I have created an app using a badly named database, all alterations to important data in the database have been done in fixtures so that I can just drop the database, recreate it and then rake migrate the database tables and fill them with the initial data from the fixtures.
I would like to change the name of my database now, so I updated the database.yml file to reflect another database name. I created the database in mysql and then tried to run the migration and fixtures.
Running the migration with trace shows that it is running commands to create tables etc. However once I am finished I get errors in my application saying that the tables don't exist in the new database.
I go into mysql and check the database and it is completely empty. I have tried wiping everything and running the migrations a few times but nothing changes. Is there something I am missing?
I don't know what commands you used to do the migration, but to migrate a production database (which I infer from the tag, "production-environment"), you have to do:
RAILS_ENV=production rake db:migrate
If that's not the answer, then please provide the command you used to perform the migration, which database you expected to be affected, and the relevant bits of database.yml.
Related
I ran a simple rails migration on a large MySql2 db to add a column to a table:
class AddMiddleNameToPerson < ActiveRecord::Migration[5.0]
def change
add_column :person, :middle_name, :string
end
end
I was disconnected from the server running the rails app during the migration. I then reconnected and checked the migration status with bundle exec rake db:migrate:status, which showed it as down:
down 20170424182410 Add middle name to person
I assume it was still running in the background. So I left it for some time, and eventually using the rails console I verified that person.middle_name was accessible on objects. However, db:migrate:status still shows the migration as down, and if I try to run db:migrate again I get an error:
Mysql2::Error: Duplicate column name 'middle_name'
So it seems that the new column is in the database, and accessible through ActiveRecord, but rake db:migrate:status finds the migration as down and rake db:migrate attempts to re-run it, unsuccessfully.
If this is a production database (or other database with important data) then do not rake db:reset as that will drop the database and you'll lose everything; also don't db:migrate:down as that will drop the middle_name column and you'll lose whatever middle names you already have.
First get a backup of the database or at least the table you're working with.
Second, connect to the database with the mysql CLI tool and say describe people;. The information in your question suggests that you will see the middle_name column in there but it doesn't hurt to make sure you're connecting to the right database. If middle_name isn't there then you're almost certainly connecting to the wrong database somewhere, if it is there then you just have a migration issue to clean up.
You say that the database connection was dropped before the migration finished. Migrations work in this sequence:
Run the migration to update the database.
Record the migration's version number in the schema_migrations table.
Regenerate db/schema.rb or db/structure.sql.
If 1 completes but the connection is lost then 2 never happens so the migration will have run but Rails won't know it.
If no other environments need the migration then you can simply delete the migration and rake db:schema:dump or rake db:structure:dump to get a fresh schema.rb or structure.sql. Migrations are just temporary bits of code to get you from A to B so deleting them after they've been run everywhere is fine (and even recommended), all that matters long term is your database's structure (which is in db/schema.rb or db/structure.sql).
If other environments need to run the migration then you can manually patch the schema_migrations table; connect to the database with the mysql CLI tool and say insert into schema_migrations (version) values ('20170424182410');. Rails will now know that the migration was run and future rake db:migrate calls will be happy. Then you'd want to refresh your schema.rb (with rake db:schema:dump) or structure.sql (with rake db:structure:dump).
You probably have a db/schema.rb file for tracking your database's structure (including the version numbers of the migrations that have been run). If you do then you'd use rake db:schema:dump to regenerate it. If you have db/structure.sql then you'd use rake db:structure:dump.
I can't for the life of me figure out what's going on here, im not SUPER familiar with rails however:
I've modified my database.yml file to point to a new mysql test database instead of sqlite. When doing a RAILS_ENV=test db:drop db:create db:seed on dev it works fine.
HOWEVER it always fails on test, citing a table doesn't exist when being altered by one of the migrations. I tried the exact same .sql file loaded up on the database for dev as on the test db with no errors.
