Cutting Edge Meltdown

Grails, spring-ws, SOAP & HTTP request's content type

2011-06-09T20:39:00.001-07:00

If you ever have to use Grails to process a fucked up SOAP request with a content type of application/x-www-form-urlencoded then this post is for you.

p.s. eventually we will stop processing that kind of requests but for now we need it to work so client has time to fix their shit up

Problem with application/x-www-form-urlencoded requests & spring-ws' message factory is that it does not like requests with that content type. Rightly so!

The message factory content type issue is obvious since the exception that it throws at you is pretty self-explanatory. The work-around is pretty easy, define your own messageFactory spring bean that is more lenient on the content type.

But after the content type is sorted you would face the second problem "Premature end of file". It took me a while to figure out what is happening. In retrospect it is actually quite logical. The end of file is referring to the request's input stream which has been consumed by Grails filters before it gets to the message factory. The following filters are responsible for parsing the request and routing, luckily they are also subclasses of OncePerRequestFilter which means you can easily bypass them to avoid input stream been consumed.

grailsWebRequest
urlMapping
hiddenHttpMethod

How to use Groovy categories in gsp's

2011-06-09T16:58:00.001-07:00

You use Groovy categories in a canonical way in gsp's. i.e. by surrounding all your gsp code inside a call to

<% use(YourCategoryClass) { %>

<% } %>

But it gets troublesome quite soon, especially if the main gsp renders other partial templates.

Luckily there is a way to hook into the view rendering workflow. The trick is to provide your own implementation of View that invoke the call to use categories around the view.render method. To do that you also need to override the default jspViewResolver spring bean with your own implementation of ViewResolver which uses your own implementation of View. Lastly if you need dynamically decide what categories classes to use then you can pass it in the model attribute inside your controller.

The result will look something like this.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

class MyGrailsViewResolver extends GrailsViewResolver {

    @Override
    protected View loadView(String viewName, Locale locale) {
        new MyView(super.loadView(viewName, locale))
    }

    static class MyView implements View {
        def View view

        MyView(View view) {
            this.view = view
        }

        String getContentType() {
            view.getContentType()
        }

        void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) {
            if (model.categories) {
                use(model.remove('categories')) {
                    view.render model, request, response
                }
            } else {
                view.render model, request, response
            }
        }
    }
}

Convert GPathResult to String without tag0

2010-11-25T21:27:00.001-08:00

In Groovy, you can use groovy.xml.XmlUtil.serialize(GPathResult node)
to convert node to XML String.

But sometimes the XML you end up with contains tag0 namespace all over
the elements. It happens because the doc contains default namespace
with empty prefix, so groovy uses a default prefix which is "tag0".
The XML is still correct but it would be nice to not have to see that
crap. To do so you need to create a new closure with the node and
explicitly declare an empty string namespace. Then use
StreamingMarkupBuilder to convert the newly created closure to String.
The following code is how you would implement that logic.

Overwrite Inploy app servers' restart command

2010-07-08T02:57:00.001-07:00

Inploy (http://github.com/dcrec1/inploy) is a rails deployment
solution. It comes with integration to restart 4 app servers:
* mongrel
* passenger
* thin
* unicorn

I needed a way to change how Inploy restarts passenger since our
passenger's restart file is at a different location.

I could've changed the command inside Inploy's passenger.rb but I
wanted to avoid that as there's good chance that someone in the future
won't know to re-apply the change when they upgrade Inploy.

So I needed a way to monkey patch Inploy's passenger module. My first
attempt was to create my version of the Passenger module and require
the file in rails' environment.rb. That was no good because Inploy's
update command does not seem to bootstrap the whole rails environment
so my override simply wasn't getting loaded.

I had to find another way in to load my module for the deployment
process. It turns out the solution I was looking for is in rake. Since
Inploy's update is just a rake task, I could create a passenger.rake
in Rails.root/lib/tasks and define my restart_server override inside
my custom passenger.rake.

Please let me know if there is a better / proper way to achieve what I
needed. Otherwise hope this helps someone else.

My shortcut to open any gem in TextMate with 1 command

2009-12-09T17:42:00.001-08:00

Using the implementation from @peepcode's blog on shell method missing as a base.

