Monday, November 13, 2006
Rails: Get the schema_info version number from Rake
Recently a coworker asked if there was a simple way to get the current version out of the schema_info table. Of course, one simple answer is to simply look in the database.
However, if you want to quickly pull the version from a command line, this rake task should do the trick*:
However, if you want to quickly pull the version from a command line, this rake task should do the trick*:
namespace :db do* 2nd version submitted by Doug as a comment.
desc "Returns the current schema version"
task :version => :environment do
puts "Current version: " + ActiveRecord::Migrator.current_version.to_s
end
end
Comments:
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Maybe it's cause I'm on edge rails, but the return value from connection.execute(select) doesn't have a result method for me. This is the code that's working for me instead:
namespace :db do
desc "Returns the current schema version"
task :version => :environment do
connection = ActiveRecord::Base.connection
select = "select * from schema_info"
version = connection.execute(select).first["version"]
puts "Current version: #{version}"
end
end
(sorry don't know how to get whitespace formatting to work in blogger comments...)
namespace :db do
desc "Returns the current schema version"
task :version => :environment do
connection = ActiveRecord::Base.connection
select = "select * from schema_info"
version = connection.execute(select).first["version"]
puts "Current version: #{version}"
end
end
(sorry don't know how to get whitespace formatting to work in blogger comments...)
# posted by 
: 10:29 AM
: 10:29 AM
The last line of output from script/about lists the current schema revision. Setting RAILS_ENV allows you to query a particular environment's database.
Doug, thanks, I'll update the entry.
Jamie, I've never used script/about, thanks for pointing that out.
Jamie, I've never used script/about, thanks for pointing that out.
Just to be sure, I like to wrap that in a begin/rescue block
begin
puts 'current version is ' + ActiveRecord::Migrator.current_version}.to_s
rescue
puts 'database has not been migrated yet: ' + $!.to_s
end
begin
puts 'current version is ' + ActiveRecord::Migrator.current_version}.to_s
rescue
puts 'database has not been migrated yet: ' + $!.to_s
end
Thanks for this tip. I used it as a starting point so I can do:
#going backwards
rake db:rollback:4
# going forward
rake db:rollback:-3
It's on my blog if you're curious.
#going backwards
rake db:rollback:4
# going forward
rake db:rollback:-3
It's on my blog if you're curious.
And, much later, I turned this up while looking to do the same thing. I snagged the implementations offered by Doug and ncryptic and included them in a plugin called GenerallyUseful (with full credit to them and this post for the code).
Thanks for the post!
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Thanks for the post!
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