Recent notes

Tempfile extension

Code

f = Tempfile.new(['graph','.json'])

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

now they are built-in

in ruby 1.9 and afterwards, the to_enum and enum_for(synonym for to_enum) methods are buil-in to the language. so there’s no need to require that any more.

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.

Dup vs Clone difference

As for me main difference between .dup and .clone , that first one doesn’t not freeze result object if initial object was frozen.

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

Uses same arguments as Time#strftime

I believe this uses the same parsing format as strftime.

http://apidock.com/ruby/Time/strftime

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)

Loop through matches of your regular expression-based search

If you want to loop through the matches of a regular expression, String#scan is your friend. You can do something like this:

matches = '12345'.scan(/\d/)
matches.each do |m|
  puts m
end

# => 1
# => 2
# => 3
# => 4
# => 5

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

don't forget :root

You can rename the root tag if you don’t like what is being generated.

line_item.to_xml(:skip_instruct => true, :root => 'line-item')

require it

require ‘action_dispatch/testing/test_process’

select_values returns Strings for postgreSQL

Will return strings too when using postgreSQL and gem pg (0.11.0).

bug's fixed, though

in 3.1.0. it works in sqlite3 even, via nested query

but 3.0.3, 3.0.7-9 all broken

validating a database column acceptance

accept option should be set to true if you are validating a database column, since the attribute is typecast from “1” to true before validation

validates :terms,
  acceptance: {
    allow_nil: false,
    accept: true
  }

Unusual block calling

It is important to note that the block form of this method is unlike any other block form in Rails. You would expect this to work:

<%= f.label :terms_and_conditions do %>
  Accept <%= link_to_page 'Terms and Conditions' %>
<% end %>

But doing this ends up messing up the form (I ended up with the form repeating itself). Instead you need to do:

<%= f.label :terms_and_conditions do
  'Accept ' + link_to_page('Terms and Conditions')
end %>

Which is really only mildly better than not using the block form:

<%= f.label :terms_and_conditions,
  'Accept ' + link_to_page('Terms and Conditions') %>

You are actually better of using capture if your code lends itself to the first non-working form:

<%= f.label :terms_and_conditions, (capture do %>
  Accept <%= link_to_page 'Terms and Conditions' %>
<% end) %>

Or if you prefer brackets to parenthesis you can do:

<%= f.label :terms_and_conditions, capture { %>
  Accept <%= link_to_page 'Terms and Conditions' %>
<% } %>