Generate REST API

Automatically generate comprehensive RESTful API implementations from schema definitions with proper routing, validation, error handling, authentication, pagination, and OpenAPI documentation following industry best practices.

When to Use This Command

Use /generate-rest-api when you need to:

• Build CRUD APIs quickly with consistent patterns
• Create microservices with RESTful interfaces
• Generate APIs from database schemas or models
• Implement standardized API patterns across projects
• Support multiple client applications (web, mobile, IoT)
• Build public APIs with comprehensive documentation

DON'T use this when:

• Building real-time applications (consider WebSocket/gRPC)
• Internal services need maximum performance (consider gRPC)
• Complex event-driven architectures (consider event streaming)
• GraphQL would better serve client needs

Design Decisions

This command implements OpenAPI-first design as the primary approach because:

• Contract-first development ensures consistency
• Auto-generates server stubs and client SDKs
• Provides interactive API documentation
• Enables API mocking during development
• Supports multiple framework implementations
• Industry-standard specification format

Alternative considered: Code-first with annotations

• Faster initial development
• Tighter coupling to implementation
• Less portable across frameworks
• Recommended for rapid prototyping

Alternative considered: GraphQL

• More flexible client queries
• Reduced over/under-fetching
• Higher complexity
• Recommended for complex client needs

Prerequisites

Before running this command:

1. Define your data models and relationships
2. Choose target framework (Express, FastAPI, NestJS, etc.)
3. Select database technology
4. Determine authentication requirements
5. Plan API versioning strategy

Implementation Process

Step 1: Define OpenAPI Specification

Create comprehensive API contracts with schemas, endpoints, and examples.

Step 2: Generate Server Stubs

Build framework-specific implementations from OpenAPI specs.

Step 3: Implement Business Logic

Add controllers, services, and data access layers.

Step 4: Add Middleware

Configure authentication, validation, rate limiting, and CORS.

Step 5: Generate Documentation

Create interactive docs, client SDKs, and Postman collections.

Output Format

The command generates:

• openapi.yaml - Complete API specification
• src/controllers/ - Request handlers with business logic
• src/routes/ - RESTful endpoint definitions
• src/models/ - Data models and schemas
• src/middleware/ - Auth, validation, rate limiting
• src/services/ - Business logic layer
• tests/ - Integration and unit tests
• docs/ - API documentation and examples

Code Examples

Example 1: E-commerce API with Express.js and TypeScript

# openapi.yaml
openapi: 3.0.0
info:
  title: E-commerce API
  version: 1.0.0
  description: RESTful API for e-commerce platform

servers:
  - url: https://api.example.com/v1
    description: Production server
  - url: http://localhost:3000/v1
    description: Development server

components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT

  schemas:
    Product:
      type: object
      required:
        - name
        - price
        - inventory
      properties:
        id:
          type: string
          format: uuid
          readOnly: true
        name:
          type: string
          minLength: 1
          maxLength: 200
        description:
          type: string
          maxLength: 2000
        price:
          type: number
          minimum: 0
          multipleOf: 0.01
        inventory:
          type: integer
          minimum: 0
        category:
          type: string
          enum: [electronics, clothing, food, books, other]
        images:
          type: array
          items:
            type: string
            format: uri
        metadata:
          type: object
          additionalProperties:
            type: string
        createdAt:
          type: string
          format: date-time
          readOnly: true
        updatedAt:
          type: string
          format: date-time
          readOnly: true

    Error:
      type: object
      required:
        - code
        - message
      properties:
        code:
          type: string
        message:
          type: string
        details:
          type: object

