Dave Perrett

Nested for_each with Terraform

hello@daveperrett.com (Dave Perrett) — Thu, 19 Aug 2021 00:00:00 +0000

Terraform provides a for_each iterator which allows you to loop over elements of a list, and perform an operation with each element. For example, to grant multiple permissions for myself on a Snowflake schema, I could do something like this: resource "snowflake_schema_grant" "write_permissions" { for_each = toset(["CREATE TABLE", "CREATE VIEW", "USAGE"]) database_name = "MY_DATABASE" privilege = each.key roles = "DAVE" schema_name = "MY_SCHEMA" } This loops over each element in the for_each list, and substitutes it as the privilege using each.

Working with local Terraform providers

hello@daveperrett.com (Dave Perrett) — Thu, 19 Aug 2021 00:00:00 +0000

I recently submitted a small fix to @chronark’s Vercel provider. The fix itself was pretty trivial, but it took me quite a while to figure out how to actually run Terraform against a local copy of the provider in order to make sure it actually worked. I found the answer eventually in the Terraform CLI documentation. As a convenience for provider development, Terraform supports a special additional block dev_overrides in provider_installation blocks.

An update to exif-orientation-examples

hello@daveperrett.com (Dave Perrett) — Sat, 05 Aug 2017 00:00:00 +0000

I was surprised to discover recently that my exif-orientation-examples repository has quietly collected almost 300 stars on github. The sample images were created over 5 years ago now, and are pretty low-resolution and unsuitable for testing on modern displays and websites.

With that in mind, I’ve replaced the sample images with 1200x1800 pixel images (previously they were 600x450 pixels), and automated the process of generating new images.

Importing a Pivotal Tracker project into Trello

hello@daveperrett.com (Dave Perrett) — Mon, 13 Jan 2014 00:00:00 +0000

I’m currently in the middle of migrating a project from Pivotal Tracker to Trello, and couldn’t find any easy method of importing the data, so I spent this morning putting together a gem to do exactly that.

Callback support and a version bump for jquery-simple-color

hello@daveperrett.com (Dave Perrett) — Mon, 08 Apr 2013 00:00:00 +0000

The jquery-simple-color plugin has received a bunch of callback-related goodness thanks to jbergen. He’s also added a live preview option which displays the currently-hovered-on color.

Recreating the Reeder two-tone horizontal rule in pure CSS

hello@daveperrett.com (Dave Perrett) — Sun, 07 Apr 2013 00:00:00 +0000

I’m a huge fan of the design of Reeder, and wanted to take a stab at recreating their fading two-tone horizontal rule in CSS for this blog.

Sending mail with SendGrid on Ubuntu

hello@daveperrett.com (Dave Perrett) — Tue, 19 Mar 2013 00:00:00 +0000

I keep forgetting how to do this, so purely for my own benefit - how to set up Ubuntu to send via sendmail and SendGrid.

A bit of digital house cleaning

hello@daveperrett.com (Dave Perrett) — Mon, 18 Mar 2013 00:00:00 +0000

My old recursive-design.com site has served me well for a couple of years of contracting and consulting, but having jumped headfirst into a startup, my focus is now on reducing my workload rather than increasing it :)

EXIF orientation handling is a ghetto

hello@daveperrett.com (Dave Perrett) — Sat, 28 Jul 2012 00:00:00 +0000

One of my favourite services at the moment is Transloadit, who provide an image processing API that works a treat on top of platforms like Heroku, where there are strict request timeout limits that make large uploads difficult. They handle auto-orientation of images automagically by default, and normally I’m not even aware of it happening during testing since my camera and OSX also handle auto-orientation transparently.

Messing around with ruby-processing, take 5

hello@daveperrett.com (Dave Perrett) — Thu, 31 May 2012 00:00:00 +0000

I’ve been spending quite a bit of time playing with ruby-processing (and processing in general) recently. It’s also been my first exposure to JRuby which has been a bit of an eye-opener, in terms of the sheer number of Java libraries that it makes available in Ruby.

All the fun stuff in processing seems to be OpenGL-related, and after a lot of research the easiest way to dig in ended up being the GLGraphics Java library, which was made specifically for use in processing.

Underscores are stupid? Get a Japanese keyboard

hello@daveperrett.com (Dave Perrett) — Wed, 16 May 2012 00:00:00 +0000

There was a surprising amount of discussion on Hacker News today on whether or not underscores are stupid, with suggestions ranging from changing key bindings to using the Dvorak layout.

Here’s an alternative (although possibly slightly drastic) solution - get a Japanese keyboard:

Back from blogging hiatus

hello@daveperrett.com (Dave Perrett) — Mon, 14 May 2012 00:00:00 +0000

The last year has been a bit of a whirlwind, and saw Emi and I leave Tokyo, travel Asia, Russia and Europe for a couple of months, spend some time back in Australia catching up with family, and eventually take up an offer we couldn’t refuse to co-found a startup in Christchurch, New Zealand.

