Lasse Bunk's weblog

Saving multiple models only if all are valid

lassebunk — Fri, 05 Mar 2010 16:32:54 +0000

I’m doing a website where I have multiple (or, two) models in one form. My goal is to save both of these models at once, but only if they both validate. I want this done easy, idiomatic and terse. This is what I’ve come up with:

# in the controller
def new
  @account = Account.new
  @user = User.new
end

# in the view
<% form_for @account do |f| %>
  <%= f.error_messages %>
  
    <%= f.label :name %>

    <%= f.text_field :name %>
  
  <% fields_for @user do |u| %>
    <%= u.error_messages %>
    
      <%= f.label :name %>

      <%= f.text_field :name %>
    
  <% end %>
  
    <%= f.submit "Create account" %>
  
<% end %>

And after you press ‘Create account’:

# in the controller
def create
  @account = Account.new(params[:account])
  @user = User.new(params[:user])

  # this is where the magic starts
  if [@account, @user].map { |rec| rec.valid? }.all?
    [@account, @user].each { |rec| rec.save! }
    redirect_to account_path
  else
    render :new
  end
end

This way each model will only be saved if all models validate.

Update: We could also do this even nicer by writing a method:

# in your ApplicationController
def save_all(*models)
  if models.map { |rec| rec.valid? }.all?
    models.each { |rec| rec.save! }
    true
  end
end

# in your create method
if save_all(@account, @user)
  redirect_to account_path
else
  render :new
end

I’m not entirely sure this code should go in the ApplicationController but for now, that’s where it’ll be.

Outputting the flash to views and layouts

lassebunk — Fri, 05 Mar 2010 16:13:20 +0000

Here is a simple way of outputting the first message in the flash (because I didn’t want it to output both flash[:error] and flash[:notice] at the same time).

# in the controller
flash[:notice] = "Thanks for signing up!"

.. and…

# in the view
<% flash.detect do |type, text| %>
	
		<%= text %>
	
<% end %>

The detect method will return the first key/value pair of the flash where the block doesn’t return false. However, that’s not what we’re using it for – we’re using it to make sure we only get the first element.

Hope this is useful.

Using Sinatra to serve smaller (than Rails) applications

lassebunk — Thu, 25 Feb 2010 14:19:55 +0000

So, maybe you’ve been coding Rails for a while and wondered – “do I really need this full stack framework to serve even small applications?”. Well, no you don’t :-)

Check out Norbauer’s DNS Tools (and on Github). It’s a small set of easy to use DNS tools. So small it would be overkill to serve it using Rails.

Norbauer’s using Sinatra to serve the app.

Start by installing the gem:

$ sudo gem install sinatra

After that it’s as simple as this:

# myapp.rb
require 'rubygems'
require 'sinatra'

get '/' do
  "Welcome to my homepage!"
end

get '/contact' do
  "My contact info is..."
end

At your terminal:

$ ruby myapp.rb
== Sinatra/0.9.4 has taken the stage on 4567 for development with backup from Mongrel

Now you can view it in your browser at http://localhost:4567 and http://localhost:4567/contact. Simple.

This is great for hosting apps from your command line (for example check out Taps) but what if you wanted to serve it like you would a Rails app?

Well, then you’d be using Rack.

Create a file named config.ru in the same folder as myapp.rb:

require 'myapp'
run Sinatra::Application

Now you can deploy your application as you would if it was written in Rails (thanks to config.ru).
If you want to check this setup at your localhost, run the following:

$ sudo gem install rack # make sure you have Rack installed
$ rackup # run the Rack application using config.ru

It’s as easy as that! Great for hosting small applications.

Also see:

Using Paperclip and jpegcam to get pictures from your webcam into Rails

lassebunk — Thu, 18 Feb 2010 14:45:49 +0000

Here’s how to get pictures from your webcam into Rails using the Paperclip plugin and jpegcam.

What we will do is create a Photo model and a Photos controller with actions new, upload and create to take care of the image creation.

Start by creating a new Rails application:

$ rails webcam_app
$ cd webcam_app

Create the Photo model:

$ script/generate model Photo description:string
$ rake db:migrate

Create the Photos controller:

$ script/generate controller Photos

Edit config/routes.rb to contain a photos resource:

map.resources :photos, :only => [:index, :show, :new, :create], :new => { :upload => :post }

Download jpegcam and put webcam.js in your public/javascripts folder and webcam.swf and shutter.mp3 in your public folder.