    PaginatedProducts:
      type: object
      properties:
        data:
          type: array
          items:
            $ref: '#/components/schemas/Product'
        pagination:
          type: object
          properties:
            total:
              type: integer
            page:
              type: integer
            perPage:
              type: integer
            totalPages:
              type: integer
        links:
          type: object
          properties:
            self:
              type: string
            next:
              type: string
            prev:
              type: string
            first:
              type: string
            last:
              type: string

paths:
  /products:
    get:
      summary: List products
      operationId: listProducts
      tags:
        - Products
      parameters:
        - name: page
          in: query
          schema:
            type: integer
            default: 1
            minimum: 1
        - name: perPage
          in: query
          schema:
            type: integer
            default: 20
            minimum: 1
            maximum: 100
        - name: category
          in: query
          schema:
            type: string
            enum: [electronics, clothing, food, books, other]
        - name: minPrice
          in: query
          schema:
            type: number
            minimum: 0
        - name: maxPrice
          in: query
          schema:
            type: number
            minimum: 0
        - name: search
          in: query
          schema:
            type: string
        - name: sort
          in: query
          schema:
            type: string
            enum: [name, price, createdAt]
        - name: order
          in: query
          schema:
            type: string
            enum: [asc, desc]
            default: asc
      responses:
        '200':
          description: Products retrieved successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaginatedProducts'
        '400':
          description: Invalid request parameters
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'

    post:
      summary: Create product
      operationId: createProduct
      tags:
        - Products
      security:
        - bearerAuth: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Product'
      responses:
        '201':
          description: Product created successfully
          headers:
            Location:
              schema:
                type: string
                format: uri
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Product'
        '400':
          description: Invalid product data
        '401':
          description: Unauthorized
        '422':
          description: Validation error

  /products/{productId}:
    parameters:
      - name: productId
        in: path
        required: true
        schema:
          type: string
          format: uuid

    get:
      summary: Get product by ID
      operationId: getProduct
      tags:
        - Products
      responses:
        '200':
          description: Product retrieved successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Product'
        '404':
          description: Product not found

    put:
      summary: Update product
      operationId: updateProduct
      tags:
        - Products
      security:
        - bearerAuth: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Product'
      responses:
        '200':
          description: Product updated successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Product'
        '400':
          description: Invalid product data
        '401':
          description: Unauthorized
        '404':
          description: Product not found

    patch:
      summary: Partial update product
      operationId: patchProduct
      tags:
        - Products
      security:
        - bearerAuth: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              minProperties: 1
      responses:
        '200':
          description: Product updated successfully

    delete:
      summary: Delete product
      operationId: deleteProduct
      tags:
        - Products
      security:
        - bearerAuth: []
      responses:
        '204':
          description: Product deleted successfully
        '401':
          description: Unauthorized
        '404':
          description: Product not found

// src/app.ts - Express application setup
import express, { Application } from 'express';
import helmet from 'helmet';
import cors from 'cors';
import compression from 'compression';
import morgan from 'morgan';
import swaggerUi from 'swagger-ui-express';
import { rateLimit } from 'express-rate-limit';
import { errorHandler } from './middleware/errorHandler';
import { notFoundHandler } from './middleware/notFoundHandler';
import { authMiddleware } from './middleware/auth';
import { validationMiddleware } from './middleware/validation';
import { productRouter } from './routes/products';
import { loadOpenAPISpec } from './utils/openapi';

export class App {
    public app: Application;

    constructor() {
        this.app = express();
        this.initializeMiddleware();
        this.initializeRoutes();
        this.initializeErrorHandling();
    }

    private initializeMiddleware(): void {
        // Security middleware
        this.app.use(helmet());
        this.app.use(cors({
            origin: process.env.ALLOWED_ORIGINS?.split(',') || '*',
            credentials: true
        }));

        // Rate limiting
        const limiter = rateLimit({
            windowMs: 15 * 60 * 1000, // 15 minutes
            max: 100, // limit each IP to 100 requests per windowMs
            standardHeaders: true,
            legacyHeaders: false,
            message: 'Too many requests from this IP'
        });
        this.app.use('/api/', limiter);

        // Body parsing
        this.app.use(express.json({ limit: '10mb' }));
        this.app.use(express.urlencoded({ extended: true, limit: '10mb' }));

        // Compression
        this.app.use(compression());

        // Logging
        this.app.use(morgan('combined'));

