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

4 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

5 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

5 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

5 years

by Chris Bloom in Code Snippets

Read an updated article on my Rails shortcuts: Bash shortcuts to run Rails commands through Spring, Bundler, or ye olde scripts

Like any developer, I spend a lot of time in the terminal typing out commands. Anything I can do to cut down on keystrokes is a daily win, which is why I’ve got over 50 bash alias entries.

I frequently have to work on a several different Rails projects at a time, ranging in versions from 2.3 – 4.0. Hammering out commands for console, server or generate can get pretty tedious by the end of the day, so I came up with a couple shortcuts that I’m particularly fond of:

# RUBY / RUBY ON RAILS COMMANDS
alias rails_mv="rails -v | sed 's/Rails \([0-9]\).*/\1/g'"
alias bexec='bundle exec'
alias brake='bundle exec rake'
function cons () {
  if [ `rails_mv` -lt 3 ]; then
    ./script/console "$@"
  else
    bexec rails c "$@"
  fi
}
function gen () {
  if [ `rails_mv` -lt 3 ]; then
    ./script/generate "$@"
  else
    bexec rails g "$@"
  fi
}
function srv () {
  if [ `rails_mv` -lt 3 ]; then
    ./script/server "$@"
  else
    bexec rails s "$@"
  fi
}
alias sandbox='cons --sandbox'

# RUBY / RUBY ON RAILS COMMANDS

alias rails_mv="rails -v | sed 's/Rails $[0-9]$.*/\1/g'"

alias bexec='bundle exec'

alias brake='bundle exec rake'

function cons () {

if [ `rails_mv` -lt 3 ]; then

./script/console "$@"

else

bexec rails c "$@"

}

function gen () {

if [ `rails_mv` -lt 3 ]; then

./script/generate "$@"

else

bexec rails g "$@"

}

function srv () {

if [ `rails_mv` -lt 3 ]; then

./script/server "$@"

else

bexec rails s "$@"

}

alias sandbox='cons --sandbox'

What I like most about the cons, srv and gen commands is that they eliminate the mental overhead of context switching when going from the old 1.x and 2.x projects where each command is a separate bin file versus the newer 3.x+ project where they are just arguments to the rails command – It’s the same alias for every project.

alias bash commands console generate rails server shortcut

Testing for a redirect using Capybara and Selenium WebDriver

7 years

by Chris Bloom in Code Snippets

I just spent the better part of 8 hours trying to figure out how to do this. The Selenium WebDriver API docs are pretty bewildering especially when it comes to trying to interact with the HTTP response or request itself because those constructs are abstracted quite a bit.

Then /^I should be on the (.*) page$/ do |page_name|
  object = instance_variable_get("@#{page_name}")
  page.current_path.should == send("#{page_name.downcase.gsub(' ','_')}_path", object)
  page.status_code.should == 200
end

Then /^I should be redirected to the (.*) page$/ do |page_name|
  page.driver.request.env['HTTP_REFERER'].should_not be_nil
  page.driver.request.env['HTTP_REFERER'].should_not == page.current_url
  step %Q(I should be on the #{page_name} page)
end

Then /^I should be on the (.*) page$/ do |page_name|

object = instance_variable_get("@#{page_name}")

page.current_path.should == send("#{page_name.downcase.gsub(' ','_')}_path", object)

page.status_code.should == 200

end

Then /^I should be redirected to the (.*) page$/ do |page_name|

page.driver.request.env['HTTP_REFERER'].should_not be_nil

page.driver.request.env['HTTP_REFERER'].should_not == page.current_url

step %Q(I should be on the #{page_name} page)

end

Which we can use in a Cucumber feature like so:

Given I am on the homepage
When I click on the link to add a widget
Then I should be able to complete the widget form
  And I should be redirected to the widget page
  And I should see a confirmation message
  And I should see the widget listed

Given I am on the homepage

When I click on the link to add a widget

Then I should be able to complete the widget form

And I should be redirected to the widget page

And I should see a confirmation message

And I should see the widget listed

cucumber rails tdd testing

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Code Snippets

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

Cache busting AJAX requests and redirects

Dynamic enum fields in nested association forms in Rails Admin

Some useful Bash shortcuts for Ruby on Rails commands

Testing for a redirect using Capybara and Selenium WebDriver

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