Notes posted by Vidmantas

Pass a block

While this example is not so obvious on first look what the block passed does, here’s a small explanation:

when the block is passed to this function, the uniqueness is checked based on a value returned by that block.

For example if it’s array of objects with “user_id” method, then this would be:

tasks.uniq{|t| t.user_id } # returns only tasks with unique user_id 

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

Works with scoped too

It’s also available to use after scope chain too, like in any other AR action, for example:

User.where('age > 69').delete_all

If on Rails 3

If you’re on Rails 3, you should look into

http://apidock.com/rails/ActiveRecord/Relation/update_all

Default fallback

You can specifly :default option which is useful when the translation is not found. For example:

t(:this_translation_doesnt_exist, :default => 'Ooops!')
# => Ooops!

Or even any number of “fallbacks” - the first not nil is returned:

t(:missing, :default => [:missing_too, :existing, 'Sad panda'])
# => :existing translation

Good introduction to Rails I18n is http://guides.rubyonrails.org/i18n.html

How to set default value to NULL

To set default value to NULL you can use change_column method instead, for example:

change_column :suppliers, :qualification, :string, :default => nil

Just make sure you don’t change data type accidentally ;-)

Do not forget to add indexes

Don’t forget to add indexes to HATM table:

add_index :developers_projects, [:developer_id, :project_id]

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])

Common options

“Common options” mentioned here is default PrototypeHelper options documented in link_to_remote

This means you can use :loading, :loaded, :failure, :success, etc in observe_field.

Not implented yet

According to this method’s source, change_column_default is not implemented as well as change_column

If you're not using resource

If you don’t use resource for your remote_form_for, then :url option is necessary.

For example:

<% remote_form_for "not_resource" do |f| ... %> 

won’t work. But with :url option, it will:

<% remote_form_for "not_resource", 
     :url => { :controller => "recommend", :action => "send" } do ... %> 

Rake tasks for gem dependencies

You can manage installation and other tasks for these dependencies with rake tasks, for example:

rake gems:install              # Installs all required gems for this application
rake gems:unpack               # Unpacks the specified gem into vendor/gems

To get all rake tasks about gems:

rake -T gems

Update element after remote call

Not mentioned in the documentation, you can add :update option to the remote_form_for and pass the id of element you’d like to update after ajax action as you do with link_to_remote, for example:

<% remote_form_for "comment", :update => "form" } do |f| %>
  # your form here
<% end %>

Or

<% remote_form_for "comment", :update => {:success => "form", :failure => "errors"} do |f| %>
  # your form here
<% end %>

Examples

@articles = cache(‘articles’) do

Articles.latest 

end

Or:

@articles = cache([‘articles’, user.id], :expires_in => 15.minutes)

# Advanced Rails Recipies says: "expires_in option works only with memcached store"
Articles.latest

end

Also if you’d like to have short ‘cache’ call in your model you can have it - add the following method to the model:

def cache(key, options = {})

ActionController::Base.cache_store.fetch(key, options) { yield }

end

Multipart form

Don’t forget to add :multipart => true if you have file upload in your form.

<% form_for "user", :html => { :multipart => true } do |f| %>

You can turn off dirty objects

If you expierence problems with dirty objects you can turn it off:

ActiveRecord::Base.partial_updates = false

Moved to plugin "auto_complete"

This helper was moved to plugin “auto_complete” - http://svn.rubyonrails.org/rails/plugins/auto_complete/

Multiple filter methods with :only, :except

Notice that this methods accepts *filters param, so you can pass array of methods with :only or :except too

Example

before_filter [:authorize, :set_locale], :except => :login

2.1 sets UTC time by default

Rails 2.1 sets hour select to UTC time value, not local server time by default. So if you’re not in UTC time zone don’t forget to specify timezone in your config/environment.rb: config.time_zone = 'Vilnius'