Unable to run ActiveRecord Migration

I added the gemfile:

gem 'activerecord-reputation-system', require: 'reputation_system'

to my Rails app in order to add upvote/downvote functionity to a model (I'm following Railscast #364). I installed the gem with no problems.

I entered 'rails g reputation_system' and rake db:migrate, but the rake was aborted:

Gem::LoadError: You have already activated rake 12.3.0, but your 
Gemfile requires rake 12.0.0. Prepending `bundle exec` to your command 
may solve this.

I tried it with 'bundle exec', but the rake was aborted again:

StandardError: An error has occurred, this and all later migrations 
canceled:

Directly inheriting from ActiveRecord::Migration is not supported. 
Please specify the Rails release the migration was written for:

I updated my gems to see if this was the trouble, but this made no difference.

I can't think of anything else I could do other than finding some way of removing rake 12.3.0 and installing 12.0.0, but this seems illogical.

Any help would be much appreciated, thanks :-)

---

In Rails 5 migrations require you to specify the Rails version you're using (the migration is specified for) at the top of your migration file, as the error states.

This looks like this:

class CreateYourModels < ActiveRecord::Migration[5.1]
 ...your migration code
end

Where the bit in brackets is the Rails version you're using.

Then try to run bundle exec rake db:migrate .

Additional explanation: https://blog.bigbinary.com/2016/03/01/migrations-are-versioned-in-rails-5.html

链接地址: http://www.djcxy.com/p/36000.html

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