Hiding ruby gem 'is deprecated with no replacement' messages

hello@daveperrett.com (Dave Perrett) — Sat, 21 May 2011 00:00:00 +0000

I recently installed ruby 1.9.2 via rvm, and suddenly every command started spitting out hundreds of line of deprecation messages :

'405 Not Allowed' error serving Facebook apps with nginx

hello@daveperrett.com (Dave Perrett) — Fri, 20 May 2011 00:00:00 +0000

I’ve spent the last couple of evenings playing around with some Hello World-type stuff for Facebook app development in preparation for an up-coming Facebook/Rails gig.

After creating a new app on Facebook, you are presented with the code for a basic starter-page for the app:

Continuous integration for PHP with phpUnderControl

hello@daveperrett.com (Dave Perrett) — Fri, 13 May 2011 00:00:00 +0000

Whenever I start a new PHP project for a client, one of the first things I set up is usually phpUnderControl - a CI (continuous integration) server specifically for PHP built on top of CruiseControl.

Time Out In NZ

hello@daveperrett.com (Dave Perrett) — Wed, 04 May 2011 00:00:00 +0000

I’ve been flat out with a couple of contracting projects recently - apologies for the four-month blogging hiatus!

One of these projects (albeit a quickie) was a weekend spent making a rails site for a couple of New Zealand organizations to help the victims of the Japanese quakes and tsunami relocate themselves and/or their children to New Zealand temporarily.

A Christmas present from The Echo Nest

hello@daveperrett.com (Dave Perrett) — Wed, 05 Jan 2011 00:00:00 +0000

A couple of weeks before Christmas I got a mail from The Echo Nest developer team promising a free T-shirt for filling out a survey :

Simple video remixes using The Echo Nest API

hello@daveperrett.com (Dave Perrett) — Wed, 05 Jan 2011 00:00:00 +0000

Here’s a couple of remix videos I did earlier in the year using The Echo Nest API.

I’ve been meaning to post these for a while, but finally decided to get off my ass and put them up since the folks at Echo Nest were kind enough to send me a T-shirt :

Face detection with OSX and python

hello@daveperrett.com (Dave Perrett) — Tue, 14 Dec 2010 00:00:00 +0000

I’ve been messing about with face detection for a while, and was surprised how easy it is to get basic detection working out-of-the-box with open-source libraries.

Today we’ll look at a simple way to get started with face detection on OSX using python.

Jekyll plugins for categories, projects and sitemaps

hello@daveperrett.com (Dave Perrett) — Wed, 08 Dec 2010 00:00:00 +0000

2013-03-28 Update : These plugins are now hosted on GitHub

I’ve finally gotten around to cleaning up and releasing the source for a couple of the Jekyll plugins used to build this site.

You can find them all on the Jekyll Plugins project page, or browse the source.

As always, if you come across any problems please create a ticket and we’ll try to get it fixed as soon as possible.

Enjoy!

CompSci 101 - Big-O notation

hello@daveperrett.com (Dave Perrett) — Tue, 07 Dec 2010 00:00:00 +0000

I recently had a couple of Google interviews in Tokyo, and while preparing for them I ended up with a huge list of things I wanted to brush up on before the interview.

It turns out I didn’t get the job (next time!), but I thought I might be able to learn something anyway by working through the list and blogging about the main areas that companies like Google expect you to know.

Without further ado, first on the list is Big-O notation:

jQuery SimpleColor plugin hits version 1.0

hello@daveperrett.com (Dave Perrett) — Tue, 07 Dec 2010 00:00:00 +0000

A couple of weeks ago someone commented on the SimpleColor plugin with a nice suggestion - adding the selected color as text inside the color selection button. I finally got around to implementing this last night, and added a couple of extra options to support this :

A weekend project - fromthecache.com

hello@daveperrett.com (Dave Perrett) — Wed, 03 Nov 2010 00:00:00 +0000

I was playing around on the weekend screen-scraping and analyzing word-frequencies for various sites (don’t ask), and was getting some slow responses (and accidentally got my IP blocked from one site when I hit them a few too many times).

Eventually I hit upon the idea of hitting Google Cache for each URL (the pages I was scraping had sequential ?id=xxx URLs so it was easy to automate), with the aim of speeding things up a bit and taking some load off the target sites.

With this in mind, I spent a few hours Saturday and Sunday developing fromthecache.com - it’s built on rails, and designed to provide transparent access to the Google cache, while fetching the original page as a fallback if necessary.

Introducing Rails Kitchen Sink

hello@daveperrett.com (Dave Perrett) — Thu, 21 Oct 2010 00:00:00 +0000

2013-03-28 Update : This project is very dated, and I don’t recommend it’s use. It’s now hosted on GitHub.

I’m happy to announce the release of Rails Kitchen Sink a rails-project-starter, which I’ll be building all future Rails apps off of.

