Tuesday, 4 October 2011

Ajax redirects with devise

When devise times out, the user should be forced to log in again. This works fine when the user attempts to access my app using an html request, but ajax requests were bringing up the http_authentication pop-up box from the browser. Googling around suggested various ways of dealing with this, all of which seemed to involve a lot of unnecessary work. Just putting
// Set up a global AJAX error handler to handle the 401
// unauthorized responses. If a 401 status code comes back,
// the user is no longer logged-into the system and can not
// use it properly.
statusCode: {
401: function(){

// Redirect the to the login page.
location.href = "/";;

in the application.js file solved the problem.

Tuesday, 13 September 2011

Starting the console ready for rails

Every time I start my computer I spend a couple of minutes getting the console set up the way I want it - I need spork and autotest running, I need the rails console and server - oh and I like to run both dev and production versions of these. It all takes time. Time to make it better.

In response to a question on stackexchange I got an answer that I've adapted. This requires adding the line

eval "$BASH_POST_RC"

at the end of .bashrc

Then in System > Preferences > Startup Applications
click on 'Add'
Name: Rails console

gnome-terminal --working-directory="/home/chris/development/bureaurails/trunk/server" --tab --title=Terminal --profile=Rails --tab --profile=Rails --title="Dev Console" -e 'bash -c "export BASH_POST_RC=\"rails console\"; exec bash"' --tab --profile=Rails --title="Dev Server" -e 'bash -c "export BASH_POST_RC=\"rails server\"; exec bash"' --tab --profile=Rails --title=Tail -e 'bash -c "export BASH_POST_RC=\"tail -f log/development.log\"; exec bash"' --tab --profile=Rails --title=Autotest -e 'bash -c "export BASH_POST_RC=\"bundle exec autotest\"; exec bash"' --tab --profile=Rails --title=Console -e 'bash -c "export BASH_POST_RC=\"rails console production\"; exec bash"' --tab --profile=Rails --title=Server -e 'bash -c "export BASH_POST_RC=\"rails server -e production -p 4000\"; exec bash"' --tab --profile=Rails --title=Spork -e 'bash -c "export BASH_POST_RC=\"bundle exec spork\"; exec bash"'

Comment: All you ever wanted in a rails console

Saturday, 7 May 2011

Creating word documents in rails

This week, I needed to create a word document from data in a rails app. Needless to say, there is not a windows machine in sight. After a bit of googling around and thinking about maybe trying to use OpenOffice to do some of the heavy lifting I came across a couple of posts that suggested it might be possible to do what I needed by creating a docx file that could be used as a template, and then editing it. After all, a docx file is just a zip file with a bunch of xml files inside ...

Levente Bagi has a nice solution but it didn't really meet my needs, and seemed overly complicated in places. There was also this blog article which outlined the technique but didn't have a lot of detail. My problem was that I had to extract a bunch of stuff from an active record object (an Event) and then iterate through several associated objects (Event has_many Days, has_many Providers). So I ended up rolling my own - hopefully these notes will help anyone following on behind.

First lesson - don't try and use rubyzip or zipruby to compress the files when creating the docx file. For reasons I didn't really investigate, they don't work. I'm guessing the default compression is wrong for docx files, but don't have the stamina to wade through the documentation. Use system zip instead.

The approach I took was this:
  1. Create a template. Using MS Word, make a document that is the sort of thing you want to create programatically. I originally wanted to add images but this complicates things unnecessarily.
  2. Save this as a docx file.
  3. Unzip the docx file. You get a folder containing several subfolders. One of these is called word, and inside that is a file called document.xml. Open it up with something that will format xml nicely - I used netbeans. First I found the data that needs to be extracted from the Event object. I replaced that with a new xml node containing the name of the method I wanted to call on the Event object as text so in place of
  4. <w:t>My event</w:t>

    I had


    Continue with the same node name for all the methods to be called on this object
  5. Next find the chunk of html that represents the associated object. We are going to need to cut this out and put it in a new xml document so that we can iterate over it. So we create a new empty document with the same namespace definitions as in document.xml, add a new node called <fragment/> and then paste the text you cut from the template document inside. In place of the cut text in the master template, add a new node - in my case since the cut text will display information about the each day of the event, I called the node <days/> Now work through the fragment and add a new xml node containing the name of the method I wanted to call on the Day object as text so in place of

