...which records a user sees, which transitions they may trigger — to the state. You test state-dependent behavior at the right level: end-to-end for the business process, unit...
...as it's getting reviewed. This could be a typical state flow for a movie: stateDiagram-v2 [*] --> draft draft --> pending pending --> declined: Reason declined --> pending pending --> published Changes to the...
...rails_performance (https://github.com/igorkasyanchuk/rails_performance) provides a lot of valuable information with very little setup cost. It only needs Redis which we use in the majority of our applications anyway...
Only problematic requests (> 500 ms) Longer history than "Recent requests" The "500 Errors" screen self-explanatory and hopefully always empty The "Custom Events" screen Let's you easily add...
My RubyMine (and it seems like many other Java GUI applications) crashes the Compiz window decorator almost every time on exit. This also seems to happen for the Unity decorator...
...Update: The commited fix from below seems to have made it into the stable Ubuntu repository. Easy mode You can restore window decorations by executing this command: gtk-window-decorator...
When you need test images, instead of using services like lorempixel or placehold.it you may generate test images yourself. Here we build a simple SVG image and wrap it into...
...a data: URI. All browsers support SVG, and you can easily adjust it yourself. Simply set it as an image's src attribute. JavaScript Simple solution in modern JavaScript, e.g...
...operators typeof and instanceof which work very differently. JavaScript has some primitive types, like string literals, that are not objects (as opposed to Ruby, where every value is an object...
...Some values are sometimes a primitive value (e.g. "foo") and sometimes an object (new String("foo")) and each form requires different checks There are three different types for null (null...
Defining one callback several times in the same class behaves different in ActiveRecord and ResourceController. While in ActiveRecord the callbacks are enqueued, they overwrite each other in ResourceController. ActiveRecord - a...
...common practice class Post < ActiveRecord::Base does 'post/behavior' before_validation :do_something end module Post::BehaviorTrait as_trait do before_validation :do_something_else end end do_something_else and...
...is hard coded. A popular example is extension_allowlist, which returns an array of strings and let's you only upload files that have a filename with an extension that...
...matches an entry in that array. Another useful validation can be size_range, which gives you a little bit of control over how your storage gets polluted.
Here is a bash script that I use to auto-configure displays on Ubuntu 24.04 with Xorg. Background Ubuntu always sets the primary display to the 1st (i.e. internal) display...
...bottom-aligned (the default would be aligned at their top edges). As an oddly specific bonus (you may not need this), I adjust my internal display's resolution when connected...
...are attacked constantly. This lesson covers the most common attacks like XSS, CSRF and SQL injection, how Rails protects you, and where you still need to be careful. Important
Learning goals You can explain the CIA triad — confidentiality, integrity, availability — and sort any threat into it. You can explain how the most common attacks on web applications...
Code that works is not enough; it must stay easy to change. This lesson introduces the principles of maintainable code: avoiding duplication, small responsibilities, clear names and loose coupling.
...in teacher mode. Learning goals You can explain why working code isn't enough: software entropy, and the cost of change over an application's lifetime. You can recognize duplication...
Rails supports time zones, but there are several pitfalls. Most importantly because Time.now and Time.current are completely different things and code from gems might use one or the other.
Your life will be easier if your application does not need to support time zones. Disable them like this: config.time_zone = 'Berlin' # Your local time zone config.active_record.default_timezone...
Webmocks hash_including is similar to RSpec::Mocks::ArgumentMatchers#hash_including. Be aware that hash_including (webmock v3.0.1) doesn't parse integer values to String. Without hash including you would...
uri = URI('http://example.com/?foo=1&bar=2') stub_request(:get, 'example.com').with(query: {foo: 1, bar: 2}) Net::HTTP.get(uri) # ===> Success If you only want to check if foo is present...
The git doc states on the difference of these two commands: git-restore[1] is about restoring files in the working tree from either the index or another commit. This...
...The command can also be used to restore the content in the index with --staged, or restore both the working tree and the index with --staged --worktree. By default, if...
SQL is the language used to talk to a database. This lesson covers reading and changing data, joins, indexes and transactions — and the craft of turning prose requirements into a...
...database schema. Important Work on this lesson in teacher mode. Learning goals You can explain what a relational database is and how an application talks to it (server, client, credentials...
Sometimes a form edits a record together with its child records, like a movie with its showtimes. This lesson covers Rails' nested attributes and how to build and test such...
...in advisor mode. Learning goals You can explain how nested attributes let one form save a record together with its child records in a single transaction — all of it or...
...you know how to make it prove its answers. This lesson teaches both, and shows where the canonical documentation lives when you want to learn instead of look up.
You can make the agent back up an uncertain answer, e.g. by citing sources, searching the web or running an experiment in the app — and you prefer the experiment...
...Work on this lesson in builder mode. Learning goals You can explain why JavaScript is single-threaded and non-blocking, and what the event loop does with tasks and microtasks...
...You can explain the difference between synchronous and asynchronous APIs, and why a network request cannot simply return its response. You can work with callbacks, Promises and async/await, and translate...
...previously announced it would not charge royalties for such video through December 31, 2015 (see http://www.mpegla.com/Lists/MPEG%20LA%20News%20List/Attachments/226/n-10-02-02.pdf), and today’s announcement makes clear that royalties will continue not to...
...be charged for such video beyond that time. Products and services other than Internet Broadcast AVC Video continue to be royalty-bearing...
Shoulda Matchers don't provide canditional validations (validations with if: option). Here is how to write tests for the condition: Class: class Employee < ActiveRecored::Base validates :office, presence: true, if...
describe Employee do describe '#office' do context 'is a manager' do before { allow(subject).to receive(:manager?).and_return(true) } it { is_expected.to validate_presence_of(:office) } end context 'is...
Browsers differ in which HTML, CSS and JavaScript features they support. This lesson covers how to find out what you can use, which browsers we support, and how transpilation, polyfills...
...lesson in advisor mode. Learning goals You can explain why browsers differ in feature support and look up whether a feature is safe to use, e.g. on Can I Use...
Embedding videos on a website is very easy, add a tag to your source code and it just works. Most of the time. The thing is: Both the operating...
...an 0.x version and has quite some development dependencies. It has the Apache license. streamio-ffmpeg seems to be perfect, but had its last release in 2016. It offers...
...the same child table, declare a has_many association per condition with its own scope and dependent: :restrict_with_error, then declare the plain dependent: :destroy association last.
...The example below uses two scoped associations to keep things readable, but the same approach works with one, three, or any number of independent restrictions. class Account < ApplicationRecord
RAG is often equated with vector databases, embeddings, and semantic search. But RAG ("Retrieval-Augmented Generation") really is just 'put relevant data in the prompt' — the retrieval mechanism is up...
...to you. If your app already has any working search functionality, you can build a useful RAG pipeline with it. Semantic search can still be included later on, if really...
If you're on Ubuntu: sudo apt-get install ruby-dev On other platforms: Look for a package containing ruby header files. On Red Hat that's "ruby-devel" likely...