New Entity

Create a new domain entity following DDD principles with its repository interface.

IMPORTANT - Code Quality: Before generating code, fetch the latest Uber Go Style Guide:

fetch_webpage("https://github.com/uber-go/guide/blob/master/style.md", "latest Go best practices")

This ensures all generated code follows current production standards.

What to Create:

1. •

   Ask the user:

   • •Which domain/bounded context? (e.g., "user", "order", "product")
   • •Entity name (e.g., User, Product, Order)
   • •Fields/attributes with types
   • •Business rules/validations
   • •Is it an aggregate root or entity?
   • •Value objects needed?
2. •

   Create entity in internal/[domain]/domain/entity.go (or [entity_name].go if multiple entities):

   • •Define struct with fields
   • •Add constructor (New[Entity]) with validation
   • •Add business logic methods
   • •Add domain validations
   • •Use value objects where appropriate
   • •NO infrastructure dependencies
3. •

   Create repository interface in internal/[domain]/domain/repository.go:

   • •Define persistence contract
   • •Common methods: Save, FindByID, Update, Delete, List
   • •Use domain types only
   • •Return domain errors
4. •

   Create unit tests in test/unit/[domain]/entity_test.go:

   • •Test entity creation (valid and invalid)
   • •Test business logic methods
   • •Test validations
   • •Use table-driven tests
5. •

   Create value objects (if needed) in internal/shared/valueobject/[value_object_name].go:

   • •Email, Money, Address, etc.
   • •Immutable
   • •Self-validating
   • •With unit tests

DDD Principles:

• •Entities have identity (ID field)
• •Rich domain model (behavior, not just data)
• •Encapsulation (use methods, not public setters)
• •Invariants are always protected
• •Use ubiquitous language
• •Value objects for concepts without identity

Example Entity Structure:

type User struct {
    id        uuid.UUID
    email     Email // value object
    name      string
    createdAt time.Time
}

func NewUser(email, name string) (*User, error) {
    // validation
    // business rules
    return &User{...}, nil
}

func (u *User) ChangeName(newName string) error {
    // validation
    // business rules
}

Be concise and follow Go best practices.