Ubuntu + Rmagick + Gem


If you run into trouble installing Rmagick on Ubuntu, it is most likely because you do not have the dev libraries installed that are needed by the rmagick Ruby Gem. Run the following commands in your terminal and everything should work fine.

sudo apt-get install graphicsmagick-libmagick-dev-compat
sudo apt-get install imagemagick
sudo apt-get install libmagickcore-dev
sudo apt-get install libmagickwand-dev
gem install rmagick

PostgreSQL + rake db:migrate

ActiveRecord::NoDatabaseError: FATAL: role “dev” does not exist

If you receive the error above when trying to run your Rails migrations against a newly installed instance of PostgreSQL on an Ubuntu development box, all you need to do is a new role to Postgres with the name ‘dev’. Once the role has been added and given the proper permissions, your migrations should run without issue.


Rails 4: Set Application-Wide Date/DateTime/Time Display Format

If you are like me, you want the all dates and times to display throughout your application using the same format. This can be accomplished through the following procedure.

Create a new Rails ‘Initializer’ file in your application’s ‘/config/initializers’ directory titled ‘date_format.rb’ and then paste into that file the following Ruby script. Simply uncomment the format you wish to use for each of the types Date, DateTime, and Time.

# Date
# —————————-
#Date::DATE_FORMATS[:default] = “%Y-%m-%d” # 2013-11-03
#Date::DATE_FORMATS[:default] = “%B %e, %Y” # November 3, 2013
#Date::DATE_FORMATS[:default] = “%e %b %Y” # 3 Nov 2013
#Date::DATE_FORMATS[:default] = “%Y%m%d” # 20131103
#Date::DATE_FORMATS[:default] = “%e %b” # 3 Nov

# DateTime
# —————————-
#DateTime::DATE_FORMATS[:default] = “%Y-%m-%d” # 2013-11-03 14:22:18
#DateTime::DATE_FORMATS[:default] = “%B %e, %Y” # November 3, 2013 14:22
#DateTime::DATE_FORMATS[:default] = “%e %b %Y” # Sun, 3 Nov 2013 14:22:18 -0700
#DateTime::DATE_FORMATS[:default] = “%Y%m%d” # 20131103142218
#DateTime::DATE_FORMATS[:default] = “%e %b” # 3 Nov 14:22

# Time
# —————————-
#Time::DATE_FORMATS[:default] = “%Y-%m-%d %H:%M:%S” # 2013-11-03 14:22:18
#Time::DATE_FORMATS[:default] = “%B %d, %Y %H:%M” # November 3, 2013 14:22
#Time::DATE_FORMATS[:default] = “%a, %d %b %Y %H:%M:%S %z” # Sun, 3 Nov 2013 14:22:18 -0700
#Time::DATE_FORMATS[:default] = “%d %b %H:%M” # 3 Nov 14:22
#Time::DATE_FORMATS[:default] = “%Y%m%d%H%M%S” # 20131103142218
#Time::DATE_FORMATS[:default] = “%H:%M” # 14:22

Rails 4: gem install pg (when using the Postgresql App on OS X)

If you are getting a build error from Gem when trying to install the PostgreSQL gem called ‘pg’ and you are using the PostgreSQL App instead of installing PostgreSQL via Brew or some other method, it is because Gem cannot find the PostgreSQL config in the standard locations. To correct this you need to provide Gem with the path to the config file stored within the PostgreSQL App’s internal folder structure.

This can be done as follows:

gem install pg -- --with-pg-config=/Applications/Postgres.app/Contents/Versions/9.4/bin/pg_config

<update: for latest versions of Postgres.app>

gem install pg -- --with-pg-config=/Applications/Postgres.app/Contents/Versions/latest/bin/pg_config

Another way to accomplish this is:

export CONFIGURE_ARGS=”with-pg-include=/Applications/Postgres.app/Contents/Versions/9.4/include/”
gem install pg

Note: the latest version of the PostgreSQL App, at the time of this writing was 9.4, your version may be different. Make sure you change the 9.4 in the config path in the command above to the one you are using or it will not work. You can verify the path by opening Finder, going to the Applications folder, locating Postgres.app, right clicking and selecting ‘show package contents’. This will open up the app’s folder structure in Finder.

Rails3: ActiveRecord accepts_nested_attributes_for not working (can’tmass-assign protected attributes)

In one of my applications I ran into a situation where I needed to have a single form handle a model as well as several of its associations. Meaning I needed the form to handle CRUD events for the model plus the associated models auto-magically. With that objective I remembered a RailsCast.com video cast explaining how to use the ActiveRecord ‘accepts_nested_attributes_for’ method.

So I jumped on the web and coded along while I watched the cast. But for some strange reason the code from the cast just wouldn’t work. When I saved the survey no associated questions were saved to the database despite the fact that the survey came back as successfully saved. So I triple checked that I had it all correct. Once I was satisfied that it was correct I started digging deeper when I noticed in the passenger logs in my console the following error message hidden nicely within the POST printout and the SQL statements.


WARNING: Can’t mass-assign protected attributes: questions_attributes


That made me think, Rails has started doing a much better job protecting our applications from Mass-Assignment attacks by requiring us to explicitly set the model attributes which are accessible and can be directly updated via a form post. I then reviewed the POST parameters to see what was being returned by the form (see below).


Parameters: {“utf8″=>”✓”, “authenticity_token”=>”8XugXn/UwE+m4m2BR2pfTy7oVfUI+jKnPYaSNwKiD1s=”, “survey”=>{“name”=>”test”, “questions_attributes”=>{“0″=>{“content”=>”question1”}, “1”=>{“content”=>”question2”}, “2”=>{“content”=>”question3”}}}, “commit”=>”Submit”}


Within the parameter list for the survey sent back by the form I noticed the addition of the ‘questions_attributes’ hash which holds each question with its associated hash of fields and values. Being that the ‘questions_attribute’ is a newly introduced attribute to a survey via the ‘accepts_nested_attributes_for’ method it now becomes filtered by Rails as NOT mass-assignable.

Once I added ‘questions_attributes’ to the survey model’s ‘attr_accessible’ method and retested it worked without an issue. Hope this helps those who might be stuck trying to get nested forms to work.

Rails: Flash Message Partial (self-hiding)

(Wed. June 8th 2o11, 11:00 pm)

For self -hiding Ruby on Rails 3 flash messages you can use the following in a partial which can be included within application layouts. (requires you are using jQuery)

<br /><div id="flash-banner"><br /><br /> "flash " + key.to_s, :id =&gt; key.to_s + "-message" %&gt;<br /> "text/javascript" do %&gt;<br />$('#').css('display', 'none');<br />$('#').slideDown().delay(1000).slideUp();<br /><br /><br /></div><br />