        // API Documentation
        const openAPISpec = loadOpenAPISpec();
        this.app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(openAPISpec));
    }

    private initializeRoutes(): void {
        // Health check
        this.app.get('/health', (req, res) => {
            res.json({ status: 'healthy', timestamp: new Date().toISOString() });
        });

        // API routes
        this.app.use('/v1/products', productRouter);

        // Catch-all for API routes
        this.app.all('/v1/*', notFoundHandler);
    }

    private initializeErrorHandling(): void {
        this.app.use(errorHandler);
    }
}

// src/controllers/productController.ts
import { Request, Response, NextFunction } from 'express';
import { ProductService } from '../services/productService';
import { PaginationParams, FilterParams } from '../types';
import { ApiError } from '../utils/ApiError';

export class ProductController {
    constructor(private productService: ProductService) {}

    async listProducts(
        req: Request,
        res: Response,
        next: NextFunction
    ): Promise<void> {
        try {
            const pagination: PaginationParams = {
                page: parseInt(req.query.page as string) || 1,
                perPage: parseInt(req.query.perPage as string) || 20
            };

            const filters: FilterParams = {
                category: req.query.category as string,
                minPrice: parseFloat(req.query.minPrice as string),
                maxPrice: parseFloat(req.query.maxPrice as string),
                search: req.query.search as string,
                sort: req.query.sort as string || 'createdAt',
                order: req.query.order as 'asc' | 'desc' || 'desc'
            };

            const result = await this.productService.listProducts(
                pagination,
                filters
            );

            // Add HATEOAS links
            const baseUrl = `${req.protocol}://${req.get('host')}${req.baseUrl}`;
            const links = this.generatePaginationLinks(
                baseUrl,
                pagination,
                result.pagination.totalPages
            );

            res.json({
                ...result,
                links
            });
        } catch (error) {
            next(error);
        }
    }

    async getProduct(
        req: Request,
        res: Response,
        next: NextFunction
    ): Promise<void> {
        try {
            const { productId } = req.params;
            const product = await this.productService.getProduct(productId);

            if (!product) {
                throw new ApiError(404, 'Product not found');
            }

            // Add HATEOAS links
            const links = {
                self: `${req.protocol}://${req.get('host')}${req.originalUrl}`,
                update: {
                    href: `${req.protocol}://${req.get('host')}${req.originalUrl}`,
                    method: 'PUT'
                },
                delete: {
                    href: `${req.protocol}://${req.get('host')}${req.originalUrl}`,
                    method: 'DELETE'
                }
            };

            res.json({
                ...product,
                _links: links
            });
        } catch (error) {
            next(error);
        }
    }

    async createProduct(
        req: Request,
        res: Response,
        next: NextFunction
    ): Promise<void> {
        try {
            const product = await this.productService.createProduct(req.body);
            const location = `${req.protocol}://${req.get('host')}${req.baseUrl}/${product.id}`;

            res.status(201)
               .location(location)
               .json(product);
        } catch (error) {
            next(error);
        }
    }

    async updateProduct(
        req: Request,
        res: Response,
        next: NextFunction
    ): Promise<void> {
        try {
            const { productId } = req.params;
            const product = await this.productService.updateProduct(
                productId,
                req.body
            );

            if (!product) {
                throw new ApiError(404, 'Product not found');
            }

            res.json(product);
        } catch (error) {
            next(error);
        }
    }

    async patchProduct(
        req: Request,
        res: Response,
        next: NextFunction
    ): Promise<void> {
        try {
            const { productId } = req.params;
            const product = await this.productService.patchProduct(
                productId,
                req.body
            );

            if (!product) {
                throw new ApiError(404, 'Product not found');
            }

            res.json(product);
        } catch (error) {
            next(error);
        }
    }

    async deleteProduct(
        req: Request,
        res: Response,
        next: NextFunction
    ): Promise<void> {
        try {
            const { productId } = req.params;
            const deleted = await this.productService.deleteProduct(productId);

