Rake: A basic intro of Rake and db migration using rake

Rake is a simple ruby build program with capabilities similar to make. Rake has the following features:

• Rakefiles (rake‘s version of Makefiles) are completely defined in standard Ruby syntax. No XML files to edit. No quirky Makefile syntax to worry about (is that a tab or a space?)
• Users can specify tasks with prerequisites.
• Rake supports rule patterns to synthesize implicit tasks.
• Flexible FileLists? that act like arrays but know about manipulating file names and paths.
• A library of prepackaged tasks to make building rakefiles easier.

You can get the tasks lists by executing ruby --tasks a selective approach of previous would be ruby --tasks db which shows all the tasks associated with db

• rake db:fixtures:load # Load fixtures into the current environment's database. Load specific fixtures using FIXTURES=x,y
• rake db:migrate # Migrate the database through scripts in db/migrate. Target specific version with VERSION=x
• rake db:remove_unknown # Remove all migrations in db/migrate that is missing from ENVMIGRATION_DIR? directory
• rake db:schema:dump # Create a db/schema.rb file that can be portably used against any DB supported by AR
• rake db:schema:load # Load a schema.rb file into the database
• rake db:sessions:clear # Clear the sessions table
• rake db:sessions:create # Creates a sessions table for use with CGI::Session::ActiveRecordStore?
• rake db:status # Display schema status in parsable YAML format
• rake db:structure:dump # Dump the database structure to a SQL file
• rake db:test:clone # Recreate the test database from the current environment's database schema
• rake db:test:clone_structure # Recreate the test databases from the development structure
• rake db:test:prepare # Prepare the test database and load the schema
• rake db:test:purge # Empty the test database
• rake db:unmigrate # Remove a specific migration based on MIGRATION_FILE (no validation is done)

Migration

• rake db:migrate : (Migrate the database through scripts in db/migrate. Target specific version with VERSION=x)
• Generate script for your acction example: script/generate migration DummyMigration?
• it creates a file something like 01211257749_dummy_migration.rb in the directory vim db/migrate/
• and also makes an entry in history.txt in the same folder do vim db/migrate/history.txt to check that

Unmigration

• Revert back your changes using the following syntax

rake db:unmigrate MIGRATION_FILE=db/migrate/01211257749_dummy_migration.rb
rake --tasks db

Structure Dump

• Syntax: rake db:structure:dump * creates a file something like development_structure.sql on the db folder * you can change the default schema by modifying the database config file
• cd config/
• vim database.yml
• rake db:structure:dump RAILS_ENV=production
• creates a structure dump for vim production_structure.sql