EzDevInfo.com

Rails 3, how to roll back a Migration file?

I have the following Rails 3 migration file db\migrate\20100905201547_create_blocks.rb

How can I specifically roll back that migration file?

How do I reverse a 'rails generate' ?

i.e. delete all the files it created and roll back any changes made? Not necessarily to the db, but more to the config files.

E.g. automatically deleting all the resource mappings for the model/controller deleted in the routes.rb file and everywhere else that changes might have been made?

Thanks.

Rails DB Migration - How To Drop a Table?

I added a table that I thought I was going to need, but now no longer plan on using it. How should I remove that table?

I've already ran migrations, so the table is in my database. I figure rails generate migration should be able to handle this, but I haven't figured out how yet.

I've tried rails generate migration drop_tablename, but that just generated an empty migration.

What is the "official" way to drop a table in Rails?

How to empty DB in heroku

Im working on a RoR3 webapp on heroku. How do I empty the database?

Change a column type from Date to DateTime during ROR migration

I need to change my column type from date to datetime for an app I am making. I don't care about the data as its still being developed.

How can I do this?

How can I rename a database column in a Rails migration?

I wrongly named a column hased_password instead of hashed_password.

How can update database scheme with using migration to rename this column?

Can't find the 'libpq-fe.h header when trying to install pg gem

I am using rails 3.1 pre version. I like to use PostgreSQL but the problem is installing the pg gem. It gives me the following error:

demonchand@system-001:~/exercise/personal/pro$ gem install pg
Building native extensions.  This could take a while...
ERROR:  Error installing pg:
    ERROR: Failed to build gem native extension.

        /home/demonchand/.rvm/rubies/ruby-1.9.2-p0/bin/ruby extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/home/demonchand/.rvm/rubies/ruby-1.9.2-p0/bin/ruby
    --with-pg
    --without-pg
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config


Gem files will remain installed in /home/demonchand/.rvm/gems/ruby-1.9.2-p0/gems/pg-0.11.0 for inspection.
Results logged to /home/demonchand/.rvm/gems/ruby-1.9.2-p0/gems/pg-0.11.0/ext/gem_make.out

Can anyone tell me how do I solve this problem?

Repairing Postgresql after upgrading to OSX 10.7 Lion

I recently upgraded to OSX 10.7, at which point my rails installation completely borked when trying to connect to the psql server. When I do it from the command line using

psql -U postgres

it works totally fine, but when I try to run the rails server or console with the same username and password, I get this error

...activerecord-3.0.9/lib/active_record/connection_adapters/postgresql_adapter.rb:950:in `initialize': could not connect to server: Permission denied (PGError) 
Is the server running locally and accepting
    connections on Unix domain socket "/var/pgsql_socket/.s.PGSQL.5432"?

Any ideas what might be going on would be super helpful! Thanks!

Use rvmrc or ruby-version file to set a project gemset with RVM?

I use RVM, the Ruby Version Manager to specify a Ruby version and a set of gems for each of my Rails projects.

I have a .rvmrc file to automatically select a Ruby version and gemset whenever I cd into a project directory.

After installing RVM 1.19.0, I get a message

You are using .rvmrc, it requires trusting, it is slower and it is not compatible with other ruby managers, you can switch to .ruby-version using rvm rvmrc to [.]ruby-version or ignore this warnings with rvm rvmrc warning ignore /Users/userName/code/railsapps/rails-prelaunch-signup/.rvmrc, .rvmrc will continue to be the default project file in RVM 1 and RVM 2, to ignore the warning for all files run rvm rvmrc warning ignore all.rvmrcs.

Should I continue using my .rvmrc file or should I switch to a .ruby-version file? Which is optimal? What are the ramifications?

Rails - Could not find a JavaScript runtime?

I created a new Rails project using rails 3.1.0.rc4 on my local machine but when I try to start the server I get: Could not find a JavaScript runtime. See here for a list of available runtimes. (ExecJS::RuntimeUnavailable)

Note: This is not about Heroku.

How can I specify a local gem in my Gemfile?

I'd like Bundler to load a local gem. Is there an option for that? Or do I have to move the gem folder into the .bundle directory?

Rails update_attributes without save?

Is there an alternative to update_attributes that does not save the record?

So I could do something like:

@car = Car.new(:make => 'GMC')
#other processing
@car.update_attributes(:model => 'Sierra', :year => "2012", :looks => "Super Sexy, wanna make love to it")
#other processing
@car.save

BTW, I know I can @car.model = 'Sierra', but I want to update them all on one line.

How to run `rails generate scaffold` when the model already exists?

I'm new to Rails so my current project is in a weird state.

One of the first things I generated was a "Movie" model. I then started defining it in more detail, added a few methods, etc.

I now realize I should have generated it with rails generate scaffold to hook up things like the routing, views, controller, etc.

I tried to generate the scaffolding but I got an error saying a migration file with the same name already exists.

What's the best way for me to create scaffolding for my "Movie" now? (using rails 3)

Best way to load module/class from lib folder in Rails 3?

Since the latest Rails 3 release is not auto-loading modules and classes from lib anymore, what would be the best way to load them?

From github:

A few changes were done in this commit:

Do not autoload code in *lib* for applications (now you need to explicitly 
require them). This makes an application behave closer to an engine 
(code in lib is still autoloaded for plugins);

How to remove a key from Hash and get the remaining hash in Ruby/Rails?

To add a new pair to Hash I do:

{:a => 1, :b => 2}.merge!({:c => 3})   # => {:a=>1, :b=>2, :c=>3}

Is there a similar way to delete a key from Hash ?

This works:

{:a => 1, :b => 2}.reject!{ |k| k == :a }   # => {:b=>2}

but I would expect to have something like:

{:a => 1, :b => 2}.delete!(:a)   # => {:b=>2}

It is important that the returning value will be the remaining hash, so I could do things like:

foo(my_hash.reject!{ |k| k == my_key }

in one line.