            if (!deleted) {
                throw new ApiError(404, 'Product not found');
            }

            res.status(204).send();
        } catch (error) {
            next(error);
        }
    }

    private generatePaginationLinks(
        baseUrl: string,
        pagination: PaginationParams,
        totalPages: number
    ): Record<string, string> {
        const links: Record<string, string> = {
            self: `${baseUrl}?page=${pagination.page}&perPage=${pagination.perPage}`
        };

        if (pagination.page > 1) {
            links.first = `${baseUrl}?page=1&perPage=${pagination.perPage}`;
            links.prev = `${baseUrl}?page=${pagination.page - 1}&perPage=${pagination.perPage}`;
        }

        if (pagination.page < totalPages) {
            links.next = `${baseUrl}?page=${pagination.page + 1}&perPage=${pagination.perPage}`;
            links.last = `${baseUrl}?page=${totalPages}&perPage=${pagination.perPage}`;
        }

        return links;
    }
}

// src/middleware/validation.ts
import { Request, Response, NextFunction } from 'express';
import Joi from 'joi';
import { ApiError } from '../utils/ApiError';

export function validate(schema: Joi.Schema) {
    return (req: Request, res: Response, next: NextFunction) => {
        const { error, value } = schema.validate(req.body, {
            abortEarly: false,
            stripUnknown: true
        });

        if (error) {
            const errors = error.details.map(detail => ({
                field: detail.path.join('.'),
                message: detail.message
            }));

            throw new ApiError(422, 'Validation error', errors);
        }

        req.body = value;
        next();
    };
}

// src/schemas/product.schema.ts
import Joi from 'joi';

export const productSchema = {
    create: Joi.object({
        name: Joi.string().min(1).max(200).required(),
        description: Joi.string().max(2000),
        price: Joi.number().min(0).multiple(0.01).required(),
        inventory: Joi.number().integer().min(0).required(),
        category: Joi.string().valid(
            'electronics',
            'clothing',
            'food',
            'books',
            'other'
        ),
        images: Joi.array().items(Joi.string().uri()),
        metadata: Joi.object().pattern(Joi.string(), Joi.string())
    }),

    update: Joi.object({
        name: Joi.string().min(1).max(200),
        description: Joi.string().max(2000),
        price: Joi.number().min(0).multiple(0.01),
        inventory: Joi.number().integer().min(0),
        category: Joi.string().valid(
            'electronics',
            'clothing',
            'food',
            'books',
            'other'
        ),
        images: Joi.array().items(Joi.string().uri()),
        metadata: Joi.object().pattern(Joi.string(), Joi.string())
    }).min(1),

    query: Joi.object({
        page: Joi.number().integer().min(1).default(1),
        perPage: Joi.number().integer().min(1).max(100).default(20),
        category: Joi.string().valid(
            'electronics',
            'clothing',
            'food',
            'books',
            'other'
        ),
        minPrice: Joi.number().min(0),
        maxPrice: Joi.number().min(0),
        search: Joi.string(),
        sort: Joi.string().valid('name', 'price', 'createdAt'),
        order: Joi.string().valid('asc', 'desc').default('asc')
    })
};

Example 2: FastAPI Implementation with Python

# main.py - FastAPI application
from fastapi import FastAPI, HTTPException, Query, Depends, status
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.trustedhost import TrustedHostMiddleware
from fastapi.middleware.gzip import GZipMiddleware
from fastapi.responses import JSONResponse
from slowapi import Limiter, _rate_limit_exceeded_handler
from slowapi.util import get_remote_address
from slowapi.errors import RateLimitExceeded
from typing import Optional, List
from datetime import datetime
from pydantic import BaseModel, Field, validator
import uvicorn

# Create rate limiter
limiter = Limiter(key_func=get_remote_address)

# Create FastAPI app
app = FastAPI(
    title="E-commerce API",
    version="1.0.0",
    description="RESTful API for e-commerce platform",
    docs_url="/api-docs",
    redoc_url="/redoc"
)

