Notes posted to Ruby on Rails

(Another) Pluralize Without Showing the Count

Thought it would be best to take the source code from pluralize and just remove the count from the output.

Create this helper method in application_helper.rb

# Pluralize without showing the count.
def simple_pluralize count, singular, plural=nil
  ((count == 1 || count =~ /^1(\.0+)?$/) ? singular : (plural || singular.pluralize))
end

This allows you to pass in in the plural word to use as well.

Does not work for has_one associations

If you are using this to validate that a has_one association has been made with another object this will not work, as the test used in the AssociatedValidator #validates_each method tests for nil and then ignores this object.

To test for association with a has_one association you can use the following code:

validate do
  [:teacher, :book].each do |attr|
    errors.add(attr, "is required") if self.send(attr).nil?
  end
end

Options

See: http://apidock.com/rails/ActionView/Helpers/FormTagHelper/number_field_tag

the correct return value of html_escape in example above

the correct return is:

# => is a > 0 & a < 10?

The :path option

The path option will actually set the path and not the prefix I have found in Rails 3.0.5.

Example

resources :my_reports, :path => 'my-reports'

All actions for this resource will now be at /my-reports.

Security issue

One thing to note about the code above is that it could have a security issue. If the user changes his/her password, the authentication token should expire. Hence, in a production scenario you should put in the password salt or something to allow the token to become invalidated.

More AREL compliant style is also possible

Code example

Person.where(:name => 'David').exists?

Look at mail gem

If you’re looking for mailer methods like “deliver” for rails 3 or later, you should look into “mail” gem: http://github.com/mikel/mail

HTML5 support

To support multiple file selection simply pass :multiple => true in the options hash:

file_field_tag 'file', :accept => 'image/jpeg', :multiple => true

Speccing read_only requirements

To test if an attribute is defined readonly:

class MyModel < ActiveRecord::Base
  attr_readonly :important_type_thingie
end

#RSpec
describe MyModel do
 its('class.readonly_attributes') { should include "important_type_thingie" }

 it "should not update the thingie" do
   m = create :my_model, :important_type_thingie => 'foo'
   m.update_attributes :important_type_thingie => 'bar'
   m.reload.important_type_thingie.should eql 'foo'
 end
end

Examples out of order

The second and third examples should exchange places to fit with their explanations.

Rescuing DeleteRestrictionError via flash message

Model

class ShareType < ActiveRecord::Base
  has_many :shares, :dependent => :restrict
end

Controller

class ShareTypesController < ApplicationController
  def destroy
    begin
      @share_type.destroy
      flash[:success] = "successfully destroyed." 
    rescue ActiveRecord::DeleteRestrictionError => e
      @share_type.errors.add(:base, e)
      flash[:error] = "#{e}"
    ensure
      redirect_to share_types_url
    end
  end
end

default value for :use_full_path

FYI, It in Rails 2.1.1 the default value for :use_full_path has changed from true to false.

This will show up as an error stating “No such file or directory”

Basic usage

Basic usage example:

class User < ActiveRecord::Base
   #...
   skip_callback :create, :after, :send_welcome_email
   #...
end

sure, but what types are there to chose from?

the ‘symbol’ parameter is not something specific like ‘:after_save’, but rather ‘:save’

I suppose ‘:update’ works as well.

includes request parameters

fullpath includes request parameters in the result

Multiple update, on query ?

Person.update(people.keys, people.values)

Will this request issue one or multiple queries to update the table data (as in http://stackoverflow.com/questions/3432/multiple-updates-in-mysql#3466 )

The answer is: it will do TWO queries per updated row. One select and one update.

No way to use custom message

In what appears to be a bug, there appears to be no way to use a custom error message when using this validator.

Available Options and their meaning

key

Name of the cookie for the session

secure

If true, session cookie is sent only to https hosts. This protects your app from session hijacking ( remember firesheep? )

expire_after

Self explanatory (e.g. 60.minutes)

domain

To which domain the cookie declares to be for

This very good post shows how to use :domain and :key to implement single-sign-on: http://itshouldbeuseful.wordpress.com/2011/02/02/rails-authlogic-and-single-sign-on/

Common Validator options

Most validators will support all of the following common options: (Through ActiveModel::Errors::CALLBACK_OPTIONS (http://apidock.com/rails/ActiveModel/Errors))

• :if

• :unless

• :allow_blank

• :allow_nil

Another way to use

<%=

link_to_unless_current("Profile", profile_path) 

%> also works (instead of pointing to controller/action)

Default values

For common attributes in several models, you can set a default human name like this:

de.yml

de:
  attributes:
    bez: Bezeichnung
    abk: Abkürzung

Updating nested attributes of one-to-one associations

As the documentation implicitly mentions, when updating nested attributes of a one-to-one relationship, you need to pass the ID of the nested attribute itself, otherwise a new record will be created.

This works fine:

params = { :member => { :avatar_attributes => { :id => '2', :icon => 'sad' } } }

However, the following line will build and save a new record, which is usually not what you want for one-to-one:

params = { :member => { :avatar_attributes => { :icon => 'sad' } } }

Alternatively, you can use the ‘update_only’ option. This option will ensure that an existing record will always be updated, even if the ID is not specified:

accepts_nested_attributes_for :avatar, :update_only => true

available column types

Rails 3.0.9 update for RobinWu’s post

Available column types:

:string, :text, :integer, :float, :decimal, :datetime, :timestamp, :time, :date, :binary, :boolean

Example:

MyClass < ActiveRecord::Migration

def change
  create_table :myclass do |t|
    t.string :name
    t.text :content
end

end

Typo in example above

You aren’t mistaken. That is an error in the example with the block above. There’s an extra ‘(’ character.

RailsCast about Responders

See Ryan Bate’s excellent RailsCast #224 about Responders in Rails 3.x: http://asciicasts.com/episodes/224-controllers-in-rails-3

RE: Don't Use to_formatted_s(:db) on an Array of IDs

The reason it doesnt work @joshuapinter for IDs is because if you look at the source:

case format
  when :db
    if respond_to?(:empty?) && self.empty?
      "null"
    else
      collect { |element| element.id }.join(",") # look at this line
    end
  else
    to_default_s
end

It maps/collects the object ids and then joins them using a comma ; so in the case of 60 for instance :

60.object_id #=> 121

60.id #=> 121

:url conflicts with :format

If you are passing both :url and :format, url overwrites the use of format, so you’ll need to pass it in the url like so:

form_for user, :url => user_path(@user, :format => :json)

Clear form

for clear a form, use this:

<%= f.submit "clear", :type => "reset" %>

Typecasting return values

A better way to typecast the result array is to use AR’s typecasting capabilities. Example:

column = Company.columns_hash['id']
select_values("SELECT id FROM companies LIMIT 3").map do |value|
  column.type_cast(value)
end