Migrations are sets of database instructions written in Ruby code that “migrate” the database from one state to another. They contain both instructions for changing to the state, and instructions for changing back. Migrations are useful because they are repeatable, sharable, and help manage versions of the database over time.
- [Instructor] We have created a database…and configured our Rails project to connect to it.…Next we need to add tables to that database…and we're going to do that by writing Rails migrations.…A migration is a set of database instructions.…Those instructions are Ruby code,…which migrates our database from one state into another.…Essentially, they describe database changes.…In our migrations we can create a table, add a column,…change the name of a column, drop a table, and much more.…A migration will contain both…the instructions for moving to a new state…and also instructions for moving back down…to the previous state.…
If a migration has instructions to create a table…when moving forward or up,…it will also include instructions…to allow it to move back down by dropping the table.…If you move up by adding three columns to a table,…then you'll have instructions to move back down…by removing those three columns.…Being able to move in both directions…allows us to migrate in both directions.…We can migrate our database to the newest version…
- Creating and configuring a new Ruby on Rails project
- Generating controllers and views
- Handling server requests
- Using different types of routes
- Rendering and viewing templates
- Generating migrations and models
- Creating, updating, and deleting records
- Finding records with queries
- Understanding relationship types
- Writing controllers for CRUD
- Working with layouts and helpers
- Managing application assets
- Building forms
- Validating data
- Authenticating users
Skill Level Beginner
1. What Is Ruby on Rails?
2. Get Started
3. Controllers, Views, and Dynamic Content
4. Databases and Migrations
5. Models and ActiveRecord
7. CRUD, REST, and Resourceful Routes
8. Controllers and CRUD
9. Layouts, Partials, and View Helpers
12. Data Validation
13. Controller Features
14. User Authentication
15. Improve the Simple CMS
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