As remote_function no longer exists in Rails 3, here is some handy substitution

<%= select_tag :assignee_id, options_for_select([["A",1],["B",2]]), :onchange => "$.post('#{model_singular_path(id)}', {'_method':'put', 'model_name[model_field]':this.value} );" %>

Y...

@tadman is wrong. There is a difference and, trust me, it can bite:

1.9.2 > [1,2,3,4].delete_if {|x| x > 10}

=> [1, 2, 3, 4] 1.9.2 > [1,2,3,4].reject! {|x| x > 10} => nil

That is, if reject! hasn't rejected anything, it returns nil.

This method will raise Errno::ENOENT on a broken symlink. You should probably rescue it every time you call this method.

I think what metavida meant was

User.find(1, 3) # ActiveRecord::RecordNotFound error not User.find_by_id(1, 3) # this will just return user 1

As an example of bansalakhil's explanation.

User.find_by_id(1) #=> #<User:0x3d54a3c @attributes={"id"=>1}> User.find_by_id(2) #=> #<User:0x3d519a4 @attributes={"id"=>2}> User.find_by_id(3) #=> nil User.find_by_id(1, 2) #=> an Array with 2 User instances User.find_by_id(1, 3) #=> an ActiveRecor...

If you're using PostgreSQL and you've changed schema, sometimes you need to know what schema you're in.

ActiveRecord::Base.connection.schema_search_path.split(",").first

for instance

class Student < ActiveRecord::Base
   named_scope :sophomore, :conditions => 'year=2'

   def self.eligible_to_vote
     select{|s| s.age >= 18}
   end

end

ss = Student.sophomore.eligible_to_vote

Of course such a method does not exist, however we can simulate it easily

%w(a b c).to_enum(:each_with_index).map{|a,i| "#{a}, #{i}"} => ["a, 0", "b, 1", "c, 2"]

====

= pluralize(item.categories.count, 'Category').sub(/\\d+\\s/, '')

Given I have following classes

class User < ActiveRecord::Base end

class ::User::Agent < ::User has_many :leads, :as => :creator end

I would expect, that running

User::Agent.first.leads

will result in following query

SELECT "leads".* FROM "leads" WHERE ("leads".creator_id = 6 AND...

Somehow, If you want to extend the behaviour of attributes=,

alias_method_chain does not work. It simply breaks (could not find out how exactly).

def attributes_with_some_feature=(new_attributes, guard_protected_attributes = true)
attributes_without_some_feature=(new_attributes, guard_prot...

change_column will not query to replace the null values when you change null to false, even if you have a default set. This may cause the query to fail (may depend on the database used).

change_column_null will optionally take a value to replace nulls if you are setting null to false. If you want t...

for some reason this method only works on relation objects, not directly on an AR class.

# doesn't work
User.offset(3).limit(1)

# does work
User.limit(1).offset(3)

there's an closed ticket for this here http://rails.lighthouseapp.com/projects/8994/tickets/5688-modeloffsetxlimitx-u...

add_index is a different method. I think this is just a bug and it's broken.

option like :greater_than still supported

use like this

==== Code example

validates :position, :presence => true, :numericality => {:greater_than => 0}

Don't use this method unless you're sure your string isn't nil. Instead use the raw() method, which wont raise an exception on nil.

Check the ClassMethods -- the docs on filters are there.

Needs to be paired with respond_to at the top of your class.

class MyController < ApplicationController
respond_to :js, :html

Another technique to use when you need to send an array parameter is pass in the :multiple option.

check_box("puppy", "commands", {:multiple => true}, "sit", nil)
check_box("puppy", "commands", {:multiple => true}, "fetch", nil)
check_box("puppy", "commands", {:multiple => true}, "roll_...

Use +sanitize+ or +connection.quote+ instead.