    <w:t>Sat May 7th 2011</w:t>

    I had


    One refinement I needed to make was to pass an index and count for each associated object so that I could have headings like "Day 1 of 5" - just as before, I added nodes to the template where I needed these to appear.
  6. Repeat for other associated objects
  7. Now we need to create a new word document using these pieces. I created a method on the Event object
     def create_docx
    #substitute fields in main template
    doc = substitute(f,self)

    self.days.each_with_index do |day, i|
    doc.xpath("//days").before(substitute(f,day, i, self.days.size).xpath("//fragment").children)
    self.providers.each_with_index do |provider, i|
    doc.xpath("//providers").before(substitute(f,provider, i, self.providers.size).xpath("//fragment").children)
    doc = doc.to_s.gsub(/(\n|\t|\r)/, ' ').gsub(/>\s*<').squeeze(' ') build_docx(doc)

    Let's go through this line by line. We read in the template.xml file, and call substitute with the file and self as parameters - we'll look at that method later. Then we do the same with the associations - read the template, iterate over the associated objects, call substitute. Then we remove the marker tags, compress the xml file to remove any whitespace we don't need, and build the docx file. Easy.

    So what about the substitute method. It could hardly be simpler. Nokogiri makes it easy to replace the marker nodes we added with the content we want. Find the "insert" node, get the text it contains, call the method of that name on the object and replace the node with the result. Similarly, replace the index and count nodes with the parameters we passed in.
    def substitute(xmlstring,obj, i = 0, count = 1)
    doc= Nokogiri::XML(xmlstring.clone)
    doc.xpath("//insert").each do |n|
    n.parent.content= obj.send(n.text.to_sym)
    doc.xpath("//index").each do |n|
    n.parent.content= i + 1
    doc.xpath("//count").each do |n|
    n.parent.content= count

    Finally, the build_docx method is essentially stolen from Levente Bagi.
    def build_docx(content)
    filename="#{self.event_organiser.fd_name}_#{self.fd_event_name}".gsub(/\s*/, '')
    in_temp_dir do |temp_dir|
    system("cp -r lib/word_template_files #{temp_dir}/plan_report")
    open("#{temp_dir}/plan_report/word/document.xml", "w") do |file|
    system("cd #{temp_dir}/plan_report; zip -r ../#{filename}.docx *")
    system("cp #{temp_dir}/#{filename}.docx /home/chaser/downloads")

    def in_temp_dir
    temp_dir = "/tmp/docx_#{Time.now.to_f.to_s}"
    system("rm -Rf #{temp_dir}")

As mentioned at the start of this post - I originally hoped to be able to add images to this document - but that would require understanding enough about the way docx files handle assets and frankly the users will probably want to change the images and layout to suit their needs so it's almost certainly not worth it. It would be nice to try though ...

Thursday, 16 September 2010


I've been working quite a bit with Devise over the last week or so. I'm rewriting something that used to be a desktop application and turning it into a web app. The users currently have a seat-based licencing arrangement - 5 users, 10 users etc. Keeping this arrangement in a web application has proved a bit tricky. There are several posts in the devise group that suggest this is a fairly common requirement, but no obvious solutions. So here's my first hack at it - I've simply added one more method call to the resource inside the DatabaseAuthenticatable authenticate! method

require 'devise/strategies/authenticatable'

module Devise
module Strategies
# Default strategy for signing in a user, based on his email and password in the database.
class DatabaseAuthenticatable < Authenticatable
def authenticate!
resource = valid_password? && mapping.to.find_for_database_authentication(authentication_hash)

if resource && resource.licenced? && validate(resource){ resource.valid_password?(password) }


Warden::Strategies.add(:database_authenticatable, Devise::Strategies::DatabaseAuthenticatable)

Then in the resource model - in this case the User model - I can have a licenced? method that checks whether the user has a licence to access the system. The method looks like this:

def licenced?
not_logged_in? and has_licence?

