Recent notes

Using strings as association names

Beware, that using strings as association names, when giving Hash to :include will render errors:

The error occurred while evaluating nil.name

So, :include => [‘assoc1’, ‘assoc2’ ] will work, and :include => [ {‘assoc1’ => ‘assoc3’}, ‘assoc2’] won’t. Use symbols:

Proper form

:include => [ {:assoc1 => :assoc3}, ‘assoc2’]

Real HTML_ESCAPE VALUE

Real value:

HTML_ESCAPE = { '&' => '&',  '>' => '>',   '<' => '<', '"' => '"' }

Format not coming out properly?

Date, Time and DateTime may have different formats defined.

If you do:

@user.created_at.to_formatted_s(:long_ordinal)

You will get (or something):

April 16th, 2009 22:03 

But if you do:

@user.created_at.to_date.to_formatted_s(:long_ordinal)

You will get:

April 16th, 2009

So, be sure you know which one you are working with.

To throw an exception, use Kernel#raise

Other languages use the term throw for raising exceptions, but Ruby has a specific raise call for that.

Do not forget to add indexes

Don’t forget to add indexes to HATM table:

add_index :developers_projects, [:developer_id, :project_id]

Merges with inherited values from super class

http://www.spacevatican.org/2008/8/19/fun-with-class-variables

“When you set a class_inheritable_array or a class_inheritable_hash you are actually concatenating (or merging) with the value inherited from the super class.”

Code example

class Base
  class_inheritable_hash :attrs
  self.attrs = {:name => 'Fred'}
end

class Derived < Base
  self.attrs = {:export => 'Pain'}
end

Derived.attrs #=> {:name => 'Fred', :export => 'Pain'}

strip_tags method not functioning in controllers, models, or libs

It comes up with an error about white_list_sanitizer undefined in the class you’re using it in. To get around this, use:

ActionController::Base.helpers.strip_tags('string')

To shorten this, add something like this in an initializer:

class String
  def strip_tags
    ActionController::Base.helpers.strip_tags(self)
  end
end

then call it with:

'string'.strip_tags

strip_links method not functioning in controllers, models, or libs

It comes up with an error about white_list_sanitizer undefined in the class you’re using it in. To get around this, use:

ActionController::Base.helpers.strip_links('string')

To shorten this, add something like this in an initializer:

class String
  def strip_links
    ActionController::Base.helpers.strip_links(self)
  end
end

then call it with:

'string'.strip_links

sanitize method not functioning in controllers, models, or libs

It comes up with an error about white_list_sanitizer undefined in the class you’re using it in. To get around this, use:

ActionController::Base.helpers.sanitize('string')

To shorten this, add something like this in an initializer:

class String
  def sanitize
    ActionController::Base.helpers.sanitize(self)
  end
end

then call it with:

'string'.sanitize

Corrected link to ActiveRecord's "new_record?" method

rafaelrosafu, the correct tink to ActiveRecord’s “new_record?” method is:

"http://apidock.com/rails/ActiveRecord/Base/new_record%3F"

Cycle with first and last

I needed a cycle that was also aware of the first and last items in the collection. This is adapted from a snippet I found while Googling:

def cycle_with_first_last(object, collection, options = { })
  addition = ""
  addition += " #{options[:first]}" if object == collection.first
  addition += " #{options[:last]}"if object == collection.last
  cycle(options[:odd], options[:even]) + addition
end

Just put that in your helpers…

Extracting the First Element

To extract the first element from an Array, use shift:

array = [ 1, 2, 3 ]           # => [ 1, 2, 3 ]
array.first                   # => 1
array                         # => [ 1, 2, 3 ]
array.shift                   # => 1
array                         # => [ 2, 3 ]

Extracting the Last Element

To remove the last element from the Array, use pop:

array = [ 1, 2, 3 ]           # => [ 1, 2, 3 ]
array.last                    # => 3
array                         # => [ 1, 2, 3 ]
array.pop                     # => 3
array                         # => [ 1, 2 ]

Parameters for Hash#inject

When running inject on a Hash, the hash is first converted to an array before being passed through.

The typical Enumerable#inject approach would be to simply capture the value:

array.inject(...) do |c, v|
end

In the case of a Hash, v is actually a key/value pair Array. That is the key is v.first and the value is v.last, however using the pair this way is awkward and can lead to confusion.

