Custom Angular Test Bootstrap
Compatibility: Angular 20+ with Jasmine 5.x and Karma 6.x
As default Angular CLI auto-generates test bootstrap via angular:test-bed-init via injecting it as a dynamic virtual module.
Custom Bootstrap
Override the main test option in angular.json → projects.{app}.architect.test.options.main: <test entry file> and [then initialize the ...
Checklist: Using Carrierwave in a Rails project
This checklist should help you to check edge cases that are not part of the default Carrierwave configuration.
- Check Default Configuration and Suggested Changes
- Use secret URLs.
- Check if you need expiring public URLs.
- Check if you need an optimized cache
- Use a [nested directory structure](https://makandracards.com/m...
Do not rescue inline in Ruby
When you are calling a method that may raise an exception that you don't care about, you might think of doing something like this:
@user = User.power_find(something) rescue User.new
Do not do that! You will be rescuing away StandardError and all its subclasses, like NameError -- meaning that even a typo in your code won't raise an error.
Instead, rescue the exception type that you are expecting:
@user = begin
User.power_find(something)...
Jasmine: Cleaning up the DOM after each test
Jasmine specs that work with DOM elements often leave elements in the DOM after they're done. This will leak test-local DOM state to subsequent tests.
For example, this test creates a <spoiler-text> element, runs some expectations, and then forgets to remove it from the DOM:
describe('<spoiler-text>', function() {
it ('hides the secret until clicked', function() {
let element = document.createElement('spoiler-text')
element.secret = 'The butler did it'
document.body.appendChild(element)
...
File System Access API: Recursive Directory Traversal
The File System Access API is a new capability of modern browsers that allows us to iterate over selected folders and files on a user's machine. Browser support is not great yet, but if the feature is only relevant for e.g. a single admin user it could still be worth using it prior to wider adaption instead of building yet another ZIP upload form.
Below is a simple compiler that i used to evaluate this feature.
!...
Rails: Adding a unique constraint for a has_one association might be a good default
Most of the time, it's a good default to add a unique index on the foreign key when using Rails’ has_one relationship. This ensures the database enforces the 1:1 constraint and raises an error if your application logic ever violates it.
class User < ApplicationRecord
has_one :session, dependent: :destroy
end
class Session < ApplicationRecord
belongs_to :user
end
create_table :users do |t|
t.timestamps
end
create_table :sessions do |t|
t.references :user, null: false, foreign_key: true, index: { unique: true ...
Rails: When to use :inverse_of in has_many, has_one or belongs_to associations
When you have two models in a has_many, has_one or belongs_to association, the :inverse_of option in Rails tells ActiveRecord that they're two sides of the same association.
Example with a has_many / belongs_to association:
class Forum < ActiveRecord::Base
has_many :posts, inverse_of: :forum
end
class Post < ActiveRecord::Base
belongs_to :forum, inverse_of: :posts
end
Knowing the other side of the same association Rails can optimize object loading so forum and forum.posts[0].forum will reference the same o...
How to update a single gem conservatively
The problem
Calling bundle update GEMNAME will update a lot more gems than you think. E.g. when you do this:
bundle update cucumber-rails
... you might think this will only update cucumber-rails. But it actually updates cucumber-rails and all of its dependencies. This will explode in your face when one of these dependencies release a new version with breaking API changes. Which is all the time.
In the example above updating cucumber-rails will give you Capybara 2.0 (because capybara is a dependency of `cucumber-rail...
Defining class methods with Modularity traits
There are two ways to define a class method from a Modularity trait. Note that the usual caveats regarding class method visibility apply.
Using def
You can def the method on self:
module SomeTrait
as_trait do
def self.foo
# ...
end
end
end
However, you cannot use it with traits parameters.
Using `define_singleton_met...
Sentry Local Logging in Ruby
Enable local logging for Sentry when:
- Debugging Sentry event capture locally
- Testing error handling without polluting production metrics
- Developing background jobs and want to see what Sentry captures
How to enable
To capture and log Sentry events locally during development without sending to the server, add this to config/initializers/sentry.rb inside the Sentry.init block:
if Rails.env.development?
# Use dummy transport to prevent actual transmission to Sentry
config.transport.transport_class = Sentry::DummyTran...
Using a virtual column for trigram indexes in PostgreSQL
Full-text search can reach its limits in terms of flexibility and performance. In such cases, trigram indexes (pg_trgm) offer a lightweight alternative.
You can base the index on a virtual column that combines multiple text attributes. A stored virtual column stores the result of an expression as if it were a real column. It is automatically updated when the source columns change and can be indexed like normal data. This keeps your query logic consistent and avoids repeating string concatenation in every search.
def searc...
Simple form examples with bootstrap
Good reference how to build bootstrap forms with simple_form.
Ruby: A small summary of what return, break and next means for blocks
Summary
- Use
returnto return from a method.returnaccepts a value that will be the return value of the method call. - Use
breakto quit from a block and from the method that yielded to the block.breakaccepts a value that supplies the result of the expression it is “breaking” out of. - Use
nextto skip the rest of the current iteration.nextaccepts an argument that will be the result of that block iteration.
The following method will serve as an example in the details below:
def example
puts yield
puts ...
