Java Spring

Java/Spring Boot Conventions

Stack Overview

• Framework: Spring Boot 3.2.x with Spring MVC
• Java Version: Java 21
• Build: Maven
• Database: MongoDB (Spring Data MongoDB) or PostgreSQL (Spring Data JPA)
• Serialization: Jackson with SNAKE_CASE property naming

Project Structure

src/main/java/io/drizzl/platform/{service}/
├── config/         # Spring beans, configuration classes
├── temporal/       # Workflow and activity implementations
├── service/        # Core business logic
├── repository/     # Data access layer
├── web/            # REST controllers, webhook endpoints
├── model/          # Domain models and DTOs
└── {platform}/     # Platform-specific integrations (e.g., shopify/)

Critical Patterns

API Endpoint Parameter Pattern

CRITICAL: Always use path parameters for database queries, NOT header parameters!

// CORRECT - Path parameter for database queries
@PostMapping("/apps/{app_id}/some-operation")
public ResponseEntity<?> someOperation(
    @RequestHeader("X-Violet-Token") String token,           // Auth only
    @RequestHeader("X-Violet-App-Secret") String appSecret,  // Auth only
    @RequestHeader("X-Violet-App-Id") Integer appIdHeader,   // Auth only
    @PathVariable("app_id") Integer appId,                   // USE THIS for DB
    @RequestBody SomeRequest request) {
    repository.findByAppId(appId);  // Use path parameter
}

// WRONG - Using header for database queries
@PostMapping("/some-operation")
public ResponseEntity<?> someOperation(
    @RequestHeader("X-Violet-App-Id") Integer appId) {
    repository.findByAppId(appId);  // Security risk!
}

Standard Violet Endpoint Pattern:

POST /v1/{service}/apps/{app_id}/endpoint-name
  Headers: X-Violet-Token, X-Violet-App-Secret, X-Violet-App-Id (authentication)
  Path: app_id (target for database operations)
  Query: Optional parameters (filters, dry_run, etc.)
  Body: Request payload

Null Safety for Partial Updates

Always verify nested fields are not null before accessing:

// WRONG - Assumes field is always present
if (updateDetails.getChanges() != null) {
    input.put("value", updateDetails.getChanges().getValue().getNewValue());
}

// CORRECT - Check nested field first
if (updateDetails.getChanges() != null
    && updateDetails.getChanges().getValue() != null) {
    input.put("value", updateDetails.getChanges().getValue().getNewValue());
}

Database Timing Pass-Through Pattern

Fresh database queries immediately after save can retrieve stale data:

// CORRECT - Pass-through pattern
Entity updated = repository.save(entity);
processWithUpdatedData(updated);  // Use passed object, not fresh query

MongoDB Conventions

• Use @Document annotation instead of @Entity
• Use @Field instead of @Column
• Repository extends MongoRepository
• Use @CreatedDate / @LastModifiedDate for timestamps
• Snake_case field naming with @Field annotations

@Document(collection = "my_collection")
public class MyDocument {
    @Id
    private String id;

    @Field("app_id")
    private Integer appId;

    @CreatedDate
    @Field("created_at")
    private Instant createdAt;
}

Jackson Configuration

spring.jackson.property-naming-strategy=SNAKE_CASE

Encryption

• Local/Development: AES encryption with test keys
• Production: AWS KMS (when violet.env=production)

security.aes.key=${AES_KEY:defaultKey}
security.aes.vector=${AES_VECTOR:defaultVector}

Build & Run

mvn clean install spring-boot:run