.Execute(ctx, "testdb", "show collections")
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, 2, result.RowCount)
+
+	// Check that both collections are in the result
+	collectionSet := make(map[string]bool)
+	for _, row := range result.Rows {
+		collectionSet[row] = true
+	}
+	require.True(t, collectionSet["users"], "expected 'users' collection")
+	require.True(t, collectionSet["orders"], "expected 'orders' collection")
+}
+
+func TestGetCollectionNames(t *testing.T) {
+	client, cleanup := setupTestContainer(t)
+	defer cleanup()
+
+	ctx := context.Background()
+
+	// Create collections by inserting documents
+	_, err := client.Database("testdb").Collection("products").InsertOne(ctx, bson.M{"name": "widget"})
+	require.NoError(t, err)
+	_, err = client.Database("testdb").Collection("categories").InsertOne(ctx, bson.M{"name": "electronics"})
+	require.NoError(t, err)
+
+	gc := gomongo.NewClient(client)
+
+	result, err := gc.Execute(ctx, "testdb", "db.getCollectionNames()")
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, 2, result.RowCount)
+
+	// Check that both collections are in the result
+	collectionSet := make(map[string]bool)
+	for _, row := range result.Rows {
+		collectionSet[row] = true
+	}
+	require.True(t, collectionSet["products"], "expected 'products' collection")
+	require.True(t, collectionSet["categories"], "expected 'categories' collection")
+}

translator.go

@@ -15,6 +15,9 @@ type operationType int
 const (
 	opUnknown operationType = iota
 	opFind
+	opShowDatabases
+	opShowCollections
+	opGetCollectionNames
 )
 
 // mongoOperation represents a parsed MongoDB operation.
@@ -69,10 +72,7 @@ func (v *mongoShellVisitor) visitStatement(ctx mongodb.IStatementContext) {
 	if ctx.DbStatement() != nil {
 		v.visitDbStatement(ctx.DbStatement())
 	} else if ctx.ShellCommand() != nil {
-		v.err = &UnsupportedOperationError{
-			Operation: ctx.ShellCommand().GetText(),
-			Hint:      "shell commands not yet supported",
-		}
+		v.visitShellCommand(ctx.ShellCommand())
 	}
 }
 
@@ -81,9 +81,20 @@ func (v *mongoShellVisitor) visitDbStatement(ctx mongodb.IDbStatementContext) {
 	case *mongodb.CollectionOperationContext:
 		v.visitCollectionOperation(c)
 	case *mongodb.GetCollectionNamesContext:
+		v.operation.opType = opGetCollectionNames
+	}
+}
+
+func (v *mongoShellVisitor) visitShellCommand(ctx mongodb.IShellCommandContext) {
+	switch ctx.(type) {
+	case *mongodb.ShowDatabasesContext:
+		v.operation.opType = opShowDatabases
+	case *mongodb.ShowCollectionsContext:
+		v.operation.opType = opShowCollections
+	default:
 		v.err = &UnsupportedOperationError{
-			Operation: "getCollectionNames",
-			Hint:      "not yet supported",
+			Operation: ctx.GetText(),
+			Hint:      "unknown shell command",
 		}
 	}
 }
@@ -102,10 +113,7 @@ func (v *mongoShellVisitor) visitCollectionOperation(ctx *mongodb.CollectionOper
 }
 
 func (v *mongoShellVisitor) VisitGetCollectionNames(_ *mongodb.GetCollectionNamesContext) any {
-	v.err = &UnsupportedOperationError{
-		Operation: "getCollectionNames",
-		Hint:      "not yet supported",
-	}
+	v.operation.opType = opGetCollectionNames
 	return nil
 }