I've added another action (code snippet below) to open a gem library in TextMate by typing in the name of the gem followed by ".mate".

when /^[A-Za-z0-9_\-\/]+\.mate$/

# Open the gem in textmate

# @example

# haml.mate

gem_to_open = command.first.gsub(/\.mate$/, '')

run "gem which #{gem_to_open} | tail -1 | xargs dirname | sed -e's/$/\\/../' | xargs mate"

Download sources jar from maven

2009-11-25T22:05:00.001-08:00

We use Maven, when Maven downloads dependencies it doesn't download sources, which I rely on when learn and debug programs....
I was expecting, for what seem a simple thing to me, a flag that I can add in maven's settings files or an option to pass to mvn command.... but I couldn't find the solution (or anything close to it). Don't get me wrong, there are solutions out there, but I just feel it is too much hassle for the task.

So I wrote a little script that go thru my repo and downloads any jar that doesn't have its respective sources :p

ImageMagick and JPEG on OSX

2009-11-23T16:51:00.001-08:00

I am not a fan of port or fink so I always install ImageMagick from source.

Recently I came across a problem where ImageMagick fails to identify JPEG's.

The error looks something like this

identify: no decode delegate for this image format

After some digging around it appears I need to install libjpeg and reinstall ImageMagick for JPEG support.

So I downloaded jpegsrc.v7.tar.gz and just run thru the standard configure, make & make install then reinstalled ImageMagick.

After the installation you should be able to see JPEG as one of the supported format via the command "identify -list format".

It should contain something like this.

JPEG* JPEG rw- Joint Photographic Experts Group JFIF format (70)

Mass erb to haml conversion

2009-09-08T03:19:00.000-07:00

Do this in your application's root folder.

find . -name "*.erb" | while read f; do html2haml -r $f ${f%.erb}.haml; done;

How to stop unix read command escape backslashes

2009-08-27T18:29:00.000-07:00

If you want to pipe any output that has backslashes in it (or make 'read' take a string with backslashes) to the read command then you will need to stop the read command treating backslash as escape character by using read -r
e.g.

cleartool ls | while read -r file
do
  # do something to file
done

Software design or code design

2009-08-24T18:10:00.000-07:00

Software design

Generally high level, a.k.a.

architecture
infrastructure
e.g. 3-tiers or client server, ejb or not

Code design

domain design
flow design
good code design means clean, maintainable code
code design issues are easier to fix than software design

The following extract from Domain Driven Design applies regardless the type of project (waterfall or agile).

Any technical person contributing to the model must spend some
time touching the code, whatever primary role he or she plays on
the project. Anyone responsible for changing code must learn to
express a model through the code. Every developer must be
involved in some level of discussion about the model and have
contact with domain experts. Those who contribute in different
ways must consciously engage those who touch the code in a
dynamic exchange of model ideas through the Ubiquitous
Language.

A solution consultant should touch the code (or at least know the code if they don't want to touch it).

Rails Rumble after thoughts

2009-08-24T17:03:00.000-07:00

Building an application in 48 hrs is hard. Time flies when you are not prepared.

Here are some of the things that you want to touch on before the competition starts.

application security / access - who has access to what
model / resource routes - what models are required and how are they connected from browser / UI perspective
fields & columns in models
model validation / mandatory fields

For the initial first few models that you add to the application, the effort to add each one does not increases in linear fashion.

Because with each model, you need CRUD pages / functionality. Each additional page needs to be styled therefore more visual design required, also more thoughts required for workflow / navigation design.

Often we have to just implement some crude pages to test / visualise our app (particular for workflow) while our designer work thru the markup, which means we usually have to go back and cleanup those pages' markup to fit with the design.

Overall, it was exhausting but I learnt heaps of cool tricks this year building TechMeets.com.

Using google_ajax_library when offline.

2009-08-17T20:01:00.000-07:00

As I mentioned in How do I automatically revert to local javascript when offline?, I eventually forked google_ajax_library gem and added support for working offline.

I sent a pull request to Ryan Heath, the original author the gem and he liked the feature but implemented it slightly differently to what I have done.

How to use WinMerge as ClearCase compare & merge tool?

2009-08-17T19:52:00.000-07:00

WinMerge made ClearCase much more bearable to work with.

When installing WinMerge make sure you tick the 'Integrate with ClearCase' option.

That will make ClearCase use WinMerge as the compare program but ClearCase still uses its own merge program when resolving conflicts.