Next I added a 'last_signed_out_at' field to the resource record and override the destroy method in the Devise::SessionsController.

def destroy
current_user.update_attribute(:last_signed_out_at, Time.now) rescue nil
set_flash_message :notice, :signed_out if signed_in?(resource_name)

On its own this is not enough to check whether the user is logged in, because they may just have closed the browser or their session may have timed out. We also need the fields added by the Trackable and Timeoutable modules. Together these changes allow us to write a not_logged_in? method in the User model

def not_logged_in?
ok = current_sign_in_at.nil? || last_request_at.nil?
ok = ok || last_request_at.to_i < Time.now.to_i - Devise.timeout_in.to_i rescue nil
ok= ok || last_signed_out_at > current_sign_in_at rescue nil

Finally we need to decide whether the user is licenced. This will vary depending on the application of course. In our case, an event can have any number of users but only licence_count users can be logged in at the same time, so in the User model

def has_licence?
event.logged_in_users < event.licence_count

And finally, we need to know how many users are logged in for a given event. In our case an event has_many users, and in the Event model I just iterate through all the users and count the ones that are signed in

def logged_in_users
users.inject(0){|count, u|
count+= 1 unless u.not_logged_in?

If I can find the time and there is any interest I will try and bundle this up into a stand-alone extension but for now just putting it out there ...

Wednesday, 25 August 2010

Testing with devise

Today I ran across a problem getting tests to pass with Devise. There were in fact two issues. First, in rails 3 the Gemfile does not stipulate the order in which gems are loaded and this can mess things up a bit. Especially with mocha, which I use for mocking and stubbing.

This post describes the issue.

To solve the problem I put

require 'mocha'
include Devise::TestHelpers

at the end of test/helper.rb

But the sets still didn't pass ....

The other problem to which the solution was more obvious when I actually thought about it was because I am using confirmable. So the setup needed to be:

def setup
@user = users(:one)
sign_in @user

Friday, 20 August 2010

i18n in rails 3

Well it's been a long time, but I'm going to make an effort to do more blogging now that rails 3 is almost here - partly to keep track of what I need to remember - but also because it might be useful to others.

I'm upgrading a big app to rails 3 before we go live with it - and of course there are a few glitches. Mostly these are to do with gems and plugins that don't work - more on them when I get to them. But the first big hiccup was internationalization. The app I'm upgrading is fully internationalized - but when I got the front page up i got things like

translation missing: 'en'::character varying, devise, sessions, user, signed_in

instead of the nice translations i was expecting.

The cause seems to lie in the I18n gem - where it gets the configuration object

class << self
# Gets I18n configuration object.
def config
Thread.current[:i18n_config] ||= I18n::Config.new

I patched this by dropping a file in the lib directory and requiring it from application.rb

module I18n
class << self
def config
# don't pick up the config object from the current thread -
# it returns 'en'::character varying

My guess is that this might slow things down a touch - creating a new config object instead of using an existing one - but it works for me so far

Sunday, 4 January 2009

rcov bugs

There is a really irritating bug in the ruby bindings for Rcov that has been reported by Brian Candler here among other places. Applying Brian's patches solves part of the problem (I think they are now in trunk) but the problem that throws up the error
/usr/local/lib/ruby/1.8/rexml/formatters/pretty.rb:131:in `[]': no
implicit conversion from nil to integer (TypeError)

mentioned later in the post is more annoying - not least because it came back after I already got rid of it once! I have a hunch that this error can be triggered by the content of the html being generated by rcov, and in my case it was triggered by a test requiring a missing file. At first I didn't realise this was the problem of course, and the trace didn't give me a clue about which test caused the problem. The proximate cause lies in a method called wrap in /usr/local/lib/ruby/1.8/rexml/formatters/pretty.rb.

After messing around for a bit i found I that changing the wrap method to return just a string worked fine

def wrap(string, width)
# Recursively wrap string at width.
return string


This gave me an error that identified that culprit test. I could then fix the path to the missing file, change pretty.rb back to the original version, and carry on ...