Static blogging the Jekyll way

hello@daveperrett.com (Dave Perrett) — Tue, 12 Oct 2010 00:00:00 +0000

In building the new site, I decided to take the opportunity to try out something new. I’ve been using WordPress to power my blog for about 5 years, and while it has served me well, I wanted to try out something different. The main criteria for choosing a new blogging platform were :

It should serve true static pages, with no need for server-side processing.
It should be easy to store the entire site in Git.
It should support the concept of layouts - I wanted to have a single ’template’ file that blog posts could easily inherit from.
It should support MarkDown or Textile for formatting posts, since I want to keep away from posting raw HTML as much as possible.
It should support comments.
I should be able to deploy updates to the site with a single command.

By patching together a few different open-source technologies, I’ve been able to achieve the above and more.

Excluding fields from rails json and xml output

hello@daveperrett.com (Dave Perrett) — Sun, 03 Oct 2010 00:00:00 +0000

Rails has a very handy ‘respond_to’ feature to render your pages in different formats :

respond_to do |format|
  format.json { render :json => @user }
  format.xml  { render :xml => @user }
  format.html
end

However, by default it outputs every field in the model, which exposes some data (encrypted-password and password-salt) that I’d rather keep to myself :

HABTM before_filter in rails models

hello@daveperrett.com (Dave Perrett) — Sun, 03 Oct 2010 00:00:00 +0000

I’ve been playing about with Devise and CanCan for rails authentication and authorization recently - this great pair of posts from Tony Amoyal have helped a great deal.

I have a User model and a Role model, and wanted to automatically add the :user role to each user whenever roles are assigned. The roles were set in the controller as follows:

How to create a TextMate bundle

hello@daveperrett.com (Dave Perrett) — Thu, 30 Sep 2010 00:00:00 +0000

If you find yourself repeating the same commands over and over in TextMate, it’s relatively straightforward to create your own bundle. Recently I’ve been migrating a bunch of blog posts from WordPress to Jekyll, and found myself repeating the same tasks again and again :

New 'projects' section launched

hello@daveperrett.com (Dave Perrett) — Wed, 29 Sep 2010 00:00:00 +0000

2013-03-28 Update : All projects are now hosted on GitHub

I’m pleased to announce my new projects section, where I’ll be consolidating the various open-source projects I’ve released.

Until now these projects have usually only been released via blog posts, but from now on each project will have a dedicated project page, with git repository information, issue tracking, and a link to a downloadable zip bundle of the latest release.

Security testing with Google's ratproxy

hello@daveperrett.com (Dave Perrett) — Fri, 24 Sep 2010 00:00:00 +0000

Ratproxy is a passive web application security assessment tool released by Google. Basically you set it up as a proxy server between yourself and the target site, and then click around in the target site doing whatever it is you normally do, while ratproxy analyzes your activity in the background and looks for security holes.

recurser.com has a new home - update your feeds please!

hello@daveperrett.com (Dave Perrett) — Thu, 23 Sep 2010 00:00:00 +0000

All of the content from recurser.com (blog posts, static pages, code repositories, git/svn etc) has been migrated over to the main “recursive-design.com”:/ site. If you’re reading this from the old recurser.com RSS feed, please update the feed address - sorry for the inconvenience! You can find the new feed at recursive-design.com/feed/ . The old feed will continue for a few weeks, but will eventually be turned off. I’m planning on posting a lot more regularly from now on, so if you aren’t a subscriber yet now would be a great time to start !

Integrating Jekyll with FeedBurner

hello@daveperrett.com (Dave Perrett) — Tue, 14 Sep 2010 00:00:00 +0000

It’s relatively easy to get the feed for your Jekyll site running on FeedBurner.

Firstly, you need to choose a subdirectory to host your feed on. Calling it feed seems to be a fairly popular choice, so I decided to follow the crowd. Create a folder called feed at the base of your Jekyll site, and create an index.xml file inside with the following contents (obviously swapping the references to Recursive for your own site details) :

SSH Authentication refused: bad ownership or modes for directory

hello@daveperrett.com (Dave Perrett) — Tue, 14 Sep 2010 00:00:00 +0000

I just spent 30 minutes trying to get login via public key working on a new server, and here’s a few tips that I wish I knew earlier :

New site launched!

hello@daveperrett.com (Dave Perrett) — Mon, 13 Sep 2010 00:00:00 +0000

Today I’m very happy to announce the launch of my new site Previously my open-source code, company information and blog posts had been spread over several different sites. All this various content will be consolidated into a single site here over the next couple of months, which will hopefully allow me to focus more on doing what I love - building beautiful apps, and hacking on open-source code. I’m also hoping to set a regular blogging schedule, so stay tuned for more posts and announcements!

Push and delete remote git branches

hello@daveperrett.com (Dave Perrett) — Wed, 17 Mar 2010 00:00:00 +0000

This is easy to do, but I always forget how to do it, so this is more a reminder to myself than anything else.