Better to simply expand the parameters in the block definition:

hash.inject(...) do |c, (k, v)|
end

Where c is the traditional carry variable and k/v represent key and value respectively.

Example

This function can be used to pass the ID of selected item, for example:

# with select or collection_select helpers:
{ :onchange => remote_function(:url => { :action => 'do_smth' }, :with => "'id=' + $('the_id').value") }

# and grab ID in controller action as usually: 
YourModel.find(params[:id])

Various use cases

Example

user = User.new
user.name = 'Akhil Bansal'
user.save

user =  User.new(:name => 'Akhil')
user.save

User.new do |u|
  u.name = 'Akhil'
  u.save
end

Known unknowns

In case it isn’t obvious - this is what you use when you’re fleshing out all the tests that you haven’t written yet. eg if you have a set of twenty tests for a complex piece of functionality, and just want to write out the “should” declarations (or equivalent), so you don’t forget all the corner cases… then fill out the tests themselves. Putting an assert_fail makes sure you notice if you forget to come back and fill in the body of a test.

Testing HTTP Digest authentication

Testing HTTP Digest authentication is a bit tricky. I wrote a post describing how to accomplish it.

http://lightyearsoftware.com/blog/2009/04/testing-http-digest-authentication-in-rails/

Note also that Digest auth is broken for REST actions using PUT or DELETE. There is an open Lighthouse ticket for this, #2490:

rails.lighthouseapp.com/projects/8994/tickets/2490-http-digest-auth-uses-wrong-request-method-for-put-delete

Using global $! to address exception

@noxyu3m: Your code is actually syntactically wrong. The global is called $!

Your code should have been:

def create
  @model = Model.new(params[:model)
  @model.save!
rescue
  logger.error($!.to_s)
end

Although I would prefer

def create
  @model = Model.new(params[:model)
  @model.save!
rescue ActiveRecord::RecordInvalid
  logger.error($!.to_s)
end

to only catch expected exceptions, just like the documentation proposed.

Inflector moved to ActiveSupport::Inflector

Inflector moved to ActiveSupport::Inflector

Re: Force initial value

An alternative to @eric_programmer’s would be to extract it entirely from the controller logic…

class Person
  def sender
    self[:sender] || 'contact@host.com'
  end
end

There are a ton of ways to do it, but making this a business logic decision will let you get the same logic from any possible implementation angle. Scripts, web service, etc.

To find a tag with an id or class

assert_select ‘td.highlight’, { :count => 2 }

finds 2 td tags with the highlight class.

assert_select ‘div#special’

finds div with id=special

Takes attribute as a symbol

Attribute must be passed as a symbol:

User.toggle(:funny)

not

User.toggle(funny)

Deprecation warning for old-style options

You will get a warning if you don’t define your separators as a hash:

DEPRECATION WARNING: number_with_delimiter takes an option hash instead of separate delimiter and precision arguments

So while you can still use that style, it’s not without a scolding.

Outside of app code

How do I call this from script/console?

Define handlers in order of most generic to most specific

The later the definition of the rescue handler, the higher the priority:

rescue_from Exception, :with => :error_generic
rescue_from Exception::ComputerOnFire, :with => :panic

Declaring the Exception catch-all handler last would have the side-effect of precluding any other handlers from running.

This is what is meant by being “searched…from bottom to top”.

Method has moved to ActionController::Rescue::ClassMethods module

This method has simply moved, still works the same way in 2.3+

New location: ActiveSupport::Rescuable::ClassMethods#rescue_from

Like select_values for multiple values

The names are somewhat confused:

Model.connection.select_values("SELECT id,name FROM users") => ["1","2","3"]
Model.connection.select_rows("SELECT id,name FROM users") => [["1","amy"],["2","bob"],["3","cam"]]

select_values returns Strings for MySQL

This method will return all values as strings from MySQL. It is easy to convert if required, for example, to integers:

select_values("SELECT id FROM companies LIMIT 3") => ['1','2','3']
select_values("SELECT id FROM companies LIMIT 3").collect(&:to_i) => [1,2,3]

use create table :force => true

if you want to drop a table before creating one in a migration, use the :force => true option of the create_table method