# Add rate limit handler
app.state.limiter = limiter
app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)

# Add middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)
app.add_middleware(GZipMiddleware, minimum_size=1000)
app.add_middleware(
    TrustedHostMiddleware,
    allowed_hosts=["*.example.com", "localhost"]
)

# Pydantic models
class ProductBase(BaseModel):
    name: str = Field(..., min_length=1, max_length=200)
    description: Optional[str] = Field(None, max_length=2000)
    price: float = Field(..., gt=0, multiple_of=0.01)
    inventory: int = Field(..., ge=0)
    category: Optional[str] = Field(
        None,
        regex="^(electronics|clothing|food|books|other)$"
    )
    images: Optional[List[str]] = []
    metadata: Optional[dict] = {}

    @validator('price')
    def validate_price(cls, v):
        if v <= 0:
            raise ValueError('Price must be positive')
        return round(v, 2)

class ProductCreate(ProductBase):
    pass

class ProductUpdate(BaseModel):
    name: Optional[str] = Field(None, min_length=1, max_length=200)
    description: Optional[str] = Field(None, max_length=2000)
    price: Optional[float] = Field(None, gt=0, multiple_of=0.01)
    inventory: Optional[int] = Field(None, ge=0)
    category: Optional[str] = None
    images: Optional[List[str]] = None
    metadata: Optional[dict] = None

class Product(ProductBase):
    id: str
    created_at: datetime
    updated_at: datetime

    class Config:
        orm_mode = True

class PaginationParams(BaseModel):
    page: int = Query(1, ge=1, description="Page number")
    per_page: int = Query(20, ge=1, le=100, description="Items per page")

class FilterParams(BaseModel):
    category: Optional[str] = Query(None, regex="^(electronics|clothing|food|books|other)$")
    min_price: Optional[float] = Query(None, ge=0)
    max_price: Optional[float] = Query(None, ge=0)
    search: Optional[str] = Query(None, max_length=100)
    sort: str = Query("created_at", regex="^(name|price|created_at)$")
    order: str = Query("desc", regex="^(asc|desc)$")

class PaginatedResponse(BaseModel):
    data: List[Product]
    pagination: dict
    links: dict

# Routes
@app.get("/health")
async def health_check():
    """Health check endpoint."""
    return {
        "status": "healthy",
        "timestamp": datetime.utcnow().isoformat()
    }

@app.get(
    "/v1/products",
    response_model=PaginatedResponse,
    summary="List products",
    tags=["Products"]
)
@limiter.limit("100/minute")
async def list_products(
    request: Request,
    pagination: PaginationParams = Depends(),
    filters: FilterParams = Depends()
):
    """
    List products with pagination and filtering.

    - **page**: Page number (default: 1)
    - **per_page**: Items per page (default: 20, max: 100)
    - **category**: Filter by category
    - **min_price**: Minimum price filter
    - **max_price**: Maximum price filter
    - **search**: Search in name and description
    - **sort**: Sort field (name, price, created_at)
    - **order**: Sort order (asc, desc)
    """
    # Implement service logic here
    products = await product_service.list_products(pagination, filters)

    # Generate HATEOAS links
    base_url = str(request.url).split('?')[0]
    links = generate_pagination_links(
        base_url,
        pagination.page,
        pagination.per_page,
        products['total_pages']
    )

    return PaginatedResponse(
        data=products['data'],
        pagination=products['pagination'],
        links=links
    )

@app.get(
    "/v1/products/{product_id}",
    response_model=Product,
    summary="Get product by ID",
    tags=["Products"]
)
async def get_product(product_id: str):
    """Get a single product by ID."""
    product = await product_service.get_product(product_id)
    if not product:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Product {product_id} not found"
        )
    return product

@app.post(
    "/v1/products",
    response_model=Product,
    status_code=status.HTTP_201_CREATED,
    summary="Create product",
    tags=["Products"]
)
@limiter.limit("10/minute")
async def create_product(
    request: Request,
    product: ProductCreate,
    user=Depends(get_current_user)
):
    """Create a new product (requires authentication)."""
    new_product = await product_service.create_product(product)

