How-To Guides

Practical answers to specific development questions — each with examples you can use today.

Practical answers to specific development questions — each with examples you can use today. Pick a topic and find the answer you need.

AI

How do I create an agent with LangChain and LangGraph? — Build agentic workflows using LangChain’s graph-based orchestration.
How do I generate posts and apps with AI? — Use generative AI to scaffold content and applications.
What is machine learning? — Core concepts, training loops, and when ML is the right tool.

Architecture

How do I use Seamonkeys as an architecture case study? — Evaluate architectural concepts and framework decisions with a non-proprietary example.

AWS

How do I push Docker images to ECR with GitHub Actions? — Automate container builds and deployments to Amazon ECR.

Dart

How do I create and run a Dart project? — Project setup, pub, and running your first Dart application.
How do I make network requests in Dart? — HTTP calls, JSON parsing, and error handling patterns.
How do I work with files in Dart? — Reading, writing, and managing file system operations.
How do I write and run tests in Dart? — Unit tests, test runners, and assertion patterns.

Databases

How do I set up Postgres? — Install, configure, and connect to a local Postgres server.
How do I set up Redis? — Install and configure Redis for development caching.
How do I set up Memcached? — Install and configure Memcached for key-value caching.
How do I debug Postgres sequences? — Diagnose and fix sequence drift and identity column issues.
How do I restore a local MySQL database? — Recover a corrupt MySQL database from improper shutdowns.

Elixir

How do I query the database from the IEx console? — Use Ecto and IEx to inspect and query your data at runtime.
How do I join and group query results in Phoenix? — Compose Ecto queries with joins, group_by, and the pipe operator.

Flutter

How do I create and run a Flutter project? — Set up a new Flutter app and run it on emulators and devices.
How do I navigate between screens in Flutter? — Use Navigator, named routes, and deep linking.
How do I manage state in Flutter? — setState, Provider, Riverpod, and BLoC patterns compared.
How do I make network requests in Flutter? — HTTP, Dio, and error handling for API calls.
How do I persist data locally in Flutter? — SharedPreferences, Hive, and SQLite for local storage.
How do I write and run tests in Flutter? — Unit, widget, and integration testing patterns.

Git

How do I export files from a GitHub repository? — Download specific files and directories without cloning the whole repo.
How do I ignore files in Git? — Configure .gitignore patterns for common frameworks and editors.
How do I remove files from Git history? — Permanently purge sensitive files from your repository history.

Java

How do I disable Redis in Spring Boot? — Exclude Redis auto-configuration when you don’t need it.
How do I generate a test phone number? — Create realistic phone numbers for test fixtures.
How do I use JPA sequence generators with Hibernate? — Configure identity and sequence-based ID generation.
How do I use native SQL queries in JPA? — Write native queries for complex database operations.
How do I read a file into a String in Java? — Load classpath and filesystem resources into Strings.
How do I round numbers in Java? — BigDecimal, Math.round, and precision control.
How do I use simple string templates in Java? — String formatting and template options beyond concatenation.
How do I autowire beans in Spring? — Constructor injection, qualifier resolution, and common pitfalls.
How do I use certificates with a Java keystore? — Import, manage, and reference SSL certificates in JVM keystores.

Jetpack Compose

How do I set up a Compose project? — Add Compose dependencies, configure the build, and write your first composable.
How do I create a Hello World app with Compose? — Build a minimal app from scratch — understand every file and every composable.
How do I manage state in Compose? — Using remember, mutableStateOf, StateFlow, ViewModel, and state hoisting.
How do I navigate in Compose? — Type-safe routing, nested graphs, deep links, and bottom navigation.
How do I use Material Design 3 in Compose? — Theming, color schemes, typography, and Material 3 components.
How do I write tests in Compose? — Testing composables with semantics, assertions, and UI automation.

Kotlin

How do I get started with Kotlin and Spring? — Boot config, routing, and building a REST API with Kotlin.
How do I configure the Jackson ObjectMapper in Kotlin? — Null handling, data classes, and JSON serialization tips.
How do I create lists in Kotlin? — ListOf, mutableListOf, and collection initialization patterns.
How do I use nested annotations in Kotlin? — Compose and layer annotations for validation and configuration.
How do I override the TypeIdResolver in Kotlin? — Custom polymorphic deserialization with Jackson.
How do I use MockK for testing? — Mocking, verifying, and stubbing Kotlin classes and coroutines.

Mac

How do I fix Illustrator with Java 7 on Mac? — Resolve Java runtime conflicts that break Adobe Illustrator.
How do I set JAVA_HOME on Mac? — Configure JAVA_HOME for multiple JDK versions on macOS.

Mobile

How do I publish to the Apple App Store? — Certificates, provisioning, App Store Connect, and submission steps.
How do I publish to the Google Play Store? — Signing, upload, and release management for Android apps.

Postgres

How do I use array columns in Postgres? — Define, insert, and query array-type columns.

Ruby

How do I add character encoding to the Heroku buildpack? — Get charlock_holmes working on Heroku with a custom buildpack.
How do I add image processing to the Heroku buildpack? — Compile image libraries for Rails image manipulation on Heroku.
How do I bulk insert records that don’t already exist? — Upsert patterns with ActiveRecord and raw SQL.
How do I cancel a Recurly subscription programmatically? — Use the Recurly Ruby SDK to cancel and manage subscriptions.
How do I create a custom tag with attributes in Jekyll? — Parse and render custom Liquid tags with named parameters.
How do I eager load children in ActiveRecord? — Use includes and preload to avoid N+1 queries.
How do I fix a handlebars.vm include error? — Resolve gem version conflicts that cause runtime load errors.
How do I fix the Psych YAML issue on RVM and macOS? — Fix path2class errors when RVM and Homebrew Ruby conflict.
How do I flatten a hash into a string? — Convert nested hashes into flat key-value strings.
How do I look up HTTP status codes in Rails? — Symbol and numeric status code reference for Rails controllers.
How do I pass variables to a partial in Rails? — Use locals to send data from parent templates to partials.
How do I recover from a load error? — Auto-install missing gems when a LoadError is raised.
How do I use RSpec tips and tricks? — Run individual tests, bisect failures, and add detail to output.
How do I run SQL in Rails migrations? — Execute raw SQL alongside schema changes in migration files.
How do I set up a custom Ruby buildpack? — Add compilation steps to the standard Heroku Ruby buildpack.
How do I get the size of an ActiveRecord collection? — Count, length, and size — when to use each method.
How do I convert a string to a class reference? — Use constantize and safe_constantize for dynamic class lookup.
How do I get unique records from a list? — Deduplicate ActiveRecord result sets while preserving objects.
How do I URL-encode a string in Ruby? — Encode query parameters and form data using standard library methods.
How do I use modules for testing? — Mock behavior by including test modules instead of full mocking frameworks.

Unix

How do I decrypt GPG data? — Decrypt files and streams using GPG from the command line.
How do I flush Memcached? — Clear the Memcached cache via telnet and command-line tools.
How do I resolve APT dependencies? — Fix broken package dependencies on Debian and Ubuntu.
How do I use a serverless runtime? — Configure and deploy serverless functions for common runtimes.