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Repeats

Databases don't order rows unless you tell them so

There is no such thing as a "default order" of rows in database tables.

For instance, when you paginate a result set: When using LIMIT, it is important to use an ORDER BY clause that constrains the result rows into a unique order. Otherwise you will get an unpredictable subset of the query's rows. You might be asking for the tenth through twentieth rows, but tenth through twentieth in what ordering? The ordering is unknown, unless you specified ORDER BY.

Capybara: Disable sound during Selenium tests

If the application under test makes sound, you probably want to disable this during integration testing.

You can use the args option to pass parameters to the browser. For Chrome:

Capybara.register_driver :selenium do |app|
  Capybara::Selenium::Driver.new(app, browser: :chrome, args: ["--mute-audio"])
end

I haven't found a corresponding command line option for Firefox.

Hat tip to kratob.

Partially disable animations for Angular 1.4+

If you use Angular 1.4+ together with Angular Animate, all ng-show, ng-hide, ng-class etc. are animated on default.

If you want only some elements to be animated there are 2 possibilities: Either disable animations globally and only run animations if the element has a certain class or enable animations globally and add a certain class if no animation is wanted.

Option 1: Enable animations only for html elements with class 'animate'

```
@app.config ['$animateProvider', ($animateProvider) ->
$animateProvider.classNameFilter(/\ban…

Ruby 1.8.7: Bundler crashes with "deadlock" and core dump

Error

deadlock 0x7f8a4160a360: sleep:- (main) - /home/me/.rbenv/versions/1.8.7-p375/lib/ruby/gems/1.8/gems/bundler-1.14.3/lib/bundler/worker.rb:43
deadlock 0x7f8a38c03b08: sleep:-  - /home/me/.rbenv/versions/1.8.7-p375/lib/ruby/gems/1.8/gems/bundler-1.14.3/lib/bundler/worker.rb:56
*** longjmp causes uninitialized stack frame ***: /home/me/.rbenv/versions/1.8.7-p375/bin/ruby terminated

… followed by a backtrace, memory map and more.

Fix

The culprit seems to be Bundler 1.14 when used with Ruby 1.8.7. [Downgrade to the maximu…

RSpec matcher to check if two numbers are the same

You can usually just use the eq matched to compare two numbers:

expect(deal.total).to eq(120)

If the actual value is a BigDecimal, you might have issues when you match it against a Float:

expect(deal.total_price).to eq(1200.99)

In these cases, try matching it against another BigDecimal:

expect(deal.total_price).to eq BigDecimal(1200.99)

If you don't like the syntax, our rspec_candy gem has a matcher that will compare Fixnums (integers), Floats and `BigDecima…

External contentAuto-destruct in 38 days

Unpoly 0.33 and 0.34 released

0.33.0

Compatible changes

  • When a fragment updates cannot find the requested element, you can now define a fallback selector to use instead.

    A { fallback } option has been added to all Javascript functions that update fragments, like up.replace().

    Also an [up-fallback] attribute has been added to all CSS selectors that update fragments, like for a[up-target].

    You can also define fallbacks globally using the [up.dom.config](http://unpoly.com/up.dom.con…

Repeats

Waiting for page loads and AJAX requests to finish with Capybara

If you're using the Capybara webdriver, steps sometimes fail because the browser hasn't finished loading the next page yet, or it still has a pending AJAX request. You'll often see workarounds like

When I wait for the page to load
Then ...

Workarounds like this do not work reliably, will result in flickering tests and should be avoided. There is no known reliable way to detect if the browser has finished loading the page.

Solution

Instead you should wait until you can observe the result of a page load. E.g. if yo…

Repeats

How to search through logs on staging or production environments

We generally use multiple application servers (at least two) and you have to search on all of them if you don't know which one handled the request you are looking for. Capistrano can help you with that by running commands on multiple servers.
Logs usually live in /var/www/<project-environment-name>/shared/log.
You can use grep in this directory to only search the latest logs or zgrep to also search older (already zipped) logs. `zg…

Never use SET GLOBAL sql_slave_skip_counter with a value higher than 1

