codemilan

require 'file_size_validator'
class Song < ActiveRecord::Base
  mount_uploader :attachment, AttachmentUploader

  validates :attachment, :presence => true, 
  			:file_size => {:maximum => 2.megabytes.to_i}
end

when I submit form without file or empty form it gives error :

codemilan

In this article, I'll walk through a basic Rails (3.2.x) setup for creating a nested resource for two models. Nested resources work well when you want to build out URL structure between two related models, and still maintain a RESTful convention. This code assumes you are running RVM to manage Ruby/Gem versions, and Git for version control.

Creating a new Rails project

$ mkdir family # create rvm gemset 
$ echo "rvm use --create ruby-1.9.2@family" > family/.rvmrc 
$ cd family # install rails 
$ gem install rails # create new rails project 
$ rails new . # version control 

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class ActiveRecord::Base
  
  def self.import!(record_list)
    raise ArgumentError "record_list not an Array of Hashes" unless record_list.is_a?(Array) && record_list.all? {|rec| rec.is_a? Hash }
    return record_list if record_list.empty?

    (1..record_list.count).step(1000).each do |start|
      key_list, value_list = convert_record_list(record_list[start-1..start+999])
      sql = "INSERT INTO #{self.table_name} (#{key_list.join(", ")}) VALUES #{value_list.map {|rec| "(#{rec.join(", ")})" }.join(" ,")}"
      self.connection.insert_sql(sql)

codemilan

• Dynamic Dispatch
• Dynamic Method
• Ghost Methods
• Dynamic Proxies
• Blank Slate
• Kernel Method
• Flattening the Scope (aka Nested Lexical Scopes)
• Context Probe
• Class Eval (not really a 'spell' more just a demonstration of its usage)
• Class Macros

codemilan

Custom Date Formats in Rails

Quick guide on printing pretty dates in Rails

codemilan

# with multiple collections + commands for renaming back the collections

require 'mongo'

# Stop writing to your database.
# Then, for each collection:
# Specify the DB and COLLECTION you want to convert.
# Will insert all modified documents into a new collection
# called 'new_' + old_collection_name.
# Then you can delete the old collection and rename the new one

codemilan

# app/controllers/sessions_controller.rb

class SessionsController < Devise::SessionsController

  # This controller provides a JSON version of the Devise::SessionsController and
  # is compatible with the use of SimpleTokenAuthentication.
  # See https://github.com/gonzalo-bulnes/simple_token_authentication/issues/27

  def create
    # Fetch params

codemilan

require 'rubygems'
require 'bundler/setup'
require 'mongoid'

Mongoid.configure do |config|
  config.master = Mongo::Connection.new('localhost', 27017, :logger => nil).db('mongoid-test') 
end

class A
  include Mongoid::Document

codemilan

Adding an audit log to your Rails app

If you have any sort of administrative interface on your web site, you can easily imagine an intruder gaining access and mucking about. How do you know the extent of the damage? Adding an audit log to your app is one quick solution. An audit log should record a few things:

• controller entry points with parameter values
• permanent information about the user, like user_id
• transient information about the user, like IP and user_agent

Using the Rails framework, this is as simple as adding a before_action to your admin controllers. Here’s a basic version that I’m using in production.

codemilan

class Api::UploadsController < ApiController

  def create
    @upload = Upload.new(upload_params)
  ensure
    clean_tempfile
  end

  private