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Lessons (40)

• Variables, Locals, Outputs, and Validation

  Build a configurable local lab with typed inputs, useful outputs, and clear validation errors. Replace hard-coded values …

• DRY: Don't Repeat Yourself

  … Admin panel rejects valid emails 🐛 js // ❌ The same rule in three places // signup.js if (!/^[^@\s]+@[^@\s]+\.[^@\s …

• API Contracts, Gateways and Security

  … Define versioned request/response contracts, validation rules, pagination and stable error semantics. 2. Validate identity at the boundary …

• Extending Kubernetes: CRDs, Operators and Admission

  … Good CRD practice: - Define a strict schema with validation, defaults and CEL rules ( x-kubernetes-validations ). - Use the …

• Prompting and Structured Outputs

  Write clear instructions, provide context and examples, constrain responses, and validate model output in code. The big idea …

• Small Functions That Do One Thing

  … one function per AND"] - registerUser() "validates input and saves the user and sends a welcome email" → three functions …

• Putting AI Systems into Production

  … input validation, retrieval or context, provider calls, output checks, user experience, monitoring, and operational controls. The model is …

• Node.js and Express

  … routing, the middleware pipeline, validation, async error handling, project structure, configuration, security, rate limiting, logging and graceful shutdown …

• Testing, Preconditions, and Policy Checks

  Use validation, lifecycle conditions, Terraform tests, and policy checks to catch different classes of errors. Different checks answer …

• Go Web Services with Gin

  … net/http basics, Gin routes and groups, binding and validating JSON, middleware, a layered project structure, handler tests …

• Machine Learning Fundamentals

  … Estimating a home's sale price is regression. Train, validate, test The training set fits model parameters. The …

• TypeScript in Practice

  … Data from the outside world (HTTP bodies, JSON files, env vars) must be validated , and then TypeScript can …

• Advanced TypeScript for Frontend

  Model real UI states safely with generics, discriminated unions, conditional types and runtime schema validation at API boundaries …

• AI Agents and Tool Use

  … The model proposes an action; application code should decide whether the action is valid and authorized. mermaid sequenceDiagram …

• NestJS Core Concepts

  … number; } // main.ts — validate every body, strip unknown fields, convert types app.useGlobalPipes(new ValidationPipe({ whitelist: true, forbidNonWhitelisted …

• Capacity Planning, SLOs and Error Budgets

  … Define successful valid requests and latency buckets, including timeouts. Keep request-based and time-based availability calculations distinct …

• Behavioral Patterns II: Chain, Template, Iterator, Mediator, Memento, Visitor

  … records.length - valid.length }; } validate(record) { return true; } // default hook, can be overridden async save(records) { await db …

• Clean Error Handling

  … statusCode ValidationError : 400 NotFoundError : 404 ForbiddenError : 403 Rule 4: Handle errors in one central place In a web …

• Production Capstone and Interview Practice

  … The trailing hyphen in the shown prefix is allowed by the validation. The provider appends a uniqueness suffix …

• Design a URL Shortener

  … Protect users with rate limits, phishing scans and destination validation. Disabled links must invalidate quickly. Start with the …

• TypeScript Essentials

  … return "red"; } } badgeColor("pending"); // ❌ not a valid Status: typo caught! Narrowing: TypeScript tracks what a value can be …

• Reusable Modules and Clear Interfaces

  … variable "name" { type = string } variable "port" { type = number validation { condition = var.port = 1 && var.port <= 65535 && floor(var …

• REST API Design

  … Use status codes honestly mermaid flowchart TD R[Request] -- V{Valid input?} V -- no E400["400 Bad Request …

• Data Preparation and Model Training

  … Fit preprocessing steps on training data only, then apply those fitted steps to validation, test, and production inputs …

• Python Web APIs: FastAPI and Django

  … It's small, fast, async-friendly, and turns your type hints into validation and interactive API docs automatically …

• Scalable Frontend Architecture

  … Promise<Order { const response = await http.get( /orders/${id} ); return orderSchema.parse(response); // validate untrusted data at the …

• Developer Learning Plan and Document-Assistant Capstone

  … Measure retrieval hit rate, answer support, appropriate abstention, citation validity, and response time separately. Twenty questions are a …

• Domains, Load Balancers and HTTPS

  … Request a certificate for your domain, validate ownership by DNS, then attach it to the HTTPS listener. Check …

• AWS Security Building Blocks

  … Do not treat a JWT as trustworthy just because it looks like one; validation is required. Secrets Secrets …

• Train Your First Model from Scratch

  … Use separate training, validation, and test sets. Choose learning rate and other settings using validation data. Once you …

• ACID, Transactions & Locks

  … instantly current; it means the transaction moves valid state to valid state. Isolation anomalies you should recognize Anomaly …

• Domain-Driven Design: Tactical Patterns

  … small, immutable, self-validating ⭐ Value objects are the easiest tactical pattern to adopt, and remove a huge class …

• Safe AWS Deployments with IaC and CI/CD

  … Validate syntax and create a preview without executing it: bash aws cloudformation validate-template \ --template-body file://storage …

• AWS Data Pipelines in Plain Language

  … A Glue job runs transformations, such as converting raw CSV into typed, validated Parquet. A crawler can help …

• AI Evaluation, Safety, and Security

  … For tool use, test argument validation, authorization, retries, timeouts, and harmful actions. Measure latency and cost alongside quality …

• Your First Terraform Project

  … The output returns the created file's path. Initialize and preview bash terraform init terraform fmt terraform validate …

• Releases, Observability and Production Safety

  … Rotate secrets and validate configuration without exposing secret values. Walk through a failure and recovery The canary increases …

• Time, Consistency and Distributed Transactions

  … Use fencing tokens for stale owners and require the storage boundary to validate them. 3. Use a saga …

• System Design Interview Framework

  … describe the tests and metrics that would validate the design. Reserve time for the limits and the next …

• Database Relations & Foreign Keys

  … pair PRIMARY KEY(student id, course id) Application validation gives a friendly message; constraints protect the rule when …