To create and checkout a branch in git :

Compiling and running red5 flash server on OSX

hello@daveperrett.com (Dave Perrett) — Tue, 16 Mar 2010 00:00:00 +0000

First, you need to make sure you are using java 1.6. I’m told this method will only work on 64-bit leopard machines, so your mileage may vary. In the finder, browse to /Applications/Utilities and open Java Preferences.app .

Compiling Nginx with flv streaming support on Ubuntu

hello@daveperrett.com (Dave Perrett) — Tue, 16 Mar 2010 00:00:00 +0000

First, we need to get the latest version of nginx :

> wget http://nginx.org/download/nginx-0.8.34.tar.gz
> tar xvzf nginx-0.8.34.tar.gz
> cd nginx-0.8.34

Next, configure it to support ssl, gzip, flv streaming and real-ip. I generally compile it to /opt/nginx-YYMMDD (change the –prefix setting if you want to put it somewhere else) :

Installing Flex 4 (Gumbo) SDK on OS X

hello@daveperrett.com (Dave Perrett) — Sun, 14 Mar 2010 00:00:00 +0000

How to find out if Ubuntu is 32 bit or 64 bit

hello@daveperrett.com (Dave Perrett) — Sat, 06 Mar 2010 00:00:00 +0000

To find out if Ubuntu is 32 bit or 64 bit, run uname : uname -m x86_64 = 64 bit i686 = 32 bit

sources.list For Ubuntu Hardy Heron 8.04

hello@daveperrett.com (Dave Perrett) — Sat, 06 Mar 2010 00:00:00 +0000

I keep having to look this up to add multiverse repositories (courtesy of tuxicity).

Installing git-up on Ubuntu 8.10

hello@daveperrett.com (Dave Perrett) — Sun, 14 Feb 2010 00:00:00 +0000

Recently I had a bit of trouble getting {{ “github.com/aanand/git-up” | ext_link: “git-up”}} to work on Ubuntu (or anywhere else for that matter), so here’s some of the steps I had to go through.

Initially ubuntu seems to have RubyGems 1.01 and 1.2.0 installed :

> gem --version
1.2.0
>/usr/bin/gem1.8 --version
1.2.0
>/usr/bin/gem1.9 --version
1.0.1

Updating RubyGems on Mac OS X 10.5 Leopard

hello@daveperrett.com (Dave Perrett) — Sun, 14 Feb 2010 00:00:00 +0000

I haven’t used ruby for a while, but recently wanted to try out {{ “github.com/aanand/git-up” | ext_link: “git-up”}} on OSX. According to the {{ “github.com/aanand/git-up/blob/master/README.md” | ext_link: “instructions”}}, a simple gem install git-up should work :

> sudo gem install git-up
Updating metadata for 1 gems from http://gems.rubyforge.org
.
complete
ERROR:  could not find git-up locally or in a repository

I assume this is something to do with gem hosting moving to github or something… I haven’t really been following ruby for a year or so so I’m not sure exactly what’s going on. It seems i’m running a pretty old version of RubyGems, so I tried to update :

nginx error - 413 Request Entity Too Large

hello@daveperrett.com (Dave Perrett) — Wed, 18 Nov 2009 00:00:00 +0000

If you’re getting 413 Request Entity Too Large errors trying to upload with {{ “nginx.net/” | ext_link: “Nginx”}}, you need to increase the size limit in nginx.conf . Add ‘client_max_body_size xxM’ inside the server section, where xx is the size (in megabytes) that you want to allow. http { include mime.types; default_type application/octet-stream; sendfile on; keepalive_timeout 65; server { client_max_body_size 20M; listen 80; server_name localhost; # Main location location / { proxy_pass http://127.

Makefile - missing separator. Stop.

hello@daveperrett.com (Dave Perrett) — Thu, 12 Nov 2009 00:00:00 +0000

If you’re getting missing separator errors in your makefile, similar to the following : Makefile:22: *** missing separator. Stop. … make sure you are using real tabs instead of spaces. A global search and replace for four-spaces should fix things up.

NoReverseMatch : custom registration templates break django unit tests

hello@daveperrett.com (Dave Perrett) — Tue, 10 Nov 2009 00:00:00 +0000

I’ve over-ridden several of the built-in django auth and {{ “bitbucket.org/ubernostrum/django-registration/” | ext_link: “django-registration”}} templates so I can have my own custom-styled login and registration pages. This all worked fine until i tried to run the built-in django and django_registration test suites, when everything fell apart :

Sending Django email with Gmail

hello@daveperrett.com (Dave Perrett) — Fri, 16 Oct 2009 00:00:00 +0000

After spending a few hours struggling to get postfix to work with django on my local dev machine, I gave up and decided to use Gmail . To do it, add the following to your settings.py :

Compiling mysql-python on OS X leopard

hello@daveperrett.com (Dave Perrett) — Tue, 18 Aug 2009 00:00:00 +0000

I’ve just finished trying to install mysql-python on OSX Leopard, and had quite a few problems. This is the procedure that finally ended up working for me.

