Recent notes

The last existing version

It says: The last existing version, and yet when I run a rails console in a 3.0.17 and try the method, it just works. Or does it mean it was never worked on past 2.3.8 ?

What artemave said.

I’d remove my original note if I could, but I can’t see a way how.

Selected parameter

If you want multiple options to be selected by default you can pass an array of values as “selected” option. It should be obvious, but odradek’s and batarski’s notes can confuse somebody in this case.

attributes that have the same names as options

For reasons that are beyond my comprehension, this piece of code

class Working

  include ActiveModel::Validations

  attr_accessor :format

  validates :format, :presence => true, :format => { :with => /\AWorking/ }

end

works (NOTE: it has an attribute that has the same name of an option), while this

class NotWorking < ActiveRecord::Base

  validates :format, :presence => true, :format => { :with => /\ANot Working/ }

end

does not (assuming that you have a legacy db in which you can’t change the names of the columns). It throws an ArgumentError at you. However, a crude hack is to add an explicit accessor to the :format method, like this

class WorkingAgain < ActiveRecord::Base

  validates :format, :presence => true, :format => { :with => /\AWorking again/ }

  def format
    read_attribute(:format)
  end

end

Any explanation is welcome.

Specifying an accept header in your tests

To specify an accept header, you need to pass it in the second hash like this:

get '/url', nil, {'HTTP_ACCEPT' => 'application/json'}

The documentation says everything is uppercased and HTTP_ is appended when necessary, but that wasn’t working for me.

is now a subclass of Hash that preserves order (or _is_ a Hash if running Ruby 1.9 or greater)

You might not realize it preserves order because it delegates inspect to its super-class, Hash, which doesn’t preserve order. But you will see that order is preserved if you iterate or use the keys or values methods:

>> names = ['Amy Irving', 'Jane Doe', 'John Doe', 'John Updike', 'Susan Anthony']
>> ordered = names.group_by { |name| name.split.first }
=> #<OrderedHash {"John"=>["John Doe", "John Updike"], "Amy"=>["Amy Irving"], "Susan"=>["Susan Anthony"], "Jane"=>["Jane Doe"]}>

# (note that the inspect above is in undefined order)

>> ordered.keys                          # will be ordered properly
=> ["Amy", "Jane", "John", "Susan"]

>> ordered.each { |first, full| puts first; full.each { |name| puts "  #{name}" } }  # will be ordered properly
Amy
  Amy Irving
Jane
  Jane Doe
John
  John Doe
  John Updike
Susan
  Susan Anthony

#performed? is an option when getting ActionController::DoubleRenderError

You can avoid `ActionController::DoubleRenderError (Can only render or redirect once per action)` with `#performed?`

For example

def index
  redirect_to not_found_path unless authenticated?
  render :action => 'update' unless performed?
end

If you happen to face some weird rounding issue...

i.e.

helper.number_to_currency(187)
=> "190 kr"

check out your… translations! Especially ‘significant’ key… In my case it was

number:
   currency:
     format:
       significant: 'false'

that broke rounding. It should have been

number:
   currency:
     format:
       significant: ! 'false'

And now it works perfectly

helper.number_to_currency(187)
=> "187 kr"

To add an ID to the form

Found this the hard way, but to add an ID to the form generated by form_tag, you must explicitly make hashes.

Add ID

<%= form_tag({:action => 'create'}, {:id => 'anID'}) %>

Showing the select with a value previously known

Enter the value in the ‘value to check if exist in the list’ section and the drop down should have that selected

Code example

select_tag "name",
options_for_select(list.collect{ [ text, value] },
            'value to check if exist in the list', 
            {:include_blank => true}

See also: Rack::Utils.parse_nested_query.

Note that CGI::parse does not attempt to create a multi-level object; that is, it basically ignores hard brackets in key names.

For a method that does deal with these, see Rack::Utils.parse_nested_query.

Bad Example

@nZifnab it is a bad example because an included module is basically a class.

module Mod
    def exit(code = 0)
        puts "Exiting with code #{code}"
        super
    end
end

include Mod

exit 99

produces

Exiting with code 99

Send with filename

The Content-Disposition response header holds the suggested attachment filename (i.e. “attachment; filename=fname.ext”)

Set the :disposition option to pass this name.

Controller

http = Net::HTTP.new(@page.host)
res = http.post(path, info.to_query, headers)
send_data res, :content_type => res.content_type, :disposition => res["Content-Disposition"], status: res.code

Clarification with use of update_all

I would like to point out that if you are on rails 2.3.11 or lower you will not be able to run ledermann code.

Ledermann Code

user.messages.update_all(:read => true)

If you are running 2.3 or later it you will have to use James code

James Code

Message.update_all({:read => true}, {:id => user.messages})

thanks guys for all the code help

Don't mix attr_accessible and attr_protected within single class.

Don’t use constructs like this one, they won’t work:

class User < ActiveRecord::Base
  attr_accessible :name
  attr_protected :id, :password_digest, :created_at, :updated_at, as: :admin
end

Instead, use the same method for all roles:

class User < ActiveRecord::Base
  attr_accessible :name
  attr_accessible :name, :login, as: :admin
end

—

You may want to add following to your `/config/initializers`:

class ActiveRecord::Base
  class << self
    alias :original_inherited :inherited
    def inherited subclass
      original_inherited subclass
      subclass.attr_accessible
      subclass.attr_accessible(subclass.attribute_names.map(&:to_sym) - [:id, :created_at, :updated_at], as: :admin)
    end
  end
end

Don't allow mass assignments on model

Replying to elfo’s comment, you can achieve it easier, just add following line to `/config/application.rb`.

config.active_record.whitelist_attributes = true

All attributes in all models will be mass assignment protected by default. You can still use attr_accessible or attr_protected to override it.

