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intermediatePhase ·

Validation

Define validation rules for all request fields.

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Validation Design

Validation Rules

Field Rules
name Required, 2-100 chars
price Required, positive
email Valid format
sku Required, unique pattern

Error Response

{
  "error": "VALIDATION_ERROR",
  "details": [
    {"field": "name", "message": "Required, 2-100 chars"},
    {"field": "price", "message": "Must be positive"}
  ]
}

Key Points

  • Understanding API Design: Validation is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

API Best Practices

Design Principles

  • Use nouns, not verbs
  • Plural resource names
  • Consistent naming conventions
  • Proper HTTP status codes

Versioning

  • URI versioning (/v1/resource)
  • Header versioning
  • Deprecation policy

Documentation

  • OpenAPI/Swagger specs
  • Request/Response examples
  • Error code documentation
  • Rate limit documentation

Key Points

  • Understanding API Design: Validation is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0/3solved
Implement API Design: Validation

Design and implement a solution for API Design: Validation in a backend system. Consider scalability, error handling, and production readiness.

Solution
// API Design: Validation implementation
// Key aspects: validation, error handling, logging, testing

public class APIDesignValidation {
    // Production-ready implementation
}
API Design: Validation Edge Cases

Identify and handle edge cases for API Design: Validation. What happens under high load, with invalid input, or during failures?

Solution
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
API Design: Validation Testing Strategy

Write a testing strategy for API Design: Validation. Include unit tests, integration tests, and performance tests.

Solution
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. Validation errors return?

Question 1 options

2. Validation should happen?

Question 2 options

3. What is the primary purpose of API Design: Validation?

Question 3 options

4. What is a common mistake when implementing API Design: Validation?

Question 4 options

Flashcards

Question

Validation error status?

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Answer

400 or 422

Question

Validate where?

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Answer

Both client and server

Question

What is API Design: Validation?

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Answer

API Design: Validation is a key concept in backend development.

Question

When to use API Design: Validation?

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Answer

Use API Design: Validation when building production systems that require reliability, scalability, and maintainability.

Question

API Design: Validation best practices

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Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1.Define validation rules for each field
  • 2.Return 400/422 with detailed errors
  • 3.Validate on both client and server
  • 4.Include field-level error messages

Interview Tips

  • •Design validation rules
  • •Handle validation errors

Cheat Sheet

Validation

  • Rules: per field (required, min, max)
  • Errors: 400/422 with details
  • Validate: client + server
  • Response: field-level messages