When you want to filter records in a model where a string column roughly matches a given term, you can use PostgreSQL’s trigram similarity search.

Writing a fuzzy query in Rails

User.where("similarity(name, ?) > 0.3", "John")

This finds all users where the name is similar to "John" with a similarity score above 0.3.

You can tune the threshold:

• Closer to 1.0 = stricter match
• Closer to 0.0 = looser match

Ordering by best match

User
  .where("similarity(name, ?) > 0.3", "John")
  .order(Arel.sql("similarity(n...

You can check the maximum client Redis database size in Sidekiq with this command.

Sidekiq.redis { |redis| puts redis.info.fetch('maxmemory_human') }
#=> 512.00M

If you just want the maximum database size for a known Redis database URL you can use the Redis Ruby client or the Redis CLI:

Redis database size via Ruby client

irb(main):002> Redis.new(url: 'redis://localhost:16380/1').info.fetch('maxmemory_human')
=> "512.00M"

Redis database size via CLI

$ redis-c...

Orca is a Linux screen reader. Since it is part of the GNOME project it should come preinstalled with Ubuntu installations.

Getting started

To turn on the screen reader you can either go to Settings > Accessibility and then activate Screen Reader in the "Seeing" section or you can simply type orca in your terminal. Alternatively you can use the default keyboard shortcut super + alt + s to toggle the screen reader.

Note

It may feel quite strange in the beginning to use a screen reader. It is constantly commenting on everyth...

In Rails, the implicit_order_column (added in Rails 6) is a configuration option that helps you define the default sorting behavior of ActiveRecord queries when no explicit ORDER BY clause is provided. This option allows you to specify a column that Rails will use to automatically sort records in a particular order when no specific ordering is given.

Since the id is typically the primary key and automatically indexed, Rails will default t...

Why Rails has multiple schema formats

When you run migrations, Rails will write your current database schema into db/schema.rb. This file allows to reset the database schema without running migrations, by running rails db:schema:load.

The schema.rb DSL can serialize most common schema properties like tables, columns or indexes. It cannot serialize more advanced database features, like views, procedures, triggers or custom ditionaries. In these cases you must switch to a SQL based schema format:

# in application.rb
config.a...

Here is a workaround for when you want to use text-wrap: balance but must also render nicely for browsers that don't support it (mostly Safari <17.5).

Step 1: Put some <br>s into your HTML

First, place explicit line breaks that should work for most cases.
This depends on your use case and is affected by e.g. container widths or user content.

<div class="my-element">
  <p>
    Average score
    <br>
 ...

DirectUpload allows you to upload files to your file storage without having to wait for the form to submit. It creates AJAX requests to persist the file within your form and wraps them in a little API. This card will show you how to use it in order to create in-place file uploads with progress and a remove button.

This is basic functionality, you may add additional elements, styles and logic to make this look fancy, but the core functionality is the same. I created a file upload that looks like this:

![Image](/makandra/625023/attachments/3...

ActiveStorage does not provide any built-in way of implementing authentication for the available DirectUpload endpoint in Rails. When using DirectUpload as JS wrapper in the frontend, be aware that its Rails endpoint is public by default, effectively allowing anyone to upload an unlimited amount of files to your storage.

The DirectUploadController from @rails/activestorage bypasses your form controller because it uploads the file using an AJAX request that runs directly, before any form roundtrip happens. This is a comfortable solutio...

PostgreSQL can cosplay as a full-text search engine. It doesn't have the features or fidelity of ElasticSearch or Algolia, but it's good enough if you just need to search and rank large volumes of text.

This card will teach you how to index, search and rank your Rails models in a PostgreSQL full-text index. We will do this without using any gems aside from ActiveRecord. While there are gems like pg_search or pg_fulltext, manual integration requires very...

Given there is a user with an attachable avatar:

class User < ApplicationRecord
  has_one_attached :avatar
end

If you want to add a preprocessed version follow these steps:

1. Add the named version and deploy

class User < ApplicationRecord
  has_one_attached :avatar do |attachable|
    attachable.variant :preview, resize_to_fit: [177, 177 * 9 / 16], preprocessed: true
  end
end

2. Preprocess this version for all existing records `bundle exec rails runner 'User.find_each { |user| user.avatar.variant(:preview).proc...

Given there is a user with an attachable avatar:

class User < ApplicationRecord
  has_one_attached :avatar
end

You can copy the avatar from one user to another user with the code below:

user_1 = User.first
user_2 = User.create!(
  avatar: {
    io: StringIO.new(user_1.avatar.download),
    filename: user_1.avatar.blob.filename.to_s,
    content_type: user_1.avatar.blob.content_type.to_s,
  }
)

Note: For large attachments you might need to use a different approach to avoid memory issues.

The key to unlocking the full potential of LLMs in coding lies in crafting precise prompts. The main challenge is learning how to structure prompts effectively to guide the model toward accurate results. Further evidence supporting this is the fact that Aider already writes ~70% of its own code (as of 02/2025). However, when starting out, your results may fall short of efficiently generating large portions of your code with the...