To change that setting you have to modify ClearCase configuration file manually.

The configuration file is usually in the lib managers' folder of the ClearCase installation.

e.g. C:\Program Files\Rational\ClearCase\lib\mgrs\map

The change to the map file is based on what WinMerge did to the xcompare value

;text_file_delta xmerge ..\..\bin\cleardiffmrg.exe

text_file_delta xmerge C:\work\tools\WinMerge\WinMergeU.exe

How to validate money amount in ActiveRecord?

2009-08-04T05:21:00.001-07:00

This is how I validate money amount in Romey.

Basically an regex that allows up to 2 decimal points or whole integers.

validates_format_of :amount, :with => /^\d+$|^\d+\.\d\d?$/

How I installed ruby and run RoR on QNAP TS-219

2009-04-29T03:13:00.001-07:00

Set LD_LIBRARY_PATH to be /opt/lib so libssl.so.0.9.8 and libcrypto.so.0.9.8 can be found. Alternatively symlink them to /usr/lib might work as well.

Install ruby & rubygems from source, using default options.

Then run this to install mysql gem.

gem install mysql -- --with-mysql-dir=/usr/local/mysql

How do I automatically revert to local javascript when offline?

2009-02-19T19:44:00.001-08:00

I work on Rails applications that include jquery javascript files from ajax.googleapis.com. Every now and then I have to work on those apps offline.

e.g. when I commute on trains.

The application has the same jquery javascript files locally so the old way of working offline was to comment out the google jquery include calls and uncomment the local javascript include calls.

I decided I didn't want to have to bother with that so I implemented something that will check if I am connected online or not and make the appropriate javascript include calls.

The code looks like this:


- if Ping.pingecho("ajax.googleapis.com", 10, 80)
  = google_jquery
- else
  = javascript_include_tag 'jquery-1.2.6.min.js'

The added bonus is that if ever ajax.googleapis.com goes down then our apps won't be affected.

p.s. the above code is markup in haml and uses google_ajax_libraries_api plugin and ping.rb which comes with standard ruby installation. Down the track I might modify the plugin to support the offline backup.

How to remove windows carriage return (^M) on Mac

2009-01-12T20:14:00.001-08:00

I don't want to install dos2unix via port and I know it's just a matter of search and replace those ^M chars.

Here are a couple of command that should do the job of removing those trailing ^M (carriage return) chars.

perl -pi -e's/\r//g' filename
sed -e's/^M//g' filename > newfile

To type ^M in Terminal do Ctrl+V then Ctrl+M.

Use ActiveRecord migration to manage database changes in Java projects

2009-01-09T22:02:00.001-08:00

A sort of sequel to dumping schema into ruby. I am going to show how we can use ActiveRecord migration to manage our database change in Java projects.

Problem:

Automatically track which schema change has been made to a database.
Make it easy to recreate another database with the same schema.

Requirements:

bsf.jar (from jruby binary download)

jruby-complete jar

jdbc jar

activerecord gem
activerecord-jdbc-adapter gem

Resources:
http://www.ics.muni.cz/~makub/ruby/#c2

Steps:

install jruby

jruby -S gem install --no-rdoc --no-ri activerecord
jruby -S gem install --no-rdoc --no-ri activerecord-jdbc-adapter

See some code at http://github.com/shenie/base_java_project/tree/master

Known issues:

The jruby-complete jar contains rubygems and you can package up the other gems (above) into the jruby-complete jar and distribute it (check it into vcs) that way.

http://www.nabble.com/Packaging-up-gems-with-jruby-complete-td21188167.html

Another way is to set GEM_PATH env variable to the location of the jruby gem directory.

e.g. /Users/andy/dev/tools/jruby/lib/ruby/gems/1.8

http://www.ruby-forum.com/topic/163251

At the moment, you need to set GEM_PATH to be the jruby gem directory, which means each machine will require jruby to be installed plus the gems used.

It would be more ideal if we can just repackage jruby-complete jar with the additional gems to make deployment easier.

Update: Thanks to Nick's blog, you no longer have to set GEM_PATH to get the gems required included by the base application.

How to do mass renaming of file extension

2009-01-09T03:20:00.000-08:00

Problem:
You want to rename all the .wiki files to be .textile instead.