First, download mysql-python from here. Unzip and try to build it :

'Hello World' with Scala and Lift on OSX

hello@daveperrett.com (Dave Perrett) — Mon, 17 Aug 2009 00:00:00 +0000

Obviously we’re going to need scala before we can do anything useful; the easiest way to install it is via macports . We’re also going to need maven.

> sudo port install scala
> sudo port install maven2

Scala seems to have moved their repository to github, and the old google code repository no longer works. Assuming you have git installed (if not, there’s an OS X installer here) :

mysql select random row with join

hello@daveperrett.com (Dave Perrett) — Tue, 11 Aug 2009 00:00:00 +0000

I have a users table and an assets (basically just images) table, and I want to select and display a random asset for each user. I want to show a list of users, with a random thumbnail for each user from their assets.

I could do this easily enough in code with multiple queries, but it seemed like a nice challenge to try and find a pure-sql alternative.

Customize the Nginx server header

hello@daveperrett.com (Dave Perrett) — Mon, 10 Aug 2009 00:00:00 +0000

Unfortunately the only way to change the server header in nginx is to actually recompile it from source. Luckily this is quite easy.

First, download the latest version of nginx (0.7.61 at the time of writing) :

> wget http://sysoev.ru/nginx/nginx-0.7.61.tar.gz
> tar xvzf nginx-0.7.61.tar.gz
> cd nginx-0.7.61

Passing IPs to apache with nginx proxy

hello@daveperrett.com (Dave Perrett) — Mon, 10 Aug 2009 00:00:00 +0000

When you use nginx to proxy to apache , apache picks up the IP address of your nginx proxy as the client. A consequence of this is that apache log files, and any application running on the apache backend, will all receive the same IP address (for example 127.0.0.1 if apache and nginx are running the same server).

Luckily, nginx provides a HTTP X-Forwarded-For header containing the clients real IP address, although apache doesn’t pick it up by default. To allow apache to recognize the original client IP, we need to install the mod_rpaf module. On ubuntu, this is as simple as installing a package :

InnoDB as default MySQL table type

hello@daveperrett.com (Dave Perrett) — Sun, 09 Aug 2009 00:00:00 +0000

To change the default MySQL table type, edit your my.cnf file (usually /etc/mysql/my.cnf on ubuntu), and add the following line to the [mysqld] section :

 default-table-type=innodb

The resulting config will look something like this :

Flushing the DNS cache on OS X

hello@daveperrett.com (Dave Perrett) — Wed, 05 Aug 2009 00:00:00 +0000

I often find that OS X refuses to obey my /etc/hosts file for some time after I change it. It seems that often you have to manually flush the DNS cache by hand to force host file changes to take effect. Under pre-leopard systems, use lookupd : > sudo lookupd -flushcache Starting with Leopard, lookupd has been replaced with dscacheutil : > sudo dscacheutil -flushcache

MySQL table 'is marked as crashed'

hello@daveperrett.com (Dave Perrett) — Thu, 18 Jun 2009 00:00:00 +0000

I recently had a problem trying to use mysqldump where it was complaining that

mysqldump: Got error: 145: Table './recurser/wp_options' is marked as crashed and should be repaired when using LOCK TABLES

This corrupted wp_options table actually caused wordpress to think it was a fresh install, and showed the interface to create the admin user to anyone who accessed recurser which is a little scary :)

The solution was to go to the actual database directory, and run myisamchk -r on the offending table :

HTTPSHandler error using python 2.5 and GAE on OS X

hello@daveperrett.com (Dave Perrett) — Sat, 06 Jun 2009 00:00:00 +0000

If you are getting an error complaining that ‘module’ object has no attribute ‘HTTPSHandler’ running python 2.5 on OS X :

Python 2.5 "ImportError: No module named _md5" on OS X

hello@daveperrett.com (Dave Perrett) — Sat, 06 Jun 2009 00:00:00 +0000

If you are getting an error complaining about missing md5 running python 2.5 on OS X : Traceback (most recent call last): File "<string>", line 1, in <module> File "/Users/dave/Desktop/setuptools-0.6c9-py2.5.egg/setuptools/command/easy_install.py", line 21, in <module> File "/Users/dave/Desktop/setuptools-0.6c9-py2.5.egg/setuptools/package_index.py", line 2, in <module> File "/opt/local/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/urllib2.py", line 91, in <module> import hashlib File "/opt/local/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/hashlib.py", line 133, in <module> md5 = __get_builtin_constructor('md5') File "/opt/local/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/hashlib.py", line 60, in __get_builtin_constructor import _md5 ImportError: No module named _md5 … you need to install py25-hashlib :

python 2.5 zipimport.ZipImportError on OS X

hello@daveperrett.com (Dave Perrett) — Sat, 06 Jun 2009 00:00:00 +0000

If you are getting an error similar to the following trying to run pythin2.5 on OS X : zipimport.ZipImportError: can't decompress data; zlib not available … you need to install py25-zlib : > sudo port install py25-zlib