Create the layout file app/views/layouts/application.html.erb and insert the following HTML:


  
    <%= javascript_include_tag :defaults %>
    <%= javascript_include_tag 'webcam' %>
  
  
	  <%= yield %>

Next, create app/views/photos/new.html.erb and make a div for the webcam contents:

And the actual webcam javascript:

That will run the actual webcam so you can see yourself :) But for taking a picture, we’ll need to add the following button:

Now when you click the button, the webcam image will be posted to /photos/new/upload. Try it out:

$ script/server

and go to http://localhost:3000/photos/new.

Let’s add some code for handling the upload.

The webcam.swf just uploads a bunch of jpeg data so we’ll need to get a hold of the raw post data. That’s done with Rails’ request.raw_post. In your PhotosController:

def upload
  File.open(upload_path, 'w') do |f|
    f.write request.raw_post
  end
  render :text => "ok"
end

private

def upload_path # is used in upload and create
  file_name = session[:session_id].to_s + '.jpg'
  File.join(RAILS_ROOT, 'public', 'uploads', file_name)
end

Remember to create the public/uploads folder.

Now, back to app/views/photos/new.html.erb. Create the following at the bottom of the view:

<% form_for Photo.new, :html => { :style => "display: none;" } do |f| %>
  
    <%= f.label :description %>

    <%= f.text_field :description %>
  
  
    <%= f.submit "Save the photo" %>
    or <%= link_to "Take another", new_photo_path %>
  
<% end %>

In your javascript just below the webcam div, insert the following function:

function upload_complete(msg) {
  if (msg == 'ok') {
    $('new_photo').show();
    $('photo_description').focus();
  } else {
    alert('An error occured');
    webcam.reset();
  }
}

And add the following webcam code:

webcam.set_hook('onComplete', 'upload_complete');

Now when you take a picture you will get a new photo form for entering a description. If something goes wrong, the webcam will be reset so you can try again. This might also be a good time to check your logs.

Now we have the upload (see for yourself in your public/uploads folder) but we still need to add Paperclip to the model.
Start by installing the plugin:

$ script/plugin install git://github.com/thoughtbot/paperclip.git

In the Photo model:

class Photo < ActiveRecord::Base
  has_attached_file :image, :styles => { :medium => "300x300>", :thumb => "100x100>" }
end

For this to work, we need to add some necessary Paperclip columns to our Photo model:

$ script/generate paperclip photo image
$ rake db:migrate

Now we can show photos like this:

<%= image_tag photo.image.url(:thumb) %>

We just need to save the photos first. Add the following to your PhotosController somewhere above the private keyword:

def create
  @photo = Photo.new(params[:photo])
  @photo.image = File.new(upload_path)
  @photo.save

  redirect_to @photo
end

def show
  @photo = Photo.find(params[:id])
end

def index
  @photos = Photo.all
end

In app/views/photos/show.html.erb:

Photo
<%= image_tag @photo.image.url(:medium) %>

  Description:

  <%=h @photo.description %>


  <%= link_to "Take a new picture", new_photo_path %>
  | <%= link_to "See all pictures", photos_path %>

And last but not least in app/views/photos/index.html.erb:

All photos

  <% @photos.each do |photo| %>
    <%= link_to image_tag(photo.image.url(:thumb)), photo %>
  <% end %>


  <%= link_to "Take a new picture", new_photo_path %>

Now start your script/server if it isn’t already, go to http://localhost:3000/photos – aaannnd.. it works!

Streaming radio on iPhone or iPod Touch

lassebunk — Sat, 10 Oct 2009 10:38:40 +0000

I have found a really great little program called FStream that works for streaming M3U and PLS stations on the iPhone and iPod Touch.

The concept is that you add one or more radio stations. You can do it directly in the app or you can enable a web administration interface that works really great:

I really like the application because it’s stable, and it simply does what it does; plays internet radio. Thanks SourceMac.

Check out FStream on iTunes

Three months on the Mac stack

lassebunk — Thu, 24 Sep 2009 13:39:45 +0000

It’s actually four months now – since May 1st – but I’ve been wanting to write this article for a month. Hence the – somewhat misleading – title.

I bought my MacBook on May 1th after viewing a screencast where a guy sets up a blog in 15 minutes using Ruby on Rails. I immediately said to my stepdad: “I’m going to buy a Mac and learn Ruby on Rails!”

And so I did – the day after, I bought a Mac.

