Truncate table(s) with rails console

问题:

I have this testingdatabase which, by now, is stuffed with junk. Now I've done a few Table.destroy_all commands in the rails console which deletes all records and dependencies which is awesome. However; I'd like to truncate everything so the ID's etc. start at 1 again. Is there any way in Rails 3?

回答1:

The accepted answer only works if you need to recreate the whole database.
To drop a single table (with the callbacks) and to get the IDs to start from 1:

Model.destroy_all # Only necessary if you want to trigger callbacks.
ActiveRecord::Base.connection.execute("TRUNCATE #{table_name} RESTART IDENTITY")

If you are using Sqlite, it does not support truncate so do the following:

Model.destroy_all # Only necessary if you want to trigger callbacks.
ActiveRecord::Base.connection.execute("Delete from #{table_name}")
ActiveRecord::Base.connection.execute("DELETE FROM SQLITE_SEQUENCE WHERE name='#{table_name}'")

回答2:

Model.connection.truncate(Model.table_name)

回答3:

This worked for me - ActiveRecord::Base.connection.execute("TRUNCATE table_name")

回答4:

Simply rebuild the database on the next test run (this will happen automatically after dropping it).

rake db:drop RAILS_ENV=test

回答5:

You could also do rake db:rollback STEP=3 RAILS_ENV=test

where 3 represents the number of migrations that you have in db/migrate. In example: If I have in

db/migrate
20140121065542_create_users.rb
20140121065710_create_profiles.rb
20140121065757_create_articles.rb
20140121065900_create_comments.rb
20140121065929_create_categories.rb

So I have 5 migrations in total to remove. If I do rake db:rollback STEP=5 RAILS_ENV=test all the tables will be drop from my TEST database and if I remove RAILS_ENV=test than all the ENVIRONNMENT (production, test, development) tables will be delete and it cleans also db/shema.rb file from it's migration datas.

回答6:

rake db:reset will perform rake db:drop db:setup. In other words, drop the database and setup the database again.

Source

回答7:

Assuming you're using MySQL or Postgre and not SQlite3 (which doesn't support TRUNCATE), you could do the following:

MyModel.connection_pool.with_connection { |c| c.truncate(MyModel.table_name) }

Note that this would not invoke ActiveRecord callbacks.

回答8:

(A bit late to the party, I know)

Asking to do this in the console:

2.1.2 :001 > Post.all.each do |post|
2.1.2 :002 >   post.destroy!
2.1.2 :003 > end

Works as well...

This essentially loops through all of the posts and destroys them. It does not change your auto increment value though...

Same logic should work for Rails 3 as well (though I am using Rails 4)