CODEWITHSUNDEEP
ruby-on-railssvnmigrationrails-migrations
salt.racer
salt.racer

Reputation: 22352

Managing Rails Migrations for different branches on the same machine

I'm a one-man-band at the company I work for. I develop a Rails application for internal use within the company. Since the beginning of the project I have used SVN for source control and done most, but not all, development in trunk. Occasionally, when I have had very significant changes to make, I have branched and made the changes merging back in when done. All very typical.

However, none of those "significant changes" that I have had to make have ever touched the database migrations. They have always been view/controller stuff.

In this situation, with one development box, how do I play around with migrations and various database changes that I may or may not keep? I don't want to have to remember to revert all the migrations back to the beginning of the branch before I throw the branch out if it doesn't work.

I have considered setting up special development environments and databases (app_branch instead of app_development) but that seems to work strongly against the notion of "easy branching" that experimental development tends to rely on.

Are there best practices for this situation? What are others out there doing in this situation?

Upvotes: 7

Views: 1917

Answers (5)

Marnen Laibow-Koser
Marnen Laibow-Koser

Reputation: 6337

Make sure your schema.rb file is in version control. That way, as you switch branches, you can drop your DB and then do rake db:schema:load as necessary.

Also, you really should switch to Git. It will make branch management a lot easier than SVN. (I speak from lots of experience with both programs.)

Upvotes: 2

Sky
Sky

Reputation: 4853

I wrote a script for dealing with this exact problem. It is based around git, but you could easily change it to work for svn:

https://gist.github.com/4076864

Given a branch name it will:

  1. Roll back any migrations on your current branch which do not exist on the given branch
  2. Discard any changes to the db/schema.rb file
  3. Check out the given branch
  4. Run any new migrations existing in the given branch
  5. Update your test database

I find myself manually doing this all the time on our project, so I thought it'd be nice to automate the process.

Upvotes: 1

Brian Glick
Brian Glick

Reputation: 2201

If I am creating a branch where you are making siginificant changes, you can create a copy of the database before creating your migrations then change the development section of database.yml inside the branch. Leave your :production section alone and then decide which version of the database you want to keep for future development when you merge the branch back into the trunk.

We do this with feature releases. I'll have local DBs for version 1, 2, 3 like "db_v1", db_v2", etc. As we roll through the versions, each subsequent development branch gets an edit in database.yml while the trunk stays on the last version for bug fixing.

Upvotes: 0

Surya
Surya

Reputation: 53

I try hard to keep my development database "droppable." If I lose it all - no big deal. My migrations are ready to build it up again from scratch and there's always a script with seed / test data in it somewhere. I guess it's not especially clever.

If I needed a new branch for database work, I would just check it out, drop, create, rake, and then seed. I guess I'd write a script to get it done because when I go to adandon the branch, I'm going to have to go through the same process again from the trunk.

Upvotes: 3

Doug R
Doug R

Reputation: 5779

Well, if you want to have different schemas, you'll need multiple databases. "Easy branching" refers to source control, typically, and not databases. As far as I know there's no easy way to branch databases like you would branch in, say, git.

One thing we do to manage our dev/production branches is we check our current git branch in our database.yml file. If the current branch is production, we use one database, otherwise we use our dev database. something along the lines of this:

<% if 'git branch' =~ /^\* production/
    db = 'production_database'
   else
    db = 'development_database
end %>

development:
    database: <% db %>

Note, the 'production_database' refers to a local version of the production schema, not the live production database.

Upvotes: 1

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