Skip validations

.

user.save(false)

will skip validations

Return value:

The result of this method is a hash of the following form:

{"table_field"=>"table value", "another_field" => 15, ...}

For example:

{"user_id"=>21}

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Custom serialization

It is possible to supply a class with own (de)serialization logic to the serialize call. Given object must respond to load and dump calls.

Following example serializes symbols into their string representation and store them in database as raw strings instead of their YAML representation, i.e. :pumpkin would be stored as ‘pumpkin’, and not as ‘--- :pumpkin\n’

Example

clas SomeModel < ActiveRecord::Base
  class SymbolWrapper
    def self.load(string)
      string.to_sym
    end

    def self.dump(symbol)
      symbol.to_s
    end
  end

  serialize :value, SymbolWrapper
end

Reports originally defined method names, not invoked names in Ruby 1.9.x

In Ruby 1.8.7, the reported method names were those of the methods actually invoked, so if #b was an alias for #a, and #b was called, it would be reported as “… in `b’”. In Ruby 1.9, the same invocation is now reported as “… in `a’”.

Unfortunately, this change disables the hack that could formerly be used to create a variant of __method__ that returns the method as actually invoked. The new __callee__ method is no help with that, because it is currently synonymous with __method__.

__callee__ and __method__ both return symbol when originally defined, not current

There has been some indication that __callee__ is intended to return the symbol with which the method was actually invoked, whereas __method__ returns name with which the method was originally defined, but __callee__ actually behaves identically to __method__ in Ruby 1.9.1 1.9.2, and 1.9.3.

This distinction is meaningful, because methods can be aliased after they are created.

In Ruby 1.8.7, it was possible (though) not convenient to get the name of the method as actually invoked, by calling another method that extracts the name from caller.first. Even that hack no longer works in Ruby 1.9 though, since it will return the originally defined method name as well.

ActiveModel::MassAssignmentSecurity::Error

Note that in the example shown in the documentation, `user.assign_attributes({ :name => ‘Josh’, :is_admin => true })` would raise a `ActiveModel::MassAssignmentSecurity::Error` and would not actually update user.name, contrary to what the example seems to demonstrate.

Don't allow mass assignments on model

To block all mass assignments on a model, it’s as simple as having an empty list of accessible attributes.

example

class Users < ActiveRecord::Base
   attr_accessible #none
end

Usage

In Rails 3.X console:

Rails.application.routes.recognize_path('/my_path')

How to handle dynamic controller class evaluation based on params

Possible with following snippet of code (for instance if each branch has some different controller logic, but if the controller is not present, it should fallback to default controller).

Advantages are so we do not have to make blank inherited controllers and routes for them, to do it with plain inheritance.

class ActionDispatch::Routing::RouteSet::CustomDispatcher < ActionDispatch::Routing::RouteSet::Dispatcher
  # These are the controllers that we should attempt fallbacks on
  FALLBACK_CONTROLLERS = /customer\/branch\/(projects|events)$/

  def controller(params, default_controller=true)
    # This defines when we want to attempt fallbacks pattern
    super unless params[:branch_id] && params[:controller].try(:match, FALLBACK_CONTROLLERS)
    controller_param = params[:controller]

    # Having these supplied, we handle controller evaluation by our own method...
    controller_reference_with_fallbacks(params[:branch_id], controller_param)
  rescue NameError => e
    raise ActionController::RoutingError, e.message, e.backtrace if default_controller
  end

  private

  def controller_reference_with_fallbacks(branch_id, controller_param)
    # This is how fallbacks are evaluated       
    controller_name = "#{controller_param.sub('/branch', "/branch/#{branch_id}").camelize}Controller"

    controller = ActiveSupport::Dependencies.reference(controller_name)

    begin
      controller.get(controller_name)
    rescue NameError => e  # If there is no specific class for given branch, fallback to original class
      controller_reference(controller_param)
    end
  end
end

ActionDispatch::Routing::Mapper::Mapping.class_eval do
  private

  # We do overwrite dispatcher class, that is used to evaluate controller classes from params
  def app
    ActionDispatch::Routing::Mapper::Constraints.new(
        to.respond_to?(:call) ? to : ::ActionDispatch::Routing::RouteSet::CustomDispatcher.new(:defaults => defaults),
        blocks,
        @set.request_class
    )
  end
end

Specify :host option in emails

Emails need a fully qualified URL (with domain). Use the :host parameter.

But note also that you need to specify a value that is not dependent upon the request context. http://api.rubyonrails.org/classes/ActionMailer/Base.html recommends setting a default host in application.rb For those of us who have development, test, staging and production environments, set in the environment-specific files, or in the :default hash in the mailer.

This applies to both +url_for(:host => “example.com”)+ and when using named routes as in +widgets_url(:host => “example.com”)+

Rails Guides

There is an excellent guide on the use of this method located here:

http://guides.rubyonrails.org/active_record_querying.html#conditions

Using Amazon Simple Email Service with ActionMailer

First of all, get all the necessary SES credentials and verify your email address.

Then, just edit your config/environments/*.rb files:

config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
    address: 'email-smtp.us-east-1.amazonaws.com',
    user_name: 'your-ses-smtp-user-name',
    password: 'your-ses-smtp-password',
    authentication: :login,
    enable_starttls_auto: true
}

And that’s it!

in rails3 StatusCodes have been moved to Rack::Utils

in rails3 StatusCodes have been moved to Rack::Utils