feat(relations): 🎉 add flatten schema option for output

* Introduce `--flatten-schema` flag to convert, merge, and split commands.
* Modify database writing functions to support flattened schema names.
* Update template functions to handle schema.table naming convention.
* Enhance PostgreSQL writer to utilize flattened schema in generated SQL.
* Update tests to ensure compatibility with new flattening feature.
* Dependencies updated for improved functionality.

cmd/relspec/merge.go

@@ -56,6 +56,7 @@ var (
 	mergeSkipTables    string // Comma-separated table names to skip
 	mergeVerbose       bool
 	mergeReportPath    string // Path to write merge report
+	mergeFlattenSchema bool
 )
 
 var mergeCmd = &cobra.Command{
@@ -123,6 +124,7 @@ func init() {
 	mergeCmd.Flags().StringVar(&mergeSkipTables, "skip-tables", "", "Comma-separated list of table names to skip during merge")
 	mergeCmd.Flags().BoolVar(&mergeVerbose, "verbose", false, "Show verbose output")
 	mergeCmd.Flags().StringVar(&mergeReportPath, "merge-report", "", "Path to write merge report (JSON format)")
+	mergeCmd.Flags().BoolVar(&mergeFlattenSchema, "flatten-schema", false, "Flatten schema.table names to schema_table (useful for databases like SQLite that do not support schemas)")
 }
 
 func runMerge(cmd *cobra.Command, args []string) error {
@@ -237,7 +239,7 @@ func runMerge(cmd *cobra.Command, args []string) error {
 		fmt.Fprintf(os.Stderr, "      Path:   %s\n", mergeOutputPath)
 	}
 
-	err = writeDatabaseForMerge(mergeOutputType, mergeOutputPath, mergeOutputConn, targetDB, "Output")
+	err = writeDatabaseForMerge(mergeOutputType, mergeOutputPath, mergeOutputConn, targetDB, "Output", mergeFlattenSchema)
 	if err != nil {
 		return fmt.Errorf("failed to write output: %w", err)
 	}
@@ -324,7 +326,7 @@ func readDatabaseForMerge(dbType, filePath, connString, label string) (*models.D
 	return db, nil
 }
 
-func writeDatabaseForMerge(dbType, filePath, connString string, db *models.Database, label string) error {
+func writeDatabaseForMerge(dbType, filePath, connString string, db *models.Database, label string, flattenSchema bool) error {
 	var writer writers.Writer
 
 	switch strings.ToLower(dbType) {
@@ -332,59 +334,59 @@ func writeDatabaseForMerge(dbType, filePath, connString string, db *models.Datab
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for DBML format", label)
 		}
-		writer = wdbml.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wdbml.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "dctx":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for DCTX format", label)
 		}
-		writer = wdctx.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wdctx.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "drawdb":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for DrawDB format", label)
 		}
-		writer = wdrawdb.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wdrawdb.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "graphql":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for GraphQL format", label)
 		}
-		writer = wgraphql.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wgraphql.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "json":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for JSON format", label)
 		}
-		writer = wjson.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wjson.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "yaml":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for YAML format", label)
 		}
-		writer = wyaml.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wyaml.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "gorm":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for GORM format", label)
 		}
-		writer = wgorm.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wgorm.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "bun":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for Bun format", label)
 		}
-		writer = wbun.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wbun.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "drizzle":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for Drizzle format", label)
 		}
-		writer = wdrizzle.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wdrizzle.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "prisma":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for Prisma format", label)
 		}
-		writer = wprisma.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wprisma.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "typeorm":
 		if filePath == "" {
 			return fmt.Errorf("%s: file path is required for TypeORM format", label)
 		}
-		writer = wtypeorm.NewWriter(&writers.WriterOptions{OutputPath: filePath})
+		writer = wtypeorm.NewWriter(&writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema})
 	case "pgsql":
-		writerOpts := &writers.WriterOptions{OutputPath: filePath}
+		writerOpts := &writers.WriterOptions{OutputPath: filePath, FlattenSchema: flattenSchema}
 		if connString != "" {
 			writerOpts.Metadata = map[string]interface{}{
 				"connection_string": connString,