golang-migrate-objects

Overview

golang-migrate-objects is a Go-based tool that extends golang-migrate to manage database objects. It allows for migrations of complex database objects by applying structured steps. It includes automatic generation of files for object creation and dropping, helping maintain consistency across versions.

Main features

• Supports both up and down migrations with database objects.
• Can automatically generate a "sum file" that merges the latest versions of DB objects.
• Utilizes a configuration structure to define paths and database settings.
• Supports command-line arguments to control migration actions and file management.

Project structure

• main.go: Initializes configuration and manages command-line interface.
• /migrator/migrator.go: Contains core migration logic for managing DB objects.
• /migrator/types.go: Defines data structures used in the migrator.

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Configuration Structure

Config Struct (in /migrator/types.go)

Field	Type	Description
DB	*sql.DB	Database connection instance.
PriorityLpad	int	Padding length for priority fields.
VersionLpad	int	Padding length for version fields.
MigrationFilesPath	string	Path to SQL migration files.
DbObjectPath	string	Path to DB object files.
CreateObjectsFilename	string	Filename for creating merged sum files.
DropObjectsFilename	string	Filename for object drop scripts.

Usage instructions

1. Set Up Migration Paths
   • mpath: Path to migration files.
   • obj_path: Path to DB object files.
   • db_source: Database connection string.
2. Execute commands
   • Run commands with go run main.go with flags to define migration behavior: go run main.go -mpath=<migration_path> -obj_path=<object_path> -db_source=<db_source>

Available Command-Line Flags

Flag	Type	Description
-mpath	string	Path to SQL migration files. Required
-obj_path	string	Path to DB object files. Required
-db_source	string	Database connection string. Required
-co_filename	string	Filename for generating the sum file. Required
-do_filename	string	Filename for object drop scripts. Required
-sumfile	bool	If set, creates a sum file of all object versions.
-up	bool	Runs migrations in the up direction.
-down	bool	Runs migrations in the down direction.
-step	int	Number of steps to migrate. If 0, runs all migrations.

Core Components

Migrator Struct (in /migrator/migrator.go)

Field	Type	Description
Migrate	*migrate.Migrate	Instance for migration operations.
Config	*Config	Configuration settings from the Config struct.

Methods in Migrator

• GetObjectList: Returns a list of DB objects based on the directory structure.
• GetObjectsForStep: Retrieves DB objects for a specific migration step, considering direction.
• CreateObjectsForStep: Creates objects required for a specific step.
• CreateObjectsFile: Merges latest versions of DB objects into a single file.
• DropObjects: Executes a script to drop DB objects.
• RunFile: Executes SQL file at the specified path.
• RunAll: Migrates the database to the highest available version.

Additional Helper Functions

• parseDir and parseVersionFiles: Parses directories and files to extract object versions.
• orderDirEntries: Orders directory entries by name.

Example usage

1. Run All Migrations Up

go run main.go -mpath="path/to/migrations" -obj_path="path/to/objects" -db_source="postgres://user:pass@host/db" -up

2. Generate a Sum File

go run main.go -mpath="path/to/migrations" -obj_path="path/to/objects" -db_source="postgres://user:pass@host/db" -sumfile

Error Handling

The package includes several error checks, such as:

• ErrDifferentPriorityLength: Ensures all priority values are of equal length.
• ErrInvalidPriority: Ensures priority values are valid integers.
• ErrDifferentVersionLength: Checks if all version numbers have consistent lengths.