Exclude tables from mysqldump

hello@daveperrett.com (Dave Perrett) — Tue, 02 Jun 2009 00:00:00 +0000

Recently I was in a position where i wanted to exclude 2 large tables from mysqldump, without specifying every single table I wanted to back up. After a bit of searching, it seems you can easily exclude tables from mysqldump using the –ignore-table option : > mysqldump -u dave -ppassword -h localhost --ignore-table=my_db_name.my_table_name my_db_name …obviously substituting your own username, password, db name and table name etc . As far as i can tell you can use this option multiple times to exclude multiple tables

'spec/rake/spectask' errors doing rake db:migrate

hello@daveperrett.com (Dave Perrett) — Wed, 29 Apr 2009 00:00:00 +0000

If you get an error similar to the following while running rake db:migrate : error no such file to load -- spec/rake/spectask … you need to install the rspec gem : > sudo gem install rspec

Rename authors in a git repository

hello@daveperrett.com (Dave Perrett) — Wed, 29 Apr 2009 00:00:00 +0000

I recently imported the old Clutch code into git , but for some reason it ignored the authors.txt file I provided, and used the original svn user names.

This info is based largely on this stack overflow post .

First, clone your repository locally :

'Can't find Magick-config' error installing rmagick gem

hello@daveperrett.com (Dave Perrett) — Sun, 26 Apr 2009 00:00:00 +0000

If you are getting the error ‘Can’t find Magick-config’ when installing the RMagick gem, chances are you’re missing the libmagick9-dev library. /opt/ruby-enterprise-1.8.6-20090201/bin/ruby extconf.rb install rmagick checking for Ruby version >= 1.8.2... yes checking for gcc... yes checking for Magick-config... no Can't install RMagick 2.9.1. Can't find Magick-config in ..... To fix this on ubuntu, simply install libmagick : apt-get install libmagick9-dev

undefined method assert_valid_keys in Rails

hello@daveperrett.com (Dave Perrett) — Tue, 24 Feb 2009 00:00:00 +0000

If you are getting an error about ‘undefined method assert_valid_keys’ in Rails :

undefined method `assert_valid_keys' for :time_entry_product:Symbol

… it may be because you have two relationships specified on the same line in your model :

Styling Apache directory listings with mod_autoindex

hello@daveperrett.com (Dave Perrett) — Mon, 29 Dec 2008 00:00:00 +0000

Index-Style is a set of html, css and image files designed to work together with the mod_autoindex module to make the default Apache file listings look a little nicer. The UI design is based almost entirely on the great work done by the guys at Repos-Style, although the code itself is largely done from scratch (as mod_autoindex doesn’t support XSLT).

Nginx adds strange characters using rails/memcached_pass

hello@daveperrett.com (Dave Perrett) — Tue, 23 Dec 2008 00:00:00 +0000

After upgrading a few gems recently, I found that the content returned from the nginx memcached_pass directive always had a few strange characters prepended.

After some investigation it seems that this is caused by rails ‘marshalling’ the data. If you’re using a memcached set command such as

Cache.set(key, content, time_to_live)

You need to add an extra argument to force rails to cache the raw data instead of marshalling it :

Phusion Passenger PassengerMaxPoolSize is ignored

hello@daveperrett.com (Dave Perrett) — Mon, 22 Dec 2008 00:00:00 +0000

I’ve been wondering for a while why Phusion Passenger seems to completely ignore the PassengerMaxPoolSize, PassengerMaxInstancesPerApp and PassengerPoolIdleTime directives. I recently discovered that they don’t work inside VirtualHost blocks in apache config. The old (non-working) config was something like :

Pylons - LookupError: Entry point 'main' not found in egg

hello@daveperrett.com (Dave Perrett) — Sun, 21 Dec 2008 00:00:00 +0000

If you are getting a LookupError in Pylons similar to the following :

memcaches_page plugin for Rails

hello@daveperrett.com (Dave Perrett) — Wed, 03 Dec 2008 00:00:00 +0000

This plugin is very similar to the built-in Rails ‘caches_page’ functionality, except it caches to memcached rather than a file. It relies on the ‘memcached_pass’ nginx directive to serve pages directly from memory if possible, and only passes to rails if necessary. On my server I’ve seen a 75% reduction in Ruby memory usage using this technique.

Gantt Calendar plugin for Trac

hello@daveperrett.com (Dave Perrett) — Wed, 26 Nov 2008 00:00:00 +0000

2013-03-28 Update : This plugin is hosted on GitHub for historical reasons, but no longer supported. Please use the sibuya-trac version.