    # Set Location header
    response.headers["Location"] = f"{request.url}/{new_product.id}"

    return new_product

@app.put(
    "/v1/products/{product_id}",
    response_model=Product,
    summary="Update product",
    tags=["Products"]
)
async def update_product(
    product_id: str,
    product: ProductCreate,
    user=Depends(get_current_user)
):
    """Update an existing product (requires authentication)."""
    updated = await product_service.update_product(product_id, product)
    if not updated:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Product {product_id} not found"
        )
    return updated

@app.patch(
    "/v1/products/{product_id}",
    response_model=Product,
    summary="Partial update product",
    tags=["Products"]
)
async def patch_product(
    product_id: str,
    product: ProductUpdate,
    user=Depends(get_current_user)
):
    """Partially update a product (requires authentication)."""
    # Filter out None values
    update_data = product.dict(exclude_unset=True)

    if not update_data:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="No fields to update"
        )

    updated = await product_service.patch_product(product_id, update_data)
    if not updated:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Product {product_id} not found"
        )
    return updated

@app.delete(
    "/v1/products/{product_id}",
    status_code=status.HTTP_204_NO_CONTENT,
    summary="Delete product",
    tags=["Products"]
)
async def delete_product(
    product_id: str,
    user=Depends(get_current_user)
):
    """Delete a product (requires authentication)."""
    deleted = await product_service.delete_product(product_id)
    if not deleted:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Product {product_id} not found"
        )
    return None

# Error handlers
@app.exception_handler(ValueError)
async def value_error_handler(request: Request, exc: ValueError):
    return JSONResponse(
        status_code=400,
        content={
            "code": "VALIDATION_ERROR",
            "message": str(exc)
        }
    )

@app.exception_handler(HTTPException)
async def http_exception_handler(request: Request, exc: HTTPException):
    return JSONResponse(
        status_code=exc.status_code,
        content={
            "code": f"HTTP_{exc.status_code}",
            "message": exc.detail
        }
    )

if __name__ == "__main__":
    uvicorn.run(
        "main:app",
        host="0.0.0.0",
        port=8000,
        reload=True,
        log_level="info"
    )

Example 3: Integration Tests

// tests/products.test.js
const request = require('supertest');
const { app } = require('../src/app');
const { generateToken } = require('../src/utils/auth');

describe('Products API', () => {
    let authToken;
    let productId;

    beforeAll(async () => {
        // Generate auth token for protected routes
        authToken = await generateToken({ userId: 'test-user', role: 'admin' });
    });

    describe('GET /v1/products', () => {
        it('should return paginated products', async () => {
            const res = await request(app)
                .get('/v1/products')
                .query({ page: 1, perPage: 10 })
                .expect(200);

            expect(res.body).toHaveProperty('data');
            expect(res.body).toHaveProperty('pagination');
            expect(res.body).toHaveProperty('links');
            expect(res.body.data).toBeInstanceOf(Array);
            expect(res.body.data.length).toBeLessThanOrEqual(10);
        });

        it('should filter products by category', async () => {
            const res = await request(app)
                .get('/v1/products')
                .query({ category: 'electronics' })
                .expect(200);

            res.body.data.forEach(product => {
                expect(product.category).toBe('electronics');
            });
        });

        it('should handle invalid query parameters', async () => {
            const res = await request(app)
                .get('/v1/products')
                .query({ page: -1, perPage: 1000 })
                .expect(400);

            expect(res.body).toHaveProperty('code');
            expect(res.body).toHaveProperty('message');
        });
    });

    describe('POST /v1/products', () => {
        it('should create a new product', async () => {
            const newProduct = {
                name: 'Test Product',
                description: 'Test description',
                price: 99.99,
                inventory: 100,
                category: 'electronics'
            };

            const res = await request(app)
                .post('/v1/products')
                .set('Authorization', `Bearer ${authToken}`)
                .send(newProduct)
                .expect(201);

