I'm at the very beginning stages of learning rails using heroku as deployment tool. I ran into a bit of problem today, which is now fixed, but I was wondering if there's a proper/better way to do what I did.
My problem was as follows: I wrote a migration file that created a table with some indices (using add_index). The code would look like this:
class DeviseCreateUsers < ActiveRecord::Migration
def change
create_table(:users) do |t|
t.string :username
...
end
add_index :users, :username, :unique => true
end
def self.down
drop_table(:users)
remove_index :users, :username
end
end
heroku run rake db:migrate ran fine but heroku run rake db:rollback failed because (I assume) remove_index was trying to delete an index from a column that had already been erased.
So I then added a self.down method to my migration file (removing the indices before dropping the table). Afterwards, heroku run rake db:migrate didn't do anything, and heroku run rake db:rollback is stuck at the same error as before. Resetting the database or dropping the table didn't work either. I ended up removing the add_index lines in my migration before the rollback finally works.
... and unfortunately I no longer have any idea why db:rollback failed. The error message was 'index_users_on_username' on table 'users' does not exist', so my guess is that I did something stupid like modifying the database or modified the migration file before doing a rollback. Or could it be because I am mixing change and down method in the same migration file?
Anyway, my main question is, if a db:rollback fails, what then?
Some options in my head:
Fix the migration file until the rollback works
Fix the database manually until the rollback works
Fix the database manually and ignore the migration completely (dunno how to do this)
this)
???
Related
I've been trying to get the Paperclip gem working. The problem that I was initially running into was that pictures were getting uploaded but not displaying. I then messed around with the database by doing a rake db:rollback to try and fix the error. Now I can't rake db:migrate again because of this error
SQLite3::SQLException: duplicate column name: image_file_name: ALTER TABLE "posts" ADD "image_file_name" varchar
I've personally went into the migration folder and deleted the file to try and generate a migration again. I've been trying to do rails generate paperclip post image and it does create a migration file, but I'm unable to rake db:migrate.
Any suggestions?
Thanks!
Deleting a migration file doesn't really rollback the change it made in your database. Your best bet is to:
Don't delete the migration but comment out the content of the migration class, and run rake db:migrate,
Let's say I have this as my migration file
class AddEmailSentToNeeds < ActiveRecord::Migration
def change
add_column :needs, :email_sent, :boolean ,default: false
end
end
Just comment out the method but leave the class, so it would be:
class AddEmailSentToNeeds < ActiveRecord::Migration
# def change
# add_column :needs, :email_sent, :boolean ,default: false
# end
end
This is just a hacky way to tell rails to skip this migration.
OR
start from the start so go do, rake db:drop, rake db:create, and rake db:migrate
I want to remove a migration from my application.
I have a migration file 20141105030942_removedate_fromexpense.rb
the class file for the migrations is
class RemovedateFromexpense < ActiveRecord::Migration
def change
remove_column :expenses, :date, :date
end
end
When I give this command:
rake db:migrate:down VERSION=20141105030942
I get the following error:
== 20141105030942 RemovedateFromexpense: reverting ============================
-- add_column(:expenses, :date, :date)
rake aborted!
StandardError: An error has occurred, this migration was canceled:
SQLite3::SQLException: duplicate column name: date: ALTER TABLE "expenses" ADD "date" date/home/sumyvps/.rvm/gems/ruby-1.9.3-p545#railstutorial_rails_4_0/gems/sqlite3-1.3.8/lib/sqlite3/database.rb:91:in `initialize'
db:migrate:status for migration file is as below
up 20141105030942 Removedate fromexpense
Has anyone an idea why this is happening?
You do not need to specify the column type in your migration file. Just the name of the table and the column is enough to remove the column from the table.
Edit your migration file to:
class RemovedateFromexpense < ActiveRecord::Migration
def change
remove_column :expenses, :date
end
end
And then run:
rake db:migrate
This should do the work.
A common task is to rollback the last migration. For example, if you made a mistake in it and wish to correct it. Rather than tracking down the version number associated with the previous migration you can run:
rake db:rollback
This will rollback the latest migration, either by reverting the change method or by running the down method. If you need to undo several migrations you can provide a STEP parameter:
rake db:rollback STEP=3
will revert the last 3 migrations.
First Run:
rails generate migration RemoveDateFromExpense date:date
then rake db:migrate
Hope this help!
So I was trying to create a database index on the email column of a Users model, but I must be doing something wrong, since after I do the migration I go and check on the schema.rb file to see if the add_index method is included and nothing shows up. I am using postgresql, by the way. So here is what I did...
