I'm a little confused by the intended use of the default Rails Rake tasks, and would like advice on whether I should be using db:reset or writing a custom Rake task. Nothing clever, just daily housekeeping, and I may well be missing an obvious doc as I'm new to Rails.
My problem: I want to throw away my database and run from a completely clean setup, in order that I can be sure the database contains known data only. This is useful for demo prep, for debugging, and for making sure Jenkins is comparing like-with-like in tests.
Currently, I'm writing this:
bin/rake db:drop:all db:create:all db:migrate db:seed db:test:prepare
This is a lot to type, but leaves seed data only in both dev and test databases. I am unsure how this differs from db:reset, which would be more convenient to type.
Should I use db:reset or write a custom db:from_scratch task?
You should be using:
rake db:reset
This will drop the database, recreate it and load the current schema into it.
For a full list of rake db tasks:
rake --describe db
If your requirements change then it would be better to write a custom rake task, where you can apply your own customisation.
If you're not sure what a rake task does, then I would suggest not using it. In this case, you're probably ok, however db:reset is not the equivalent to what you are doing above. db:reset recreates the database from scheme.rb, this may be different as you could have written migrations that have not yet been run.
I would suggest that you use a custom rake task, you can then modify it to fit your exact purposes, especially if you want to perform other tasks as well (for example tagging in git)
What you are trying to achieve in your the tasks you are running through rake is setting both the test and the development databases. rake db:reset will just do it for your current environment db according to the schema.rb and then load the seeds data into the db. The schema.rb in general is never edited, its for a know-only/refer-only purpose, however some people do tend have different schema.rb which might create a problem :(. What sounds better to me is if you need to set both your development and test database, then run your migrations for the dev environment and use the schema.rb to create the test environment db. I would definitely suggest you to get a second opinion from some Rails guru though to find out a real perfect way to achieve what you want.
rake db:reset
This will drop the database, recreate it and load the current schema into it.
rake db:reset will run rake db:seed
Example :
if you have seed file that you wrote after you ran your migration , it will run that too.
Related
I've been having a problem which doesn't seem uncommon (I've read a lot of stack overflow pages in the last 2 days) but every solution I've read hasn't worked for me.
I've been following this video tutorial
At 6:42 the tutor shows the tables in postgresql and mine don't show up.
When I try rake db:migrate the files migrate no problem. rake doesn't throw up any errors, the relevant .rb files are created in the models folder, my schema.rb looks right. It seems postgresql just isn't reading my schema file.
My problem sounds identical to
rake db:migrate doesn't seem to work in production
However typing rake db:migrate RAILS_ENV=production doesn't work. (I've tried this a few times after other rake commands like rake db:rollback STEP=3 in the past few days because I was paranoid it was the solution, this person on ruby forum, has the same problem and is offered the same answer).
This is my first attempt at programming anything and I'm loving the tutorial (and the learning curve this problem has turned out to be) Asking here is pretty much my last resort because I've tried everything I can understand online as a possible solution so please help me! Thanks a lot in advance
There is quite a bit of confusion going on here:
Migrations
Migrations are a convenient way to alter your database schema over
time in a consistent and easy way. They use a Ruby DSL so that you
don't have to write SQL by hand, allowing your schema and changes to
be database independent.
Postgres does not read your schema file or migrations - rather migrations run SQL queries against your database. In this case a CREATE TABLE ... query will be run when the migration is run.
Migrations are basically a more maintainable and sane way of doing what was classically done by opening a DB console and running SQL queries.
config/schema.rb is not actually used by the database or ActiveRecord - rather its created when you run migrations as a snapshot of what the database schema should look like. Its just a developer convenience. ActiveRecord gets its mappings by querying the database schema.
Migrations and generators
Migrations do not create model files either - those are generators such as:
rails g model Dude abides:boolean
Which creates a CreateDudes migration and a model at app/models/dude.rb.
In fact migrations are just concerned about altering the DB schema and don't care if the model file exists or not - the models is not actually used until you query the database for records.
ENV vars
RAILS_ENV=production sets a environmental variable.
rake db:migrate RAILS_ENV=test
Is the documented way to run a migration in a different environment. Some obscure shells require the ENV var to prefix the command.
However - if you are running a production server you should set the RAILS_ENV env var permanently - not on invocation! This prevents embarrassing misstakes when someone expected you to have configured the server properly and just ran rails s when restarting the server. See the documentation for your server OS on how to set env vars.