            expect(res.body).toHaveProperty('id');
            expect(res.body.name).toBe(newProduct.name);
            expect(res.headers).toHaveProperty('location');

            productId = res.body.id;
        });

        it('should validate required fields', async () => {
            const res = await request(app)
                .post('/v1/products')
                .set('Authorization', `Bearer ${authToken}`)
                .send({ name: 'Incomplete' })
                .expect(422);

            expect(res.body.code).toBe('VALIDATION_ERROR');
        });

        it('should require authentication', async () => {
            await request(app)
                .post('/v1/products')
                .send({ name: 'Test' })
                .expect(401);
        });
    });

    describe('GET /v1/products/:id', () => {
        it('should return a single product', async () => {
            const res = await request(app)
                .get(`/v1/products/${productId}`)
                .expect(200);

            expect(res.body.id).toBe(productId);
            expect(res.body).toHaveProperty('_links');
        });

        it('should return 404 for non-existent product', async () => {
            await request(app)
                .get('/v1/products/non-existent')
                .expect(404);
        });
    });

    describe('PATCH /v1/products/:id', () => {
        it('should partially update a product', async () => {
            const updates = { price: 89.99 };

            const res = await request(app)
                .patch(`/v1/products/${productId}`)
                .set('Authorization', `Bearer ${authToken}`)
                .send(updates)
                .expect(200);

            expect(res.body.price).toBe(89.99);
        });
    });

    describe('DELETE /v1/products/:id', () => {
        it('should delete a product', async () => {
            await request(app)
                .delete(`/v1/products/${productId}`)
                .set('Authorization', `Bearer ${authToken}`)
                .expect(204);

            // Verify deletion
            await request(app)
                .get(`/v1/products/${productId}`)
                .expect(404);
        });
    });
});

Error Handling

Error	Cause	Solution
"Invalid request body"	Malformed JSON or missing fields	Validate against schema
"Unauthorized"	Missing or invalid auth token	Include valid Bearer token
"Rate limit exceeded"	Too many requests	Implement backoff strategy
"Resource not found"	Invalid ID or deleted resource	Verify resource exists
"Validation error"	Data doesn't match schema	Check field requirements

Configuration Options

Framework Options

• Express.js: Node.js, middleware ecosystem
• FastAPI: Python, automatic OpenAPI docs
• NestJS: TypeScript, enterprise patterns
• Django REST: Python, batteries included
• Spring Boot: Java, enterprise features

Database Options

• PostgreSQL: Relational, ACID compliance
• MongoDB: Document store, flexible schema
• MySQL: Relational, wide support
• DynamoDB: Serverless, auto-scaling

Best Practices

DO:

• Use proper HTTP status codes consistently
• Implement comprehensive input validation
• Version your APIs from the start
• Include pagination for list endpoints
• Return consistent error formats
• Add request/response logging

DON'T:

• Mix authentication schemes
• Return sensitive data in errors
• Use GET for state-changing operations
• Ignore rate limiting
• Skip input validation
• Forget CORS configuration

Performance Considerations

• Implement database query optimization with indexes
• Use connection pooling for database connections
• Add caching layers (Redis, Memcached)
• Compress responses with gzip
• Implement pagination to limit response size
• Use CDN for static assets

Security Considerations

• Always use HTTPS in production
• Implement proper authentication (JWT, OAuth2)
• Validate and sanitize all inputs
• Use parameterized queries to prevent SQL injection
• Implement rate limiting per user/IP
• Add API key rotation mechanisms
• Log security events for audit

Related Commands

• /api-documentation-generator - Generate API docs
• /api-gateway-builder - Create API gateway
• /graphql-server-builder - Build GraphQL APIs
• /grpc-service-generator - Create gRPC services
• /webhook-handler-creator - Handle webhooks

Version History

• v1.0.0 (2024-10): Initial implementation with Express, FastAPI, NestJS support
• Planned v1.1.0: Add Spring Boot and Django REST Framework templates