I was able to delete the test db and duplicate the dev database and it would work fine, but for some reason...with migrations it will not work on the test database (which is a freshly created database, but so is the dev technically since I drop and recreate it from scratch with a seed file everytime)
What could cause such a thing? Migrations working fine on a fresh DEV database (Mysql2) and not on a fresh TEST database (Also Mysql2)
for specifics the error is complaining about a table not being able to be altered, because it doesn't exist. (I confirm in SQL Pro that the table doesn't exist as well), but when migrations run on Dev database it works fine (even after being deleted and commands above (but just ran in RAILS_ENV=development) ran.
When you run db:create all it does is create a completely empty database, with no tables... you need to run either db:migrate or db:test:prepare in order for the actual tables (empty of data) to be added to the test database.
So your usual run should be: db:drop db:create db:migrate db:seed
HOWEVER... db:seed isn't going to work the way you want it to... every test completely empties the database of data every time (this is to prevent cross-contamination of test data), and db:seed is to add data to your development environment.
In the test environment you need to duplicate any seed-data into fixtures instead (or use appropriate factories).
I have situation here, I have a database in production environment, and now I have to add few columns in table and drop 1 table from the database. I ran all the migrations such as rails g migration AddDeskToHelper desk:string and similar for dropping a table.
But now I want to upload this new generated schema into existing database without deleting any data from the database.
I'm searching about it and did not find any accurate answer.
For example, here
it says that rake db:schema:load deletes all the data from Database in production environment.
Kindly help me in this case.
If you have created the migrations to add some cols in existing tables or delete some tables, the rake db:migrate RAILS_ENV=production command will perform an "ALTER table..." without destroying your data, except you are dropping a col or table with data content.
But it's always recommended to perform a database backup before altering your production database.
I know this one sounds kind of backwards! I've been working on a cloud-based case-management application, and was working on a support-ticketing feature. We have our development database (MySQL) that has all the same data as our production database (It's a very large app). Development is basically a "sandbox" environment, hence why the development db has all the same as the production db. This morning, I ran into a problem in my local development server for:
Migrations are pending; run 'bin/rake db:migrate RAILS_ENV=development' to resolve this issue.
Alright, did that, even though it didn't make any sense. It err'd out, because it was trying to create tables that already existed (I had already ran my migrations, the features were completed a day ago! And everything worked great).
The only thing that I did the moment before I got this message in my development server was uncomment an entirely-commented-out file to try and fix problems with TinyMCE (/config/tinymce.yml, text editor), followed by restarting my rails dev server. All this file was, was a bunch of defaults and plugins. When I saw the problem, I first commented them all back out. Still the same error. Proceeded with rake db: tasks.
Started looking for answers.. kept getting errors. Made a noob mistake, and ultimately did a
rake db:migrate:reset
which I knew would rebuild the schema at the cost of hosing the db. This failed.. But we do have the db in more than one place (since it's the same as production.) Also, just to try and bring all the tables back:
rake db:schema:load
....failed on one of the tables anyway with
ActiveRecord::StatementInvalid: Mysql2::Error: Specified key was too long; max key length is 767 bytes: CREATE UNIQUE INDEX `login` USING btree ON `users` (`login`, `intranet_id`)
..and all the tables are empty (as expected) that were successfully created. I'm by no means a database pro (I haven't dev'd very long). Am wondering, is there a way to copy the entire production database into the devel database? Tables, data, and all. Or any other suggestions? Really lost on this one.
You can use mysql_dump.
If you connect to the database everything is there - you just have to do a dump of the full database and then do the dump again into the production tables.
As you clearly see you can output from the database with ">" and you can import with the "<".
hi everybody i'm new to Ruby on Rails...
I created a Rails Application for that i created a database called 'cart' in MySQL database by using rake command. but unfortunately my database got crashed. right now there are no databases including older ones also deleted.
please help me, how can i get my all databases from MySQL s/w. is there any command to restore the crashed data.
Thanks
If you don't have backup it could be hard. You can remove database, create another and rake db:migrate but it will only create a structure for you and will not restore data.
You can try to reproduce your records from rails logs but it will be a lot of work
What do you mean by database crashed?