Using ActiveRecord with threads might use more database connections than you think
Database connections are not thread-safe. That's why ActiveRecord uses a separate database connection for each thread.
For instance, the following code uses 3 database connections:
3.times do
Thread.new do
User.first # first database access makes a new connection
end
end
These three connections will remain connected to the database server after the threads terminate. This only affects threads that use ActiveRecord.
You can rely on Rails' various clean-up mechanisms to release connections, as outlined below. This may...
Unpoly: Passing Data to Compilers
Quick reference for passing data from Rails to JavaScript via Unpoly compilers.
Haml Attribute Syntax
# Ising hash rockets and string symbols (method calls)
= form.text_field :name, 'date-picker': true
# Curly braces or brackets (elements)
%div.container{ id: 'main', 'data-value': '123' }
Simple Values: data-* Attributes
Use for: Scalar values (IDs, strings, booleans)
%span.user{ 'data-age': '18', 'data-first-name': 'Bob' }
up.compiler('.user', (element, data) => {
console.log(...
Unpoly: Compiler Selector Patterns
Quick guide for frequently used compiler selector patterns of Unpoly.
1. BEM Component Pattern
When: Reusable UI components with multiple child elements
Examples: toggleable.js, collapsible.js, searchable_select.js
up.compiler('.toggleable', (toggleable) => {
const checkbox = toggleable.querySelector('.toggleable--checkbox')
const content = toggleable.querySelector('.toggleable--content')
// ...
})
%td.toggleable.-inverted.-ignore-when-not-empty
.toggleable--content
= form.text_fie...
Project management best practices: Budget control
When starting a project we always make a good estimate of all known requirements, and plan budgets and available developers accordingly.
Requirements change. Budgets usually don't.
To make sure a project stays on track, we update our estimates periodically and compare them to the remaining budget. If this doesn't match any more, we have to act.
To update an estimate, do the following:
- Start with the most recent estimate for the project.
- Which stories have been completed? Set their estimate to zero.
- Have any requirements cha...
Careful: `fresh_when last_modified: ...` without an object does not generate an E-Tag
To allow HTTP 304 responses, Rails offers the fresh_when method for controllers.
The most common way is to pass an ActiveRecord instance or scope, and fresh_when will set fitting E-Tag and Last-Modified headers for you. For scopes, an extra query is sent to the database.
fresh_when @users
If you do not want that magic to happen, e.g. because your scope is expens...
Firefox cancels any JavaScript events at a fieldset[disabled]
If you try to listen to events on elements that are nested inside a <fieldset disabled>, Firefox will stop event propagation once the event reaches the fieldset. Chrome and IE/Edge will propagate events.
Since we often bind event listeners to document this can be annoying.
You could solve it by...
- ...adding event listeners on elements themselves. Note that this is terrible when you have many elements that you'd register events for.
- ...adding event listeners on a container inside the
<fieldset>, around your eleme...
SQL: Fast threshold counts with LIMIT
Performing COUNT(*) on large tables is slow. Sometimes you don’t need the exact number once results exceed a certain threshold.
For example, you may only need to display 100+ in the UI. Using a plain COUNT(*) would scan all matching rows.
The following query would be pretty slow when counting many rows because it has to scan all rows.
SELECT COUNT(*) FROM movies;
Limiting within a subquery
Use a subquery with LIMIT to cap the scan early. ...
How to tweak RSpec's truncation behavior
When RSpec sets out to print any given object to the console, it will never print more than 200 characters from it. Only the first and last 100 chars from overly long strings are displayed, which sometimes means that the root cause for the failing test is buried in truncation.
For example, I could not easily make out the reason for this failure:
Failure/Error: expect { crawler.pull_new_commits }.not_to raise_error
expected no Exception...
Matching Unicode characters in a Ruby regexp
On Ruby 1.9+, standard ruby character classes like \w, \d will only match 7-Bit ASCII characters:
"foo" =~ /\w+/ # matches "foo"
"füü" =~ /\w+/ # matches "f", ü is not 7-Bit ASCII
There is a collection of character classes that will match unicode characters. From the documentation:
-
/[[:alnum:]]/Alphabetic and numeric character -
/[[:alpha:]]/Alphabetic character -
/[[:blank:]]/Space or tab -
/[[:cntrl:]]/Control character -
/[[:digit:]]/Digit -
/[[:graph:]]/Non-blank character (excludes spaces...
JavaScript: Stopping expensive work in inactive tabs
Is your application doing something expensive every few seconds? Maybe an animated slider that rotates images? Maybe you are updating data over the network every five minutes? It's a good idea to pause this if the your document tab is not even visible to the user. This saves your user's battery and data plan.
You can ask document.visibilityState or document.hidden whether this tab is visibl...
zizmor - Static analysis for GitHub Actions
The linked tool can be used to scan your CI/CD workflows for potential security issues and suboptimal defaults if they are based on GitHub Actions.
For example, it warns you about
- string interpolations that may expand into attacker-controllable code
- suboptimal defaults like e.g.
persist-credentials: truefor the checkout action - actions that are not pinned to a tag instead of a git SHA
Some of the warnings can be auto-fixed. The tool comes wi...