The blog has moved to http://jessehouse.com/ ... Many google searches point here so I am leaving it operational, but there will be no new posts.

Friday, December 2, 2011

Get table and column information in postgres

Use the information_schema catalog - http://www.postgresql.org/docs/9.1/static/information-schema.html

Get table and columns from the public schema




This can be useful, maybe you want to auto generate some text that creates foreign keys based on a naming convention - for instance let's say we have a ruby/rails method called make_fk_unless_exists




The 'code' column would render something like

make_fk_unless_exists :projects, :milestone_id, :milestones
make_fk_unless_exists :tasks, :project_id, :projects
...


Saturday, November 12, 2011

Sample Routes and Links with Rails 3 in the console

The content for this post is all from a gist, hopefully someone finds it useful




Resources


Wednesday, November 9, 2011

Postgres: get the number of days in an interval

-- seconds / 60 = minutes / 60 = hours / 24 = days
select (((EXTRACT(EPOCH FROM INTERVAL '2 years') / 60) / 60) / 24)::integer as number_of_days 

good resource - http://stackoverflow.com/questions/952493/how-do-i-convert-an-interval-into-a-number-of-hours-with-postgres

Saturday, October 15, 2011

Generating barcodes with ruby and rails

Recently I had to convert some functionality from an old MS Access system to a Ruby on Rails application. The Access system generated a report that included a barcode; they were using a barcode font installed on the machine running access. I figured generating the barcode server side in the web app was going to be much nicer than installing barcode fonts on the client browsers. And since this is Ruby, I figured...
There must be a gem for that 
Sure enough, the barby gem. It allows you to output your barcode as png, gif, svg, pdf, etc...

In my case I generated png barcodes and included image references to those in my view files.

Sample code




There is no pixel setting, it uses some other type of unit to determine size; using the xdim, margin and height options you can tweak the size, but I found that it was not very precise - for my use case it was good enough.

The generated barcode does not include the value, it is just the image which can be scanned using a barcode scanner, but it would be nice if there was an option to include the value below that. This is somewhat trivial to add in your view using html.

Overall I was really pleased with this gem!

Resources

Sunday, September 18, 2011

Monday, August 22, 2011

CoffeeScript with Rails 2.3 and Rails 3.0

I just uploaded a sample application that uses guard, coffee-script and a rake task to enable use of coffee-script with a rails 2.3 or 3.0 application. Check out the README file on github for details.

https://github.com/house9/with_coffee