Join Kevin Skoglund for an in-depth discussion in this video Solving migration problems, part of Ruby on Rails 4 Essential Training.
…Migrations make managing your database schema easy.…However, problems can occur while we're running our migrations…if we run into a bug in our migration code.…It can leave your migrations in a broken…state where we can't migrate either up or down.…It's important to learn how this happens…and resolve these problems when they occur.…To demonstrate, I need to create a bug in my migration code.…Let's start by first migrating our database back to the basics.…Rake db migrate version equals zero.…
I've now taken my database all the way down.…I have no user table and none of my migration are in effect.…Let's open my migration for alter users.…And for the rename column method, let's change the column from password to broken.…Let's save that file.…And of course that column doesn't exist, so it's going…to give us an error in the middle of our migration.…Let's try it out.…Go back to the command line, Rake, DB, Migrate.…The first two migrations run successfully.…They execute and then their migration version…number gets added to the schema migration's table.…
- Why use Ruby on Rails?
- Installing Ruby on Rails on Mac and Windows
- Rendering templates and redirecting requests
- Generating and running database migrations
- Creating, updating, and deleting records
- Understanding association types
- Using layouts, partials, and view helpers
- Incorporating assets using asset pipeline
- Validating form data
- Authenticating users and managing user access
- Architecting RESTful applications
- Debugging and error handing
Skill Level Intermediate
1. What Is Ruby on Rails?
2. Installing Ruby on Rails on a Mac
3. Installing Ruby on Rails on a Windows Machine
4. Getting Started
5. Controllers, Views, and Dynamic Content
6. Databases and Migrations
7. Models, ActiveRecord, and ActiveRelation
9. Controllers and CRUD
10. Layouts, Partials, and View Helpers
13. Data Validation
14. User Authentication
15. Improving the Simple CMS
16. REST and RESTful Routes
17. Debugging and Error Handling
18. Introducing More Advanced Topics
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