Engineering With ROR: Digest #8
Curated and handpicked Ruby on Rails blogs.
Introduction
This edition highlights the most insightful reads and tools helping developers build smarter, faster, and more maintainable Rails applications.
From lightning-fast AI integrations using OpenAI and Claude to an under-the-hood look at how redirects and rendering work in Rails, this roundup is packed with practical guidance.
We revisit the timeless "Fat Model, Skinny Controller" philosophy and see how companies like Persona are pushing the limits of Rails in high-stakes, identity-focused domains.
Plus, we explore foundational concepts like queueing theory that can sharpen your approach to background job design.
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Top Picks ⭐
Instant OpenAI and Claude Integrations in Your Rails Apps
This video demonstrates how to quickly integrate OpenAI and Anthropic (Claude) APIs into Ruby on Rails apps using Instrumental Components, a custom component library.
These integrations allow developers to easily add AI-powered features such as content generation and prompt handling. The process involves running Rails generators that automatically scaffold necessary files like initializers, service classes, controllers, views, and routes.
Credentials are added to Rails’ encrypted configuration, and the integrations can be used via example UIs or within app logic—like rewriting blog post titles using AI. Both integrations follow a similar setup pattern and leverage their respective Ruby gems (
ruby-openaiandanthropic).The video highlights how these tools simplify and speed up AI integration in modern Rails development, and also teases additional Instrumental Components like a Stripe-powered commerce module for monetizing AI-driven features.
Redirects in Rails: Manual, Helper, and Internals
This article delves into how redirects function within Rails applications, offering insights into their implementation and underlying mechanics. It begins by explaining that an HTTP redirect is a server response instructing the browser to initiate a new request to a different URL, utilizing 3xx status codes like 301 for permanent and 302 for temporary redirects.
It emphasizes the importance of selecting the appropriate status code, particularly for SEO purposes, as search engines interpret these codes differently.
It further explores Rails'
redirect_tohelper, detailing how it simplifies the redirection process by accepting various arguments such as strings, symbols, and named routes.Additionally, it examines the internal workings of
redirect_to, highlighting its reliance onActionController::Redirectingand theheadmethod to set the response status and location.
🧼 Skinny Controllers, Fat Models – A Classic Ruby on Rails Guideline
A Classic Ruby on Rails Guideline" from Ruby Stack News emphasizes the importance of adhering to the "Fat Model, Skinny Controller" principle in Rails development.
This approach advocates for placing business logic within models to keep controllers lean and focused on handling HTTP requests and responses.
By doing so, developers can achieve better code maintainability, testability, and reusability.
The article also acknowledges that as applications grow, models can become bloated, and suggests using service objects, form objects, and other design patterns to maintain a clean and modular codebase.
Latest 🔥
Understanding the Render Method in Rails
This article delves into the versatility of Rails'
rendermethod, a fundamental tool for generating HTTP responses in controller actions.While Rails conventionally renders a view template matching the controller action name, the
rendermethod offers extensive customization.Developers can render specific templates, partials, inline content, or raw files, and specify formats like JSON or XML. For instance,
render json: @postautomatically converts the@postobject to JSON, whilerender html: "<h1>Welcome</h1>".html_safesends raw HTML. The method also supports rendering templates from other controllers using thetemplate:option.However, it's crucial to note that invoking
rendermultiple times within a single action without proper control can lead to aDoubleRenderError.To prevent this, developers should ensure that after a
rendercall, the action either returns immediately or completes execution without further rendering attempts. Understanding these nuances enables developers to craft more efficient and maintainable Rails applications.
Company Spotlight: How Persona Scales High-Stakes Identity Systems With Rails
Persona, a company specializing in identity verification, has effectively leveraged Ruby on Rails to build and scale its platform, which processes passports, government IDs, and digital credentials across over 200 countries.
According to CTO Charles Yeh, Rails' emphasis on convention over configuration has been instrumental in defining and evolving complex real-world concepts into software, particularly in the realm of domain modeling.
This approach has enabled Persona to swiftly adapt to the dynamic regulatory and fraud landscapes of industries like fintech and healthcare. Even as the company integrates AI-driven decisioning and risk signals—areas traditionally dominated by Python—Persona maintains a Rails-first philosophy, bridging the gap between Ruby and Python ecosystems.
The company's engineering culture emphasizes collaboration, ownership, and craftsmanship, with plans to expand their Ruby engineering team to support growth.
Persona's continued investment in Rails underscores its belief that the framework remains a robust foundation for building scalable, production-grade systems in high-stakes industries.
Understanding Queueing Theory
This article on queueing theory explains how fundamental concepts from this mathematical field can help developers design and scale background job systems more effectively.
It introduces key terms such as unit of work (a job), server (a processing thread or process), service time (time to complete a job), wait time (time spent in queue), and total time (the sum of service and wait).
A central principle discussed is Little’s Law, which states that the average number of jobs in a system (L) equals the arrival rate (λ) multiplied by the average time in the system (W). This helps estimate queue length and processing delays.
It also discusses utilization—the ratio of incoming jobs to processing capacity—and highlights how latency increases sharply once utilization exceeds around 70%, even before full capacity is reached. This is known as the "knee curve" and shows why it's important not to max out system resources.
Do you really know how to ORDER BY?
