Data Model

Data Model Generation Command

Current Time: !date PostgreSQL: !psql --version

Create comprehensive Entity Relationship Diagrams (ERDs) and data documentation for the current project.

Objective

Generate complete data model documentation including:

1. Database schemas - Tables, relationships, constraints, indexes
2. Service layer models - DTOs, domain models, business logic data structures
3. UI data structures - Component props, state management, data flows

Output Location

Save all documentation to: ./docs/architecture/data-model.md (relative to current project directory)

Important: Auto-create the ./docs/architecture/ directory if it doesn't exist.

Discovery Phase

Before generating documentation, perform comprehensive project analysis:

1. Database Technology Detection

   • Scan for Prisma schema files (prisma/schema.prisma)
   • Check for TypeORM entities (*.entity.ts, decorators like @Entity)
   • Look for Sequelize models (models/*.js, sequelize.define)
   • Find Mongoose schemas (*.model.ts, mongoose.Schema)
   • Detect raw SQL files (*.sql, migrations/*.sql)
   • Check for Django models (models.py)
   • Look for SQLAlchemy models (Python Base.metadata)

2. Backend Framework Detection

   • Next.js (check next.config.js, API routes in app/api/ or pages/api/)
   • Express.js (check package.json for express, look for app.js or server.js)
   • FastAPI (check requirements.txt, main.py with @app decorators)
   • Django (check settings.py, urls.py)
   • NestJS (check for @Module, @Controller decorators)

3. Frontend State Management Detection

   • Redux (check for createSlice, configureStore)
   • Zustand (check for create from zustand)
   • Context API (check for createContext, useContext)
   • React Query (check for useQuery, useMutation)
   • MobX (check for makeObservable, @observable)
   • Jotai (check for atom from jotai)

4. Service Layer Patterns

   • Repository pattern (look for *.repository.ts)
   • Service pattern (look for *.service.ts)
   • Controller pattern (look for *.controller.ts)
   • Use cases (look for *.usecase.ts)

Generation Process

Create a comprehensive single-file documentation at ./docs/architecture/data-model.md with the following structure:

Data Model Documentation

Generated on: [DATE] Project: [PROJECT_NAME] Tech Stack: [AUTO-DETECTED STACK]

Table of Contents

1. Database Schema ERD
2. Service Layer Models
3. UI Data Structures
4. End-to-End Data Flow

1. Database Schema ERD

Overview

[Brief description of the database architecture]

Entity Relationship Diagram

erDiagram
    %% Generate complete ERD with:
    %% - All tables/entities
    %% - Column definitions with types
    %% - Relationships (one-to-one, one-to-many, many-to-many)
    %% - Foreign keys
    %% - Cardinality

    USER ||--o{ ORDER : places
    USER {
        uuid id PK
        string email UK
        string password_hash
        timestamp created_at
        timestamp updated_at
    }

    ORDER ||--|{ ORDER_ITEM : contains
    ORDER {
        uuid id PK
        uuid user_id FK
        string status
        decimal total_amount
        timestamp created_at
    }

    %% ... continue for all entities

Table Definitions

[Table 1 Name]

• Purpose: [Brief description]
• Columns:
  • id (UUID, PRIMARY KEY) - Unique identifier
  • email (VARCHAR(255), UNIQUE, NOT NULL) - User email address
  • created_at (TIMESTAMP, DEFAULT NOW()) - Creation timestamp
  • [... all columns with types and constraints]
• Indexes:
  • idx_email on email (unique)
  • idx_created_at on created_at
• Foreign Keys:
  • None / [list foreign keys]
• Notes: [Any special considerations]

[Repeat for all tables]

2. Service Layer Models

Overview

[Description of service layer architecture]

Data Transfer Objects (DTOs)

Request DTOs

CreateUserDTO

interface CreateUserDTO {
  email: string; // Valid email format
  password: string; // Min 8 chars, 1 uppercase, 1 number
  firstName?: string;
  lastName?: string;
}