If you have a replication error with MySQL and you know the "error" is okay (e.g. you've executed the same statement at the same time on 2 masters which sync each other), you can skip this error and continue with the replication without having to set up the slave from the ground up.

stop slave;
set global sql_slave_skip_counter = 1;
start slave;

But what if you have multiple errors which you want to skip? (e.g. you've executed multiple statement at the same time on 2 masters which sync each other)
Still do not use a value highe…

Error "undefined method last_comment"

This error message may occur when rspec gets loaded by rake, e.g. when you migrate the test database.

NoMethodError: undefined method 'last_comment' for #<Rake::Application:0x0055a617d37ad0>

Rake 11 removes a method that rspec-core < 3.4.4 depends on. To fix, lock Rake to < 11 in your Gemfile:

  gem 'rake', '< 11', # Removes a method that rspec-core < 3.4 depends on
Repeats

Ruby: Natural sort strings with Umlauts and other funny characters

Why string sorting sucks in vanilla Ruby

Ruby's sort method doesn't work as expected with German umlauts:

["Schwertner", "Schöler"].sort
=> ["Schwertner", "Schöler"] # you probably expected ["Schöler", "Schwertner"]

Also numbers in strings will be sorted character by character which you probably don't want:

["1", "2", "11"].sort
# => ["1", "11", "2"] # you probably expected ["1", "2", "11"]

Also the sorting is case sensitive:

["a", "B"].sort
# => ["B", "a"] # yo...
Auto-destruct in 36 days

Updated: Git stash: Working with old Entries

Partial stash pop

Sometimes you only want to pop parts of the stash. Do this the way vice versa:

git stash pop
git stash -p # Now move all the unnecessary parts back into the stash

Versatile Cucumber step regarding hovering above elements

Here's a pretty useful steps that hasn't made it into Spreewald yet.

It is best used with the auto-mapper for BEM classes in features/support/selectors.rb

When I hover above [selector] element

When /^I hover above (.*) element$/ do |selector|
  page.find(selector_for(selector)).hover
end

Example:

When I hover above the album's image element

→ triggers a hover event on .album--image

rbenv: A basic introduction

Why

We have projects that have been developed using many different versions of Ruby. Since we do not want to constantly update every old project, we need to have many Ruby versions installed on our development machines.

Rbenv does that for us.

How it works

Rbenv installs ruby version and ruby gems to ~/.rbenv/versions/VERSION_NUMBER/.... This way many different Rubies can be installed at once.

When you run ruby or gem or bundler or any other Ruby binary

  • rbenv looks for a file…
Repeats

Changing versions of Rubygems and Bundler on the server

When you are changing the version of Rubygems or Bundler on a system where you've bundled into a specific directory (which is mostly the case on an application server), remember to wipe that bundle directory in addition to the user and system gems. This is required because deploying again will not overwrite the shared cached gems.

Reason is, the binaries included in your gems are turned into binstubs by Rubygems and thus implicitly rely on a certain Rubygems version. Especially when downgrading Rubygems, this may lead to issues.

A…

Repeats

Rails index route for resources named after uncountable substantives

Using uncountable resources is not recommended as it breaks Rails' magic, e.g. when using form_for. You'll always be better off using simple pluralizable resources.


Rails automatically creates path names for routes defined via the resource method. When you put resource 'user' into config/routes.rb, you can call users_path and get the path to the index action in the UsersController: /users.

However, if you have an uncountable resource like Sheep, you cannot access the index action via sheep_path, because it will…

External contentAuto-destruct in 41 days

New site for Unpoly: The unobtrusive JavaScript framework for server-side applications

Unpoly has a new website!

Aside from a shiny new frontpage, we now have a tutorial for new users. API docs have been restructured and are easier to navigate.

unpoly.com.png

How to install guard-livereload 2.5.2 on Ruby < 2.2.5

There are some inconvenient Gem dependencies. Resolve them by adding/modifying these lines in your Gemfile:

  gem 'guard-livereload', '>= 2.5.2', require: false # Fixes a security issue
  gem 'listen', '< 3.1' # 3.1 requires Ruby 2.2.5

It is not possible to install guard-livereload 2.5.2 on Ruby 1.8.7 because it depends on guard 2.8, which requires Ruby 1.9.

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