The Thoughtbot post “Do you really know how to ORDER BY?” emphasizes the importance of deterministic sorting in SQL to avoid flakiness and subtle bugs.
The key takeaway is that relying on a single non-unique column, such as
created_at, can result in inconsistent sort orders when values tie, which can lead to unexpected test failures, pagination drift, or incorrect production behaviorIt walks hrough a concrete example with Rails, showing how using
ORDER BY created_at DESCwithout a tie-breaker caused intermittent test failures when multiple records shared the same timestamp .The fix is straightforward: include a unique secondary field (e.g.,
id DESC) so that the sort order becomes fully deterministic. Thoughtbot also warns that this issue can affect business logic (e.g., “latest” records) and UI behaviors like pagination, since unstable ordering can cause records to reappear or disappear between pages.It concludes by urging developers always to ask, “Is my sort order deterministic?” and to add explicit tie-breakers whenever necessary—before ambiguous ordering introduces costly bugs downstream.
Weird Ruby: Anonymous Heredocs
This post explores an unconventional way to simplify Ruby’s heredoc syntax. Normally, developers use named delimiters like
<<~MARKDOWN ... MARKDOWN, but a rejected proposal suggested an anonymous delimiter style—e.g.<<~ ... ~>>.While not adopted, the post notes a clever workaround: using
_as the surrogate delimiter, as in<<~_ ... _, which effectively mimics anonymous heredocs without requiring named tokens. Although this looks a bit odd, it works in practice and maintains indentation stripping.Ultimately, it's a small hack that highlights Ruby’s flexible—but quirky—string literal capabilities, fitting with the language’s ethos of being “weird” by design. Keep Ruby weird!
How to Generate a Random String in Ruby: A Comprehensive Guide
This article provides a comprehensive guide on generating random strings in Ruby, covering both simple and secure methods. For basic use cases, developers can use arrays of characters combined with
Array#sampleto create customizable random strings.However, for security-sensitive applications like API keys, passwords, or session tokens, the recommended approach is to use Ruby's built-in
SecureRandommodule, which offers methods likeSecureRandom.alphanumericfor generating cryptographically secure strings.It also explains how to customize character sets to exclude ambiguous characters (e.g., '0', 'O', 'I', 'l') to improve readability.
Overall, it highlights the importance of choosing the right method depending on whether performance or security is the priority.
Mastering Routes in Ruby on Rails: A Developer’s Guide
This article explores Rails routing in depth, emphasizing its significance in mapping HTTP requests to controller actions.
It covers foundational concepts such as defining basic routes, utilizing RESTful conventions with the
resourcesmethod, and implementing named routes for cleaner URL generation.The guide delves into advanced topics like nested resources to represent hierarchical relationships, member and collection routes for custom actions, and namespaces for organizing controllers, particularly in admin panels or APIs.
Additionally, it discusses shallow routing to simplify deeply nested URLs and introduces routing concerns to promote DRY (Don't Repeat Yourself) principles by reusing common route definitions across multiple resources.
The article also touches on constraints, allowing developers to impose conditions on routes, and concludes with best practices for maintaining clean and maintainable routing structures in Rails applications
How to use Enumerable with Ruby Classes
This video demonstrates how to use Ruby’s
Enumerablemodule to make custom collection classes behave like arrays, enabling powerful methods such asmap,sort,find, andfirst.To use
Enumerable, you must define aneachmethod in your class, which yields elements from an internal array and returns an enumerator when no block is given. This setup allows seamless iteration and transformation of items, just like an array.For sorting to work, the objects within the collection must implement the
<=>(spaceship) operator, typically by delegating comparison to a key attribute likename.This pattern is particularly useful in scenarios like API clients, where wrapping API responses in objects can still allow for intuitive, array-like interactions. Overall,
Enumerableprovides a clean and extensible way to enhance Ruby classes that manage collections of objects.
How to use the new action_text-trix gem
A recent update to Rails has moved Trix, the rich text editor used by Action Text, into its own gem called
actiontext-trix, allowing it to be updated independently of Rails itself.Previously, Trix’s JS and CSS were bundled directly within Action Text, which made upgrades slow and dependent on Rails releases. With this change, developers can now easily stay up to date with Trix—especially important for security patches—by updating the gem rather than waiting for a new Rails version.
This is particularly beneficial for projects using import maps, which previously required workarounds for CSS and vendored files. To use it, you add the
actiontext-trixgem, remove any locally vendored Trix files, and adjust yourimportmap.rbconfig to avoid version conflicts.This setup supports any Rails version and hints at upcoming improvements, including a potentially new editor teased by the Rails core team, which may follow a similar decoupled structure.
Code Rails 10x Faster: AI-Powered Dev with Cursor
Cursor, an AI-enabled code editor, allows real-time interaction with various AI models for code editing and feedback. Taskmaster, on the other hand, helps structure and manage tasks by parsing Product Requirements Documents (PRDs) into actionable steps.
The setup involves installing both tools, configuring environment variables for API access, and initializing Taskmaster to generate a working task system integrated with AI agents.
The user walks through creating a grocery tracking app by prompting the AI to generate a PRD, parsing it into tasks, and using Taskmaster’s CLI and MCP server integration to manage task progress.
This structured workflow not only keeps the AI focused but also helps developers stay organized over time, especially when returning to a project after a break.