If you are still running the migration and do not see the expected results you most likely have not configured config/database.yml properly - the migrations are running. But not against the database you would expect.
http://guides.rubyonrails.org/active_record_migrations.html
I'm beginner in Ruby on Rails. I dropped my table. But I have the files in the db/migrate folder. How can I get back my table from those migrate files?
The ideal way to do this, is using
rake db:setup
This will recreate the database and load the schema into the development database. With every migration rails keeps the current state of the database in schema.rb (or structure.sql), and it uses those to efficiently recreate the last state.
If you have pending migrations, you will have to do rake db:migrate, but this will take more time, since it will redo every step as before.
Also note in some cases it is not possible to run the migrations from the start again, and imho that is not the intention of the migrations.
Run rake db:migrate to get it back.
According to this question, you should be able to do the following:
rake db:create #-> creates DB based on the schema file
rake db:migrate #-> populates the db with the various changes in the migrations
If you follow these steps, with nathanvda's advice, you should be able to solve the issue you're seeing!
I'm working on deploying my first Rails application right now, and somewhere along the way, I botched a migration. When I try to push my application to the production server and run rake db:migrate, it fails somewhere with an error.
Now, I am way too lazy to work through my migrations individually to find out what went wrong, so I'm trying to avoid doing that. Given that my current development database works just fine, is there a way to "flatten" the current schema into a single, comprehensive migration?
I understand that this is sloppy, and I understand that I likely did a dumb thing to break the migration chain in the first place. (I probably edited the database schema directly somewhere, which I now understand is a no-no.) This is a pretty small project though, and I'm essentially the only developer involved, so I'm comfortable sweeping this issue under the rug if possible.
Is there a way to do that?
Thanks for lending your expertise.
This is what the db/schema.rb file is for. If you've only got structural changes in your migrations you will be able to run rake db:schema:load rather than running rake db:migrate to get the absolute structure for your tables.
If you edited the schema directly you will need to run:
rake db:schema:dump
This will take whatever is in the database and create a schema.rb file. Then you can run rake db:schema:load anytime you want. However it will mean that your migrations are still bad. You could delete all of them and recreate them from the schema.rb file.
Currently i'm using this:
edit creation migrate
rake db:drop
rake db:migrate
rake db:seed
but I often can see making migrations for every added or edited column and so on.
I think my way is better because its much cleaner and faster to migrate to production environment (one sql for one table). Are there any disadvantages of using my method?
What do you think?
EDIT:
Just to be clear: i'm talking about stage BEFORE any production, when I'm coding on my own PC and even don't think about production yet.
Incremental migrations are definitely needed in production, where you can't get away with dropping entire databases. Using them in development as well helps you to ensure that they're correct.
Understand what you are trying to achieve here but how you're going about it is very wrong.
Your development environment should be as close to your production environment as possible.
Could run into allsorts of problems.
What happens when you need to replicate the production environment on dev?
What happens when you "forget" to add/take-away something on prod that you have done using a migration that is lost?
For dev, maybe a better command would be rake db:rolback, which rolls back the previous migration if you need to edit it for typo or something.
Just out of curosity - why not use rake db:reset instead of the three individual rake tasks?
Is there a rake command in Rails 3 to clone my development database data? I noticed rake db:test:prepare and rake db:test:clone are mentioned throughout various blogs, but running them seems to do nothing. Furthermore, rake -T shows no db:test cases. I've resorted to loading a sql dump for now, but it would be great if I could just clone my existing development data for up-to-date testing.
EDIT --
I desire to test on a database since I am dealing with legacy data that I run through model filters when accessed. Factories won't work for me in this context, since data passed through create is defined as a different schema than that of the legacy data.
rake db:test:prepare is still there even though it doesn't show up in rake -Tdb. I guess the Rails team decided to de-clutter the rake -T output?
I would suggest you not clone your development database but rather rely on factories to give you predictable data you can craft for your exact test cases. Sooner or later, relying on having reliable test data in a database you can access will break your tests. It will also break the tests of anyone else who works on the project. And changes/additions to the data will not propagate to other developers as would your carefully constructed factories.
Look over Machinist, FixJour, FactoryGirl and the lot. They really solve the test data problem well and you check them into version control so the rest of your team has access to them.