Solution:
\ls -1 *.wiki | while read f; do mv $f ${f%.wiki}.textile; done

Easy way to backup codebase on USB key with git

2009-01-09T03:16:00.001-08:00

Requirements:

git (via cygwin)
$ git --version
git version 1.6.0.4

On USB key
mkdir project.init and cd into it
git --bare init

In project codebase's directory
git init
git add .
git ci -m'first commit'
git remote add origin /path/to/project.git
git push origin master

Modify you local master to track remote by appending the following to your project's .git/config file:

[branch "master"]
remote = origin
merge = refs/heads/master

Then you can just do the following in the future to push new files to your USB.
git add .
git ci -m'update repos'
git push

Gotchas when using git on cygwin

$ git push origin master
Counting objects: 6669, done.
Compressing objects: 100% (6570/6570), done.
Writing objects: 100% (6669/6669), 7.90 MiB | 348 KiB/s, done.
Total 6669 (delta 4488), reused 0 (delta 0)
*** Project description file hasn't been set
error: hooks/update exited with error code 1
error: hook declined to update refs/heads/master
To /cygdrive/e/westpac/compass.git
! [remote rejected] master -> master (hook declined)
error: failed to push some refs to '/cygdrive/e/project.git'

The above problem is caused by a hook script (.git/hooks/update).
Rename update to something like update.bak so it does not get executed solves the above problem.

p.s. with the newer version of cygwin git the hook scripts are all suffixed with .sample in the file name, which means they don't get executed hence won't have the above problem.

Use jruby to dump DB schema to ruby

2009-01-09T02:05:00.001-08:00

Problem:

I have a database that rails doesn't have an easy way to connect to.

Solution:

Use jruby & JDBC

Requirements:

jruby

activerecord

activerecord-jdbc-adapter

jdbc driver for the database you want to connect to

Resources:

http://jruby-extras.rubyforge.org/activerecord-jdbc-adapter/

Steps:

jruby -S gem install activerecord
jruby -S gem install activerecord-jdbc-adapter

Put the jdbc jar in Classpath for jruby. e.g. inside C:\work\tools\jruby-1.1.6\lib

Run this script:

require 'rubygems'
gem 'activerecord-jdbc-adapter'
require 'jdbc_adapter'
require 'active_record'

ActiveRecord::Base.establish_connection(
:adapter => 'jdbc',
:driver => 'com.microsoft.sqlserver.jdbc.SQLServerDriver',
:url => 'jdbc:sqlserver://localhost:1433;DatabaseName=FineosSixApp',
:username => 'username',
:password => 'password'
)

ActiveRecord::SchemaDumper.dump

To load the schema into say mysql
require 'rubygems'
require 'active_record'

ActiveRecord::Base.establish_connection(
:adapter => "mysql",
:host => "localhost",
:username => 'username',
:password => 'password',
:database => 'database'
)

load('schema.rb')

Future Improvements:

Instead of using jruby on command line, create an ant task that uses jruby.jar and do the same thing.
Basically integrating the schema dump into the build file.

It'll be useful to store the client code base along with schema that runs with the code base.

How to copy gems to a different ruby installation

2007-09-25T04:19:00.000-07:00

Assume the following:
old ruby 1.8.4 installed in /opt/local/lib/ruby
new ruby 1.8.6 installed in /usr/local/lib/ruby


cd /opt/local/lib/ruby
sudo cp -r gems /usr/local/lib/ruby
cd site_ruby/1.8/
sudo cp -r gemconfigure.rb rubygems rubygems.rb ubygems.rb rbconfig /usr/local/lib/ruby/site_ruby/1.8/

cd /opt/local/bin
sudo rm irb gem ruby rake
sudo rm erb gem_mirror gem_server gemwhich generate_yaml_index.rb rails rdoc ri testrb update_rubygems

restart terminal

this is for emergency cos you should really re-install ruby related things since we might not have moved everything

done

What blogging app should I user?

2007-09-23T05:13:00.000-07:00

Word press seems like a better application for my need...

2009 Update: after discovering google document's publishing feature I've decided to use blogger.com

Muhahahaha I'm back

2007-02-02T16:51:00.000-08:00

The loser that hi-jacked my blog address (after I deleted it) for advertising is gone so I decided to take blog back so it can't be used to do evil things :)