I’ve always been a dedicated user of Microsoft’s products. First C64, then Amiga, then Mac, then PC. I liked the way everything was tested and came from one place, unlike open source. I’ve always been saying stuff like “I like to pay for my software because then I’m be sure about the quality.” – but in reality, everyone who uses Windows and other Microsoft products know that this isn’t always the case.

So I bought the Mac, and the first thing that surprised me, was how much of day-to-day work was done in the Terminal, or command line. When I installed Ruby on Rails, it was via command line; when I installed plugins, it was via command line. Evererything command line. :-)

Over the next few days I began to get a hang of it. I bought a couple of domain names and signed up for a slice at Slicehost – because I had read some job description that said that you should’ve at least tried to use a whole day of setting a slice.

Coming from Windows, Linux is a whole other deal to setup. I used a lot of the Slicehost articles that guides you through the whole process from setup and security to getting your slice to run as a webserver.

In the beginning I was a little nervous about all the command lines, if they would really work and so one. But the more you try it, the more calm you get. It just works! And lucky me there was a lot of helpful articles about Unix and Linux commands out there (just search for the command on Google).

Since starting out on the Mac, I’ve learned a multitude of things:

Setting up an Ubuntu slice at Slicehost.
Setting up a web server.
Setting up Ubuntu Netbook Remix on my netbook.
Setting up Ubuntu server at home, also on my netbook – which now functions as my testing server.
Programming a little PHP – see Tweet My Cam.
Programming Ruby on Rails.
Tweaking some Java code, compiling and signing a java applet in one day – see a demo here.
Download and compile software (configure, make, make install).
Submitted a patch to a Ruby on Rails plugin on Github.
Setting up Wordpress and Wordpress Mu blogs and making my own theme – see my private blog and private work blog.
Setting up a Subversion repository at XP-Dev.com.
Using the Subversion repository :-)
Loving Textmate as my favorite editor – also over Visual Studio.
Plus a bunch of other things.

In short I’ve learned so much about the open source world that just wasn’t that easy on the Microsoft platform.

I still use Microsoft Windows and other products, but now it’s through VMware Fusion on the Mac.

I’m happy about the Mac because OS X is very unobtrusive, fast operating system and what it does, it does very good. But at the same time, I also want a netbook that’s easier to carry, so I may end up running both systems for different purposes (unless I’m just installing Ubuntu on the netbook too ;-)).

Hope you found this post interesting – I wrote it to tell about a beautiful (yak, I know) progress from Windows to Mac and Linux. Thumbs up if this has made you want to try it too. And please tell me in the comments. :-)

Launched Notesapp

lassebunk — Tue, 22 Sep 2009 17:06:35 +0000

I have just launched Notesapp which is an application for saving notes online – much like Delicious but with notes instead of links.

Hope you’ll try it – it’s at notesapp.net.

PS. I’ll expand the application to support various text formats and do an open API, but right now I just have other stuff to do. :-)

Just launched Tweet My Cam

lassebunk — Mon, 21 Sep 2009 14:19:13 +0000

I just launched Tweet My Cam, a simple web service to post pictures from your webcam to Twitter.

Check it out: tweetmycam.com

How to use U.S. versioned Bing from Europe

lassebunk — Sat, 19 Sep 2009 19:18:28 +0000

So – you read about Bing on Mashable and want to try out the cool new features. But what happens when you go to Bing? You see nothing! That’s because some of the really cool features are only available from within the U.S.

What I do is that I use a U.S. proxy service so that the IP that Bing sees is in reality the IP of the proxy service – as if I was browsing the site from somewhere in the U.S.

One great proxy service is HideMyAss.com which works really well. It has a lot of popup windows but if you can live with that, it really works great.

So: Go to HideMyAss.com and type in www.bing.com – it works!

Clipboard java applet

lassebunk — Tue, 04 Aug 2009 20:49:14 +0000

The source code my previous post about a clipboard image applet is now available here: PasteImageApplet.zip

The code lets you post images from your clipboard directly to the webserver to avoid the need to go through Photoshop or another image application.

When you compile your own applet using javac, you’ll need to sign it in order to be able to get access to the clipboard. (I have signed the applet contained in the zip and the certificate expires 6 months from July 19th, 2009, around January 19th, 2010).

If you find it useful or somebody else has already done this (and somebody surely has, but I didn’t have any luck finding it on Google), please write me in the comments.

Thanks.
- Lasse