ddd-anemic-domain-model

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Keywords: ddd-anemic-domain-model, domain-driven design, rich domain model, anemic domain model, anti-pattern, encapsulation, business logic, Aggregate Root, ESLint rule

Detects entities with only getters/setters and no business logic, enforcing the Rich Domain Model over the Anemic Domain Model anti-pattern.

Detects entities with only getters/setters and no business logic. This rule is part of eslint-plugin-modularity and helps enforce strong Domain-Driven Design (DDD) principles by encouraging behavior-rich entities.

Quick Summary

Aspect	Details
Severity	Medium (maintainability/design)
Auto-Fix	❌ No
Category	Modularity
ESLint MCP	✅ Optimized for ESLint MCP integration
Best For	Domain layers in DDD-based architectures
Suggestions	✅ 3 suggestions for remediation

The Anti-Pattern: Anemic Domain Model

Vulnerability/Issue: An Anemic Domain Model describes a domain layer where objects contain data but little or no logic. Instead, the logic is found in "Service" objects that manipulate the domain objects' state via getters and setters.

Risk: Anemic models lead to "Transaction Scripts" where business logic is fragmented across services, making it difficult to maintain invariants, increasing code duplication, and violating basic object-oriented principles like encapsulation.

Error Message Format

The rule provides LLM-optimized error messages with actionable architectural guidance:

📐 ARCHITECTURE | Anemic domain model detected in {{className}} | MEDIUM
   Fix: Add business logic methods to create a rich domain model | https://martinfowler.com/bliki/AnemicDomainModel.html

Message Components

Component	Purpose	Example
Domain Standard	Design benchmark	DDD Aggregate
Issue Description	Specific violation	`Class User has no business logic (only getters/setters)`
Severity & Impact	Design assessment	`MEDIUM`
Fix Instruction	Actionable remediation	`Add domain behavior methods to encapsulate state`
Technical Truth	Official reference	Anemic Domain Model

Rule Details

This rule identifies classes that don't satisfy the minimum requirement of business logic methods. It ignores standard Data Transfer Objects (DTOs) by default using configurable naming patterns.

Why This Matters

Issue	Impact	Solution
💊 Encapsulation	State can be corrupted from anywhere	Move logic into the entity and make setters private/protected
🧩 Duplication	Logic repeated in multiple services	Consolidate logic as methods on the domain model
🛠️ Maintainability	Hard to find where behavior resides	Behavior lives with the data it operates on

Configuration

Option	Type	Default	Description
`minBusinessMethods`	`number`	`1`	Minimum methods required to not be considered anemic
`ignoreDtos`	`boolean`	`true`	Whether to ignore classes matching DTO patterns
`dtoPatterns`	`string[]`	`['DTO', 'Dto', 'Data', 'Request', 'Response', 'Payload']`	Naming patterns used to identify DTOs/Data objects

Examples

❌ Incorrect

// Anemic Domain Model (Logic-less Entity)
class BankAccount {
  private balance: number = 0;

  public getBalance(): number {
    return this.balance;
  }

  public setBalance(amount: number): void {
    this.balance = amount;
  }
}

// Logic is forced into an external service
class BankService {
  withdraw(account: BankAccount, amount: number) {
    if (account.getBalance() >= amount) {
      account.setBalance(account.getBalance() - amount);
    }
  }
}

✅ Correct

// Rich Domain Model (Encapsulated Behavior)
class BankAccount {
  private balance: number = 0;

  public withdraw(amount: number): void {
    if (amount <= 0) throw new Error('Amount must be positive');
    if (this.balance < amount) throw new Error('Insufficient funds');

    this.balance -= amount;
  }

  public getBalance(): number {
    return this.balance;
  }
}

Configuration Examples

Enforce Stricter Models

{
  rules: {
    'modularity/ddd-anemic-domain-model': ['error', {
      minBusinessMethods: 2,
      dtoPatterns: ['Model', 'Entity'] // Also ignore these patterns
    }]
  }
}