Code Snippets

Small snippets of code that I find interesting or useful. Generally my own work, but I will cite sources if not.

Bash shortcuts to run Rails commands through Spring, Bundler, or ye olde scripts

6 years

Just about a year ago to date I posted some useful Bash shortcuts for Ruby on Rails commands. These are mix of aliases and functions that detect what version of Rails is present and routes commands which ever way that version expects, i.e. ./script/console versus rails console. Now that Rails 4.1 ships with Spring by default, there is yet one more way commands could be routed – through the spring binstubs. I’ve recently updated my shortcuts to account for this. Now my commands will use the binstubs if they are present, or fallback to the other version-dependent methods.

# RUBY / RUBY ON RAILS COMMANDS alias bexec='bundle exec' alias rails_mv="bexec rails -v | sed 's/Rails $[0-9]$.*/\1/g'" # Alias the rake command to Spring binstubs or fallback to "bundle exec" # http://goo.gl/HkhHAf, http://goo.gl/STtIvF function brake { if [ -f bin/rake ] then bin/rake "$@" else if [ `rails_mv` -lt 3 ]; then rake "$@" else bexec rake "$@" fi fi } function brails { if [ -f bin/rake ] then bin/rails "$@" else bexec rails "$@" fi } function cons { if [ `rails_mv` -lt 3 ]; then ./script/console "$@" else brails c "$@" fi } function dbcons { if [ `rails_mv` -lt 3 ]; then echo "Not supported in this version of Rails (`rails -v`)" else brails db "$@" fi } function gen { if [ `rails_mv` -lt 3 ]; then ./script/generate "$@" else brails g "$@" fi } function srv { if [ `rails_mv` -lt 3 ]; then ./script/server "$@" else brails s "$@" fi } function run { if [ `rails_mv` -lt 3 ]; then ./script/runner "$@" else brails r "$@" fi } alias sandbox='cons --sandbox'

H/T to makandracards for helping me figure this out.

Cache busting AJAX requests and redirects

7 years

by Chris Bloom in Code Snippets, Programming

AJAX get and head requests are cached by default. This can cause problems when AJAX requests use the same URLs as a user would use during normal site navigation. jQuery can disable caching on a global or per-request basis. When doing so, jQuery adds a _={timestamp} parameter to the query string which should make each request unique. However, there are cases where an AJAX request results in a redirect which jQuery will happily follow. When that happens the _={timestamp} isn’t automatically appended to the new request, so the final response can still end up being cached by the browser even when you’ve told jQuery not to cache it. You can get around this in 2 ways:

Make sure all redirects persist the _={timestamp} parameter, if present
Add the proper header response parameters to prevent the browser from caching the request.

Here’s an easy way to implement the 2^nd solution in Rails:

# app/controllers/application_controller.rb class ApplicationController < ActionController::Base before_filter :set_cache_buster_for_xhr private # Prevent AJAX requests/redirects from being cached def set_cache_buster_for_xhr if request.xhr? response.headers["Cache-Control"] = "no-cache, no-store, max-age=0, must-revalidate" response.headers["Pragma"] = "no-cache" response.headers["Expires"] = "Fri, 01 Jan 1990 00:00:00 GMT" end end end

ajax browser cache control expires header jquery pragma rails response revalidate store

Dynamic enum fields in nested association forms in Rails Admin

7 years

by Chris Bloom in Code Snippets, Programming

We’ve had a few projects at Panoptic Development recently that made use of the RailsAdmin gem. Out of the box, RA satisfied about 95% of what we needed to do to complete each project, but there were a few edge requirements that we either had to make do without or find workarounds for. Don’t get me wrong, RA is a wonderful utility for quickly spinning up an administrative area for your Rails app. It’s loaded with really slick bells-and-whistles, and it has an incredibly flexible DSL for configuration. However, there are a few things it just doesn’t seem to be able to handle as-is and for which I’ve searched high and low for solutions for the last 9 months. I’m happy to report that I finally cracked one of these problems, and it wasn’t even all that complicated in the end.

(more…)

ajax association coffeescript dynamic enum enumeration form has_many javascript jquery linked nested rails rails_admin ruby select

Some useful Bash shortcuts for Ruby on Rails commands

7 years

by Chris Bloom in Code Snippets

Code Snippets

Bash shortcuts to run Rails commands through Spring, Bundler, or ye olde scripts

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Cache busting AJAX requests and redirects

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Dynamic enum fields in nested association forms in Rails Admin

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Some useful Bash shortcuts for Ruby on Rails commands