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 whenever I connect to a new Dock/Hub.
  • I want my primary display to be the large display.
  • My notebook is always placed left of external displays, so the 2nd display will be the center (or only) external display and should be primary.
• I also want all my displays to be placed horizontally, but bottom-aligned (the default would be aligned at their top edges)....

When debugging slow SQL queries, it’s helpful to understand the database engine's query plan. Whenever you execute a declarative SQL query, the database generates a "query plan" that outlines the exact steps the engine will take to execute the query. Most of the time, we don’t need to worry about this plan because SQL engines are highly optimized and can generate efficient execution strategies automatically. However, if a query is slow, inspecting the generated plan can help identify bottlenecks and optimization opportunities.

If you're usi...

Rails wraps your parameters into an interface called StrongParameters. In most cases, your form submits your data in a nested structure which goes hand in hand with the strong parameters interface.

Example:

curl -X POST -d "user[name]=bob" https://example.com/users

class UsersController
  def create
    User.create!(params.expect(user: [:name])) # Or User.create!(params.require(:user).permit(:name))
  end
end

This works well most of the time...

The new params.expect method in Rails 8 improves parameter filtering, addressing issues with malformed input and enhancing security. It provides a cleaner, more explicit way to enforce the structure and types of incoming parameters.

What changed

• Replaces require and permit: Combines both methods for concise parameter validation.
• Explicit Array Handling: Requires double array syntax to define arrays of hashes, improving clarity.
• Enhanced Validation: Ensures expected parameter structure, rejecting malformed input wi...

Also see the list of IRB commands.

Switching the context

Changes the "default receiver" of expressions. Can be used to simulate a "debugger situation" where you are "inside" an object. This is especially handy when needing to call private methods – just invoke them, no need to use send.

• Switch to an object: chws $object
• Reset to main: chws
• Show current context: cwws (usually shown in IRB prompt)

[Technical details](https://technology.doximity.com/articles/the-hidden-gems-of-r...

In development, we store files using ActiveStorage's disk service. This means that stored files are served by your Rails application, and every request to a file results in (at least!) one non-trivial log entry which can be annoying. Here is how to disable those log entries.

Example

Here is an example of what loading a single <img> in an example application writes to the Rails log.

Started GET "/rails/active_storage/blobs/redirect/..." for ::1 at ...
Processing by ActiveStorage::Blobs::RedirectController#show as SVG
  Parameter...

Some key highlights and points from the linked article TestProf II: Factory therapy for your Ruby tests.

The Problem with Factories in Ruby Tests

• Factories are used to easily generate test data.
• However, they can unintentionally slow down test suites by creating unnecessary or excessive associated data (factory cascades).

Understanding Factory-Induced Slowdowns

• Factories often create additional data (e.g., associated records) th...

A lesser known fact about PG enums is that they are ordered. This can be really handy when values have an implicit ordering.

Let's imagine a record Issue(criticality: string). criticality should have the following three possible values: critical, medium, low.

Sorting with Issue.all.order(criticality: :desc) will return the following order:

1. The 'medium' issue
2. The 'low' issue
3. The 'critical' issue

This happens because the database column backing the criticality attribute is a string and PG will use a [collation](...

We recently migrated a Rails application from yarn to npm. We decided to go this step instead of upgrading to > Yarn 2.0 to reduce the number of dependencies in our project.

Migration

• Remove the yarn.lock file
• Remove the node_modules folder
• Run npm install
• Replace all occurrences of yarn with npm in your project

Notes

• With npm vendored packages with dependencies create their own node_modules folder within the vendor path. We...

Slow test suites are a major pain point in projects, often due to RSpec and FactoryBot. Although minitest and fixtures are sometimes viewed as outdated, they can greatly improve test speed.

We adopted a project using minitest and fixtures, and while it required some initial refactoring and establishing good practices, the faster test suite was well worth it! Stick with me to explore how these tools might actually be a good practice.

So, why is this setup faster? Partially, it's because minitest is more lightweight than RSpec, which...

While the main goal always is to prevent long-running queries in the first place, automatic timeouts can serve as a safety net to terminate problematic queries automatically if a set time limit is exceeded. This prevents single queries from taking up all of your database’s resources and reduces the need for manual intervention that might destabilize or even crash the application.

As Rails does not set a timeout on database statements by default, the following query will run for an entire day:

ActiveRecord::Base.connection.execute("S...

On our Ubuntu machines we have nautilus file manager with nautilus-extension-gnome-terminal installed. This adds an entry to the context menu (right click) to start a gnome-terminal in the current directory. As I'm mostly using Terminator terminal, I wanted to have a similar context menu entry to launch Terminator directly. I came across this python script that does exactly that.

• Install python3-nautilus: sudo apt install python3-nautilus
• Create `/usr/share/nautilus-...