...your lambda function via terraform, this code is usually zipped and uploaded to Amazon S3 by terraform. The ZIP file's hash is then stored to terraform's state. However...
...you're collaborating with colleages e.g. via git, each run of terraform will possibly see a different hash of the code's ZIP archive and try to replace the lambda...
When doing some meta-programming magic and you want to do something for all attributes of a class, you may need to access connection or some of its methods (e.g...
...will encounter fun errors such as: PG::ConnectionBad (for missing databases on PostgreSQL) ActiveRecord::StatementInvalid: PG::UndefinedTable (when database exists, but has no tables) Generally speaking, evaluating model columns during...
...come across objects created by some gem or framework. You don't have the source code at hand, still need to inspect this object. Here are some tools to do...
...from Object. This makes the methods list drastically more relevant. You can also try subtracting other base classes like ActiveRecord::Base.methods etc. To further narrow it down you can also...
...an event handler, there are multiple methods to cancel event propagation, each with different semantics. event.preventDefault() Only prevents the default browser behavior for the click, i.e. going to a different...
...url or submitting a form. When invoked on a touchstart event, this also prevents mouse events like click to be triggered. event.stopPropagation() Prevents the event from bubbling up the DOM...
...in development. Note that there are services like badssl.com to test against weird SSL behavior. Self-signed certificates Talking to a host using a self-signed certificate will fail because...
...the certificate can not be verified. >> RestClient.get('https://self-signed.badssl.com/') RestClient::SSLCertificateNotVerified: SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed Self-signed certificates...
If you already selected an element and want to get its parent, you can call find(:xpath, '..') on it. To get the grand-parent element, call find(:xpath, '../..'). Example
...href]).to eq("http://twitter.com/") About XPath There is a good overview on XPath syntax on w3schools. But as XPath expressions can get quite complex and hard to understand for...
...agent manually. Example: # exec resource: exec { "update_rubygems_${user}_${version}": command => "${home}/.rbenv/shims/gem update --system ${version}", unless => "${home}/.rbenv/shims/gem -v | /bin/grep ${version}", } This does execute rbenv commands. If puppet runs...
Sometimes you have a file that is related to a project, while not actually being part of it. You'd like to keep them around, but others won't need...
...them – e.g. some notes, a log, or a database dump. Sure, you have a project directory – but all of it is tracked by Git. A project's tmp/ directory is...
...tell npm to install a package globally with npm -g install @puppeteer/browsers. However, it seems that its not possible that npx can run commands from global packages without referencing the...
...image, where a testing chrome and chromedriver is installed with a global npm package. Since there is no local project it was more useful to install the package in a...
In the past we validate and set default values for boolean attributes in Rails and not the database itself. Reasons for this: Older Rails didn't support database defaults when...
...the Rails upstream on constraints in the database, is adding default values in the schema of the database itself. We also encourage to set boolean attributes to not null. For...
Module imports are hoisted (internally moved to the beginning of the current scope). Therefore, it doesn’t matter where you mention them in a module and the following...
Footgun example When you're not aware of import hoisting you may be surprised that your code runs in a different order than you see in the source file...
...that's not a float! This occurs because JavaScript uses double precision floats to store numbers. So according to IEEE floating point definition only numbers between...
...and 2^53 - 1 (9007199254740991) can safely be represented in JavaScript. Note that ECMAScript 6 will probably also offer Number.MAX_SAFE_INTEGER (and Number.MAX_SAFE_INTEGER) that point to those...
...use puppet-lint to find dead code in your project: # You probably need to set some ENV Variables, see https://github.com/voxpupuli/puppet-ghostbuster#environment-variables export HIERA_YAML_PATH="/home/bob/code/puppet/hiera.yaml" export PUPPETDB_URL...
Ubuntu 18.04 uses systemd to manage services. There are basically two commands for listing all services and manipulating the state of a certain service: service and systemctl: service manages System...
...which system V init scripts are available and running / not running, you can use service --status-all: >service --status-all [ + ] acpid [ - ] alsa-utils [ - ] anacron [ + ] apache-htcacheclean [ - ] apache2 [ + ] apparmor [ + ] apport
PostgreSQL uses the C library's locale facilities for sorting strings: First, all the letters are compared, ignoring spaces and punctuation. It sorts upper and lower case letters together. So...
...the order will be something like a A b B c C Then, spaces and punctuation are compared to break ties. Example: Ruby PostgreSQL IMAGE3.jpg image2.jpg image.jpg image3.jpg image2.jpg
...discouraged to load your JavaScript by a tag in the : The reason is that a tag will pause the DOM parser until the script has loaded and executed. This will delay the browser's first contentful paint. A much better default is to load your scripts with a tag: A deferred script has many useful properties: It does not block the browser from rendering content. Deferred scripts...
...can query the entire DOM tree with querySelector() and friends. document.readyState is 'interactive'. Deferred scripts will run before the DOMContentLoaded event. That means if your code waits to initialize until...
...not necessary to add a version constraint next to your gems in the Gemfile. Since all versions are saved in the Gemfile.lock, everyone running bundle install will get exactly the...
...You are not checking in the Gemfile.lock into the version control (not recommended) A specific gem has a bug in a more recent version (adding a comment for the reason...
...posts; if you use pagination the queries will be more complicated, but the point still stands. Looks harmless enough? It is not. The problem ActiveRecord will rewrite this into a...
...query using LEFT JOINs which looks something like this: SELECT "blog_posts".*, "comments".*, "attachments".* FROM "blog_posts" LEFT OUTER JOIN "comments" ON "comments"."blog_post_id" = "blog_posts"."id"
...instead of using the UI or creating records in the Rails console. This approach saves time and gives you useful defaults and associations right out of the box.
By default, Devise sends all emails synchronously with deliver_now. To change that, Devise's readme suggests overwriting the send_devise_notification method like this: class User def send_devise...
...notification(notification, *args) devise_mailer.send(notification, self, *args).deliver_later end end However, there is one problem: When deliver_later enqueues the mail with ActiveJob, the job arguments are logged. In...
The change_column method for rails migrations support casting with a custom SQL statement. This allows us to change a column type and keep the former content as the new...
...number, 'int USING CAST(rating AS int)' end end Warning This migration's rollback strategy will fail, if any existing entry can't be casted. This is likely to happen...
In interactive commands, Git allows the user to provide one-letter input with a single key without hitting enter (docs). # Enabled this feature globally git config --global interactive.singlekey true
...enable this feature locally for a single repository git config interactive.singlekey true This allows you to hit "y" instead of "y + ENTER" to move to the next hunk.
There is a practical short list for valid/invalid example email addresses - Thanks to Florian L.! The definition for valid emails (RFC 5322) can be unhandy for some reasons, though.
...provides a built-in email regex URI::MailTo::EMAIL_REGEXP. That's the best solution to work with. /\A[a-zA-Z0-9.!\#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0...
When your public-facing application has a longer downtime for server maintenance or long migrations, it's nice to setup a maintenance page to inform your users. When delivering the...
...maintenance page, be very careful to send the correct HTTP status code. Sending the wrong status code might get you kicked out of Google, or undo years of SEO work...