I created the migration
rails generate migration add_index_to_users_email
After that, I edited and saved the db/migrate/20140911192804_add_index_to_users_email.rb file with the following code for indexing:
class AddIndexToUsersEmail < ActiveRecord::Migration
def change
add_index :users, :email, unique: true
end
end
After that I ran on the console
bundle exec rake db:migrate
And when I went to check on the schema.rb file to see if the add_index method was included, I found that it wasnt there. Here is what my schema.rb looked like
ActiveRecord::Schema.define(version: 20140911192804) do
# These are extensions that must be enabled in order to support this database
enable_extension "plpgsql"
create_table "users", force: true do |t|
t.string "name"
t.string "email"
t.datetime "created_at"
t.datetime "updated_at"
end
end
I tried to run rake db:rollback to run again db:migrate and see if some "magic" occurred but I wasnt even able to rollback, getting this error message:
== AddIndexToUsersEmail: reverting ===========================================
-- remove_index(:users, {:unique=>true, :column=>:email})
←[1m←[35m (0.0ms)←[0m ROLLBACK
rake aborted!
An error has occurred, this and all later migrations canceled:
Index name 'index_users_on_email' on table 'users' does not existC:in `migrate'
Tasks: TOP => db:rollback
I'm pretty lost... something that i found interesting was that in the schema.rb file this line
ActiveRecord::Schema.define(version: 20140911192804) do
had the same timestamp as the migration file for the add_index db/migrate/20140911192804_add_index_to_users_email.rb
So there was some sort of update on the schema.rb file during the migration but not what I was expecting to occur.
I don't even know where to start :D so I hope someone a bit more experienced can give me a hint.
Thanks so much!
After hours of trial and error I could finally find a solution!
For some reason beyond my understanding, the migration didnt add the add_index method to my schema.rb, however, when I tried to rollback, it was looking for an index in the users table that didnt exist, so it kept aborting the rollback.
I assumed that the info about the index that it had to look for in the table was in the migration file. So I deleted the content of the migration file leaving it like this:
class AddIndexToUsersEmail < ActiveRecord::Migration
def change
end
end
I was finally able to rollback.
Then I typed again the content inside the AddIndexToUsersEmail migration file
class AddIndexToUsersEmail < ActiveRecord::Migration
def change
add_index :users, :email, unique: true
end
end
I ran again bundle exec rake db:migrate
and it worked! :D
Thanks a lot to everyone who took their time to read this issue!
I just had the same problem and found why !!!
You (we) used the migrate command before saving the migrate file !! So the migration was passed with nothing inside. Just a change method with no instructions.
And if after you try to rollback and the migration file have been saved since. The add_index instruction is in so it can't rollback.
I hope i am clear enough.
hi im currently learning rails, and following a tutorial. the instructions were to edit the migration file after i've created the app, then running rake db:migrate, then rake db:create.
i've edited the migration file to this:
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :username
t.string :email
t.string :encrypted_password
t.string :salt
t.timestamps
end
end
end
then when i've run 'rake db:migrate' i got an error
Mysql2::Error: Table 'users' already exists: CREATE TABLE `users` ...
after i'm supposed to run 'rake db:create', then im getting this
user_auth_development already exists
user_auth_test already exists
You run rake db:create once and only once, and you run it first. Then you run rake db:migrate every time you add/change a migration. You've either already run this migration, or you are pointing at a database that already exists and already contains a table named users. My guess is that you ran the migration once already, in which case you're probably good to go. If you want to nuke the DB and start over, do rake db:drop db:create db:migrate.
We can simply give, it will do all the rake task which is require for database creation and migration
rake db:setup
For Rails 5 and 6, the command is:
rails setup
This will "create the database, load the schema, and initialize it with the seed data" (docs).
For rails 6 & above, you can give this command to create a database, migrate all the migration files, and seed the data into the database:
rails db:prepare
From this morning, I am facing weird issues with Rails devise. Following is output of my ls and rake db version command.
hrishikesh#hrishikesh-ubuntu:~/git-public/personaldiary/db/migrate$ ls -1
20120110083934_devise_create_users.rb
20120110090514_create_posts.rb
20120110090845_add_user_id_to_post.rb
20120203035323_add_confirmable_to_devise.rb
20120203035323_add_confirmable_to_devise.rb~
20120203043601_add_lockable_to_devise.rb
20120203043601_add_lockable_to_devise.rb~
hrishikesh#hrishikesh-ubuntu:~/git-public/personaldiary/db/migrate$ rake db:version
(in /home/hrishikesh/git-public/personaldiary)
DEPRECATION WARNING: require "activerecord" is deprecated and will be removed in Rails 3. Use require "active_record" instead. (called from /usr/lib/ruby/vendor_ruby/activerecord.rb:2)
Current version: 20120203034555
hrishikesh#hrishikesh-ubuntu:~/git-public/personaldiary/db/migrate$
If I try to add any new migrations, rake db:migrate throws error that tells me that some column already exists, and fails.
My failing migration code is here:
class AddConfirmableToDevise < ActiveRecord::Migration
def change
change_table(:users) do |t|
t.confirmable
end
add_index :users, :confirmation_token, :unique => true
end
end
I specifically do not want to use up and down methods because of this
Please help.
After spending hours to find solution, I decided to give up and ran
rake db:migrate:reset
And it worked, only thing is my data was lost, which was not that big deal at this point.
Thank you everyone for attempting to solve this.