Validation Rules:

• email: Required, valid email format
• password: Required, min 8 characters, must contain uppercase, number
• firstName: Optional, max 50 characters
• lastName: Optional, max 50 characters

[Continue for all DTOs]

Response DTOs

UserResponseDTO

interface UserResponseDTO {
  id: string;
  email: string;
  firstName: string | null;
  lastName: string | null;
  createdAt: string; // ISO 8601 format
  updatedAt: string;
}

[Continue for all response DTOs]

Domain Models

User Domain Model

class User {
  private id: string;
  private email: string;
  private passwordHash: string;

  // Business logic methods
  public verifyPassword(plaintext: string): boolean;
  public updateEmail(newEmail: string): void;
}

Business Rules:

• Email must be unique across system
• Password changes require current password verification
• Deleted users retain data for 30 days (soft delete)

[Continue for all domain models]

3. UI Data Structures

Overview

[Description of frontend data architecture]

Component Props

UserProfile Component

interface UserProfileProps {
  user: {
    id: string;
    email: string;
    firstName: string | null;
    lastName: string | null;
  };
  onUpdate: (data: Partial<UpdateUserDTO>) => Promise<void>;
  isLoading: boolean;
}

[Continue for major components]

State Management Schemas

User State (Redux/Zustand/etc.)

interface UserState {
  currentUser: User | null;
  isAuthenticated: boolean;
  isLoading: boolean;
  error: string | null;
}

Actions:

• loginUser(credentials) - Authenticate user
• logoutUser() - Clear session
• updateUserProfile(data) - Update user data

[Continue for all state slices]

Form Schemas

User Registration Form

interface RegistrationFormSchema {
  email: string;
  password: string;
  confirmPassword: string;
  firstName?: string;
  lastName?: string;
  agreeToTerms: boolean;
}

Validation:

• Client-side: Zod/Yup schema validation
• Server-side: DTO validation
• Real-time field validation on blur

4. End-to-End Data Flow

Overview

Complete data flow from database through API to UI and back.

Data Flow Diagram

flowchart TD
    DB[(Database)]
    REPO[Repository Layer]
    SERVICE[Service Layer]
    CONTROLLER[Controller/API]
    STATE[State Management]
    UI[UI Components]

    DB -->|Raw Data| REPO
    REPO -->|Domain Models| SERVICE
    SERVICE -->|DTOs| CONTROLLER
    CONTROLLER -->|JSON Response| STATE
    STATE -->|Props| UI

    UI -->|User Action| STATE
    STATE -->|API Call| CONTROLLER
    CONTROLLER -->|Validate & Process| SERVICE
    SERVICE -->|Business Logic| REPO
    REPO -->|SQL/ORM| DB

    style DB fill:#f9f,stroke:#333,stroke-width:2px
    style UI fill:#bbf,stroke:#333,stroke-width:2px

Example Flow: User Registration

1. User submits registration form (UI)

// Component
const handleSubmit = async (formData: RegistrationFormSchema) => {
  await registerUser(formData);
};

2. API call dispatched (State Management)

// Action/Mutation
const registerUser = async (data: CreateUserDTO) => {
  const response = await fetch("/api/users/register", {
    method: "POST",
    body: JSON.stringify(data),
  });
  return response.json();
};

3. API endpoint receives request (Controller)

// POST /api/users/register
async function handleRegister(req: Request) {
  const dto = validateDTO(CreateUserDTO, req.body);
  const user = await userService.createUser(dto);
  return UserResponseDTO.from(user);
}

4. Business logic executed (Service)

// UserService
async createUser(dto: CreateUserDTO): Promise<User> {
  // Hash password
  const passwordHash = await bcrypt.hash(dto.password, 10);

