If you need to export data from MySQL to a CSV, you can profit from really fast built-in methods.

This query writes the data to /tmp/geodb_coodinates.csv. And it's fast: Query OK, 337925 rows affected (0.86 sec)

SELECT * INTO OUTFILE '/tmp/geodb_coordinates.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' ESCAPED BY '\\' LINES TERMINATED BY '\n' FROM geodb_coordinates;

Cross-browser button styling can vary with browser and OS defaults, especially for image-based designs. A small Sass reset removes inconsistent padding and borders in button elements.

To clear the query cache in your MySQL database manually, e.g. for database profiling, execute the following command in your MySQL console:

RESET QUERY CACHE;

Amended, rebased, or reset commits are still reachable by SHA1 for a time; git reflog reveals recent branch positions before garbage collection removes them.

Run a newly added model callback for existing production records without replaying validations and unrelated callbacks; suitable for backfilling cached data after deployment.

Check whether form controls or buttons are disabled in Cucumber step definitions, using label-based assertions on Capybara or Webrat elements.

How to create an infinitely nestable hash that always defaults to a new hash if a key does not map to a value.

Ruby's net/http is setup to never verify SSL certificates by default. Most ruby libraries do the same. That means that you're not verifying the identity of the server you're communicating with and are therefore exposed to man in the middle attacks. This gem monkey-patches net/http to force certificate verification and make turning it off impossible.

How to write to the db 27,000 times in 24 seconds instead of 9 minutes.

Capybara error-page assertions rely on the response status code and require @allow-rescue; Selenium @javascript scenarios do not support page.status_code.

Ruby classes can be tested for direct superclass, any ancestor, or instance compatibility with superclass, ancestors, and is_a?.

Array equality without regard to order is awkward in Ruby tests; RSpec and Test::Unit provide matchers for matching elements, and plain Ruby needs custom comparison logic.

Convert accented and reserved characters to HTML entity references, or turn entity strings back into readable Unicode text, with the htmlentities gem.

Sometimes, you just need to shoot from the hip…or deploy your local changes without committing them. Put this snippet from Jesse Newland in ~/.caprc and now you can cap cowboy deploy.

These two models can be used to access the posts and associated comments of a WordPress database.

Rejected non-fast-forward pushes happen after rewriting shared history; git push --force overwrites the remote branch and can make collaborators lose commits.

Change a Git commit message before it is pushed or merged. git commit --amend updates the latest commit; interactive rebase can rewrite earlier ones.

Older unpushed commits can be amended by folding a later fix commit into them with interactive rebase and fixup, preserving history without a new visible correction commit.

Untrusted YAML can instantiate arbitrary Ruby objects and set their fields, creating a serious deserialization risk. JSON.parse or YAML.safe_load are safer alternatives.

Controller specs can fail without reaching controller code when authentication is missing, no request is triggered, or views stay unrendered.

Use the Launchy gem:

Launchy.open('http://www.ruby-lang.org/')

Gallery of fonts you can use without much hassle in LaTeX. The license of the fonts vary, but are all free. Note that the fonts not necessarily are free to distribute, and some fonts are available for non-commercial use only.

Temporarily switch directories in Ruby without leaving the process in a different working folder by using Dir.chdir with a block.

The first thing you need to understand is that the purpose of refinements in Ruby 2.0 is to make monkey-patching safer. Specifically, the goal is to make it possible to extend core classes, but to limit the effect of those extensions to a particular area of code. Since the purpose of this feature is make monkey-patching safer, let’s take a look at a dangerous case of monkey-patching and see how this new feature would improve the situation.