2010/12/16 Update : I’ve been in touch with the original author of this plugin, and his latest version (0.12) supports English now.

I recommend you use his svn repository rather than this out-dated version :

> svn co http://svn.sourceforge.jp/svnroot/shibuya-trac/plugins/ganttcalendarplugin/trunk ganttcalendarplugin

iTerm Delete Key Config

hello@daveperrett.com (Dave Perrett) — Fri, 24 Oct 2008 00:00:00 +0000

I’ve often found that after SSHing with iTerm, the delete key mappings are occasionally (well regularly) problematic. This post from Alaska Geeks sorted the problem out straight away in my case :

Styling subversion listings with xslt

hello@daveperrett.com (Dave Perrett) — Wed, 17 Sep 2008 00:00:00 +0000

The default Apache mod_dav_svn listings are a little bland, but luckily you can use the SVNIndexXSLT Apache directive to spice things up a bit. I’ve been using a slightly modified version of the fantastic ReposStyle XSLT styles.

Assuming you’ve already set up subversion , download the latest ReposStyle from here and drop it in the document root, and configure Apache something like this :

Rewrite Trac links to Redmine with nginx

hello@daveperrett.com (Dave Perrett) — Thu, 11 Sep 2008 00:00:00 +0000

I recently migrated from Trac (at http://recurser.com/trac/ ) to Redmine (at http://recurser.com/code/ ), and wanted the Trac links to redirect to the right place if possible. The nginx rules that follow achieve most of that. As always, there are a few catches:

Disable store links in iTunes 8

hello@daveperrett.com (Dave Perrett) — Sun, 17 Aug 2008 00:00:00 +0000

The preference to remove these links in iTunes 7 seems to have disappeared in version 8. You can turn them off, however, in the terminal : $ defaults write com.apple.iTunes show-store-arrow-links -bool FALSE Restart iTunes, and the links should be gone.

Filesystem path is neither a file nor a directory 160013 - SVN / Trac Error

hello@daveperrett.com (Dave Perrett) — Sun, 27 Jul 2008 00:00:00 +0000

Recently I had an SVN repository with a couple of corrupt revisions that I couldn’t figure out how to fix, which caused Trac to stop displaying revisions after the corruption.

Trying trac-admin resync was no help, throwing this exception :

Installing Trac on CentOS

hello@daveperrett.com (Dave Perrett) — Sun, 27 Jul 2008 00:00:00 +0000

Before you do anything, go ahead and install subversion .
Install the python easy install tool:

Simulate delayed-fade in jQuery

hello@daveperrett.com (Dave Perrett) — Tue, 15 Jul 2008 00:00:00 +0000

Unfortunately there is no .delay() function in jQuery. You can fake this, however, by using the .fadeTo() function:

$("#my_element").fadeIn(1000).fadeTo(5000, 1).fadeOut(1000);

svn: Can't find a temporary directory: Internal error

hello@daveperrett.com (Dave Perrett) — Mon, 14 Jul 2008 00:00:00 +0000

If you’re getting a ‘svn: Can’t find a temporary directory: Internal error’ error while using subversion, check the disk space on the server : $ df You’re more than likely out of space. [dave@dev2:~/]$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/vg0-rootvol 73608360 73605908 0 100% /

Browser detection with PHP

hello@daveperrett.com (Dave Perrett) — Mon, 23 Jun 2008 00:00:00 +0000

You can use PHP’s get_browser() function to find out information about user’s browsers, but it takes a little setting up.

Force MySQL Encoding to UTF8

hello@daveperrett.com (Dave Perrett) — Mon, 23 Jun 2008 00:00:00 +0000

Often MySQL will need to be forced to return results in UTF8 encoding. There are two ways to do this:

PHP5 on OS X Leopard

hello@daveperrett.com (Dave Perrett) — Mon, 23 Jun 2008 00:00:00 +0000

PHP5 is already installed on Leopard by default - all you have to do is turn it on.

First, turn on web sharing - go to System Preferences->Sharing and make sure the ‘Web Sharing’ option is turned on.

Setup 64bit CentOS (PHP5, MySQL, memcached, ketama)

hello@daveperrett.com (Dave Perrett) — Mon, 23 Jun 2008 00:00:00 +0000

I recently had to set up a few CentOS servers with PHP , MySQL , memcached and ketama, and ended up writing this script to do it. You can grab the whole thing from subversion (you’ll need the php folder as well).