  // Create user via repository
  const user = await userRepository.create({
    email: dto.email,
    passwordHash,
    firstName: dto.firstName,
    lastName: dto.lastName
  });

  return user;
}

5. Database operation (Repository)

// UserRepository
async create(data: CreateUserData): Promise<User> {
  return await db.user.create({
    data: {
      id: uuid(),
      email: data.email,
      passwordHash: data.passwordHash,
      firstName: data.firstName,
      lastName: data.lastName,
      createdAt: new Date(),
      updatedAt: new Date()
    }
  });
}

Data Transformations:

• UI Form → CreateUserDTO (client-side validation)
• CreateUserDTO → Domain Model (service layer)
• Domain Model → Database Entity (repository layer)
• Database Entity → Domain Model (on read)
• Domain Model → UserResponseDTO (API response)
• UserResponseDTO → UI State (state management)

[Repeat for other critical flows: Authentication, CRUD operations, etc.]

Data Validation Strategy

Client-Side Validation

• Form validation using Zod/Yup/Joi
• Real-time feedback on input
• TypeScript type safety

Server-Side Validation

• DTO validation (class-validator or similar)
• Business rule validation in service layer
• Database constraint validation

Database Constraints

• Primary keys (UUID)
• Foreign keys (referential integrity)
• Unique constraints
• Check constraints
• Not null constraints

Notes and Considerations

Performance Optimization

• Database indexes on frequently queried columns
• Lazy loading for large datasets
• Pagination for list endpoints
• Caching strategy (Redis, etc.)

Security Considerations

• Password hashing (bcrypt, argon2)
• SQL injection prevention (ORM parameterization)
• XSS prevention (output sanitization)
• CSRF protection
• Rate limiting on API endpoints

Future Enhancements

• [List planned changes to data model]
• [Migrations planned]
• [New entities/features]

Output Format Instructions

1. Use Mermaid syntax for all diagrams (ERD and flowcharts)
2. Include TypeScript interfaces where applicable (even for non-TS projects, use TS syntax for clarity)
3. Document all relationships between entities
4. Include validation rules for all DTOs and forms
5. Add notes for complex business logic or special cases
6. Be comprehensive - include all tables, models, and major components
7. Keep it updated - regenerate when schema changes

Technology-Specific Instructions

For Prisma Projects

• Parse prisma/schema.prisma file
• Extract all models with fields, relations, indexes
• Document enums and custom types

For TypeORM Projects

• Scan for *.entity.ts files
• Parse decorators: @Entity, @Column, @ManyToOne, etc.
• Document relationships and cascade options

For Sequelize Projects

• Find model definitions in models/ directory
• Parse sequelize.define() calls
• Document associations (hasMany, belongsTo, etc.)

For Mongoose Projects

• Scan for *.model.ts or *.schema.ts files
• Parse mongoose.Schema() definitions
• Document virtual fields and methods

For Django Projects

• Parse models.py files
• Extract Django model classes with fields
• Document relationships (ForeignKey, ManyToMany, etc.)

For Next.js Projects

• Check both App Router (app/api/) and Pages Router (pages/api/)
• Document Server Components data fetching
• Include Client Component state patterns

Execution Steps

1. Create ./docs/architecture/ directory if it doesn't exist
2. Scan project for database schema files
3. Identify all entities/tables
4. Parse relationships and constraints
5. Scan for service layer patterns
6. Identify DTOs and domain models
7. Scan frontend for component props and state management
8. Generate comprehensive single-file documentation
9. Save to ./docs/architecture/data-model.md
10. Confirm successful creation

Success Criteria

✅ Single comprehensive file created at ./docs/architecture/data-model.md ✅ All database entities documented with Mermaid ERD ✅ All service layer models documented (DTOs, domain models) ✅ All UI data structures documented (props, state) ✅ End-to-end data flow documented with diagrams ✅ Validation rules included for all data structures ✅ Technology stack auto-detected and documented ✅ File is well-organized and easy to navigate

$ARGUMENTS

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