Having a unique selector for an element is useful to later select it from JavaScript or to update a fragment with an Unpoly. Haml lets you use square brackets ([]) to...

...with ActiveRecord instances, which have a persisted #id and will hence generate the same selector over multiple renderings of the same view. Example - @users.each do |user| .row[user] = user.name

...the transcluded content before adding it to the DOM. # Directive template: """ """ transclude: true link: (scope, element, attributes, _controller, transclude) -> transclude (content) -> # Do custom stuff element.find('.wrapper').append(content)

...much more you can do with the transclusion function. For an in-depth introduction, see this Guide to Angular Transclusion. Also read the Angular docs on this...

The need for clearfix hacks has been greatly reduced since we could layout with Flexbox or CSS Grid. However, when you do need a clearfix, there's no reason to...

...hack anymore. You can just give the clearing container display: flow-root. This is supported by all browsers except IE11...

RubyMine offers you to exclude directories from search, meaning faster search results and less "noise" in the list of result. Right-click a folder in your project tree and click...

...and other directories that you don't need to access during development and whose search results are irrelevant. They won't be deleted but simply ignored when searching across a...

Sometimes, the rails dev server doesn't terminate properly. This can for example happen when the dev server runs in a RubyMine terminal. When this happens, the old dev server...

...blocks port 3000, so when you try to start a new server, you get the error: Address already in use - bind(2) for "127.0.0.1" port 3000 (Errno::EADDRINUSE)

Ruby's regular expressions can be represented differently. When serializing them, you probably want to use inspect instead of to_s. For the examples below, consider the following Regexp object...

>> regexp.to_s => "(?mi-x:^f(o+)!)" inspect As the Ruby docs say: Perhaps surprisingly, #inspect actually produces the more natural version of the string than #to_s...

...IDENTIFIED BY 'some_password'; GRANT REPLICATION SLAVE ON *.* TO 'replicator'@'%'; Adjust MySQL configuration Edit /etc/mysql/my.cnf: server-id = 1 log_bin = /var/log/mysql/mysql-bin.log replicate-do-db = some_project_production replicate-do-db...

...other_project_production replicate-ignore-db = mysql server-id needs to be unique among all connected master and slave servers. When replicate-do-db is provided only the chosen databases...

# the value from the form field's ngModel (which means it's not sent to the # server, and old values would not be overwritten). # # This directive makes sure that...

...form fields with an invalid value return an # empty string instead of undefined. for elementType in ['input', 'textarea', 'select'] @app.directive elementType, -> priority: 1 restrict: 'E' require: '?ngModel' link: (scope, element...

You can use three different versions of the regular expression syntax in grep: basic: -G extended: -E(POSIX) perl: -P (PCRE) Difference between basic and extended: In basic regular expressions...

...the meta-characters '?', '+', '{', '|', '(', and ')' loose their special meaning; instead use the backslashed versions '?', '+', '{', '|', '(', and ')'. Difference between extended (POSIX) and perl (PCRE): E.g. \d is not supported in POSIX.

...filled out at the same time, there is no built-in validation. I've seen different solutions in the wild, each with different downsides: Private method referenced via validate: works...

...name, :nickname, xor_presence: true end Validator Here is the validator class; put it somewhere in your project. class XorPresenceValidator < ActiveModel::Validator def initialize(options) @attributes = Array.wrap(options[:attributes]).freeze...

...unwrap(). Here is how. Consider the following example element. $container = $(' Hello World ') Let's say we want to discard any tags, but keep their contents. Simply find them, then dive...

When using state_machine you sometimes need to know whether an object may execute a certain transition. Let's take an arbitrary object such as a blog article as an...

...example that has those states: A -> B -> C -> D Additionally, you have transitions between the states as shown above. Let's call the transition between 'A' and 'B' transition_ab...

If you want to to create maps within SASS/SCSS-files, it normally works like this: $some-map: (key1: value1, key2: value2) However, some maps can get big really fast, if they...

...since 2011 and it hasn't been resolved since then. Writing a map likes this: $some-map: ( key1: value1, key2: value2 ) confuses the SASS-parser and you will get an...

Note: Making a reverse proxy with nginx is much more straightforward. A reverse proxy is a "man in the middle" server that tunnels requests to another server. You can use...

...makes sure that it can fetch from HTTPS internally. You've basically built your custom SSL-stripping MITM attack server. If your proxy server should be accessible over HTTPS, use...

Sometimes it is useful to define a named scope by implementing a static method with the scope's name on the scoped class. For instance, when a method should decide...

...which existing scope should be the next link in the scope chain. Take this class for example: class Meal < ActiveRecord::Base named_scope :for_date, lambda { |date| :conditions => { :date => date...

A print stylesheet is easy to create. Choose a font suited for paper, hide some elements, done. Unfortunately print stylesheets often break as the application is developed further, because they...

...are quickly forgotten and nobody bothers to check if their change breaks the print stylesheet. This card describes how to write a simple Cucumber feature that tests some aspects of...

This is how you regain disk space from OpenStack instances if you are using kvm and qcow. If your instance used up all configured disk space once the disk file...

...remains big. You can end up in a situation where for example the instance use only 20GB disk space but the disk file on the server has 100GB (or even...

...of control”. A function that accepts a callback instead of a return value is saying, “Don’t call me, I’ll call you.”. Promises un-invert the inversion, cleanly separating...

...the input arguments from control flow arguments. This simplifies the use and creation of APIs, particularly variadic, REST and spread arguments. Note that promises are not a drop-in replacement...

Ruby's standard library includes a class for creating temporary directories. Similar to Tempfile it creates a unique directory name. Note: You need to use a block or take care...

...of the cleanup manually You can create a prefix and suffix e.g. Dir.mktmpdir(['foo', 'bar']) => /tmp/foo20220912-14561-3g93n1bar You can choose a different base directory than Dir.tmpdir e.g. Dir.mktmpdir('foo', Rails.root.join('tmp...

When using the asset pipeline your assets (images, javascripts, stylesheets, fonts) live in folders inside app: app/assets/fonts app/assets/images app/assets/javascripts app/assets/stylesheets With the asset pipeline, you can use the...

When you deploy, Rails runs assets:precompile which precompiles all assets into static files that live in public/assets. This way you have all the performance of static files...

Capistrano 2 brings the shell command which allows you to run commands on your deployment targets. There is also invoke to run a command directly from your terminal.

...allow running Capistrano tasks or shell commands, and scope to individual machines or machine roles. Unfortunately Capistrano 3 does not include these commands any more. cap shell Basics

ActionMailer per default uses http as protocol, which enables SSL-stripping. When a logged-in user follows an http link to your application, it sends the cookies along with it...

...to send emails from public parts of your application with HTTP links and emails from SSL-protected parts with HTTPS, build a before_filter. If you need certain links with...

Git allows you to set push options when pushing a branch to the remote. You can use this to build an alias that automatically pushes a branch and creates a...

...merge request for it. Put this in your ~/.gitconfig in the [alias] section: mr = push origin HEAD -o merge_request.create -o merge_request.draft Now you can do git mr and a draft...