Subversion Server on CentOS

hello@daveperrett.com (Dave Perrett) — Thu, 27 Mar 2008 00:00:00 +0000

Install a couple of packages via yum :

$ sudo yum install httpd subversion mod_dav_svn

Format JSON with PHP

hello@daveperrett.com (Dave Perrett) — Tue, 11 Mar 2008 00:00:00 +0000

jQuery i18n Translation Plugin

hello@daveperrett.com (Dave Perrett) — Thu, 21 Feb 2008 00:00:00 +0000

2013-03-28 Update : This plugin is now hosted on GitHub

2010-09-29 Update : This plugin has been moved from subversion to git, and now has a dedicated project page . Subversion updates will be discontinued, so please update your links to point to the latest version!

jQuery SimpleColor Color-Picker

hello@daveperrett.com (Dave Perrett) — Tue, 18 Dec 2007 00:00:00 +0000

2013-03-28 Update : This plugin is now hosted on GitHub

2010-09-29 Update : This plugin has been moved from subversion to git, and now has a dedicated project page. Subversion updates will be discontinued, so please update your links to point to the latest version!

Adding Appfuse Dependencies

hello@daveperrett.com (Dave Perrett) — Wed, 05 Dec 2007 00:00:00 +0000

I recently had trouble importing the com.sun.media.jai imaging library into appfuse :

The import com.sun.media.jai cannot be resolved

To add a dependency in your pom.xml, first add the new repository (may not be strictly necessary if the library is already in the default appfuse repositories) :

Complex Constants in Java

hello@daveperrett.com (Dave Perrett) — Wed, 05 Dec 2007 00:00:00 +0000

If you want to assign a complex class (such as a HashMap / ArrayList etc) as a constant in Java, use the static initializer block construct :

Default Values With Hibernate Annotations

hello@daveperrett.com (Dave Perrett) — Wed, 05 Dec 2007 00:00:00 +0000

To set the default value of a field with Hibernate, you can use the columnDefinition argument :

MySQL Delete On Joined Tables

hello@daveperrett.com (Dave Perrett) — Sun, 02 Dec 2007 00:00:00 +0000

If you want to (for example) delete all users with the guest role from your database : DELETE FROM user WHERE EXISTS ( SELECT * FROM role WHERE role.id = user.role_id AND role.name = 'guest' );

Get complete AppFuse sources

hello@daveperrett.com (Dave Perrett) — Wed, 28 Nov 2007 00:00:00 +0000

To get the complete, exploded source of an AppFuse application, run : $ mvn appfuse:full-source

Appfuse "failed to lazily initialize a collection of role"

hello@daveperrett.com (Dave Perrett) — Tue, 27 Nov 2007 00:00:00 +0000

If you are getting a failed to lazily initialize a collection of role error in AppFuse , you need to un-comment the lazyLoadingFilter filter and associated filter-mapping in src/main/webapp/WEB-INF/web.xml . <filter> <filter-name>lazyLoadingFilter</filter-name> <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class> </filter> <filter-mapping> <filter-name>lazyLoadingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>

Skip AppFuse Tests

hello@daveperrett.com (Dave Perrett) — Tue, 27 Nov 2007 00:00:00 +0000

To skip tests when compiling/running AppFuse applications, add the -Dmaven.test.skip=true argument to your Maven call : $ mvn jetty:run-war -Dmaven.test.skip=true

Hibernate OneToMany Relationships

hello@daveperrett.com (Dave Perrett) — Mon, 26 Nov 2007 00:00:00 +0000

Here’s an example of a one-to-many relationship using Spring MVC and Hibernate with annotations. The Album class has many Photo s, and each Photo belongs to an Album.

Hibernate 'TYPE=storage_engine is deprecated'

hello@daveperrett.com (Dave Perrett) — Wed, 21 Nov 2007 00:00:00 +0000

If you are getting errors similar to WARN [main] JDBCExceptionReporter.logWarnings(49) | 'TYPE=storage_engine is deprecated; use ENGINE=storage_engine instead' in hibernate, it probably means you are using MySQL5 but have your application set up for MySQL4. In your applications database settings config file ( pom.xml in my case, otherwise might be in properties.xml or something) change the hibernate.dialect setting from MySQLInnoDBDialect to MySQL5InnoDBDialect : <hibernate.dialect>org.hibernate.dialect.MySQL5InnoDBDialect</hibernate.dialect>

Multibyte-safe CSV Parser

hello@daveperrett.com (Dave Perrett) — Thu, 09 Aug 2007 00:00:00 +0000

I recently had to write a PHP CSV parser for a project, and found the built-in fgetcsv function fairly useless for real-world CSVs (where some fields are quoted and some aren’t for example, or where escaped delimiters or quotes are present inside the field text). This function should handle :

Lines where some fields are quoted and some aren’t
Lines where quoted fields have ’escaped’ quotes inside them
Lines where non-quoted fields have ’escaped’ delimiters inside them
Lines where the quote is ’escaped’ by another quote (the default behaviour for Excel CSV exports)
Lines containing multi-byte strings

JScript Debugger for IE

hello@daveperrett.com (Dave Perrett) — Thu, 26 Jul 2007 00:00:00 +0000

First, download and install the debugger from the IE Blog

Next, you need to make sure that debugging is enabled in the IE options. Go to Tools->Internet Options->Advanced and make sure these options are de-selected :

Javascript Hash Class