Design Patterns MCP Server

{ "id": "domain-model", "name": "Domain Model", "category": "Enterprise", "description": "Object model of the domain that incorporates both behavior and data", "when_to_use": "Complex business logic\nRich domain models\nObject-oriented design", "benefits": "Rich behavior\nEncapsulation\nMaintainability\nTestability", "drawbacks": "Complex setup\nLearning curve\nOver-engineering risk", "use_cases": "Complex business rules\nFinancial systems\nEnterprise applications", "complexity": "High", "tags": [ "enterprise", "domain-logic", "object-oriented" ], "examples": { "typescript": { "language": "typescript", "code": "// Domain Model: rich behavior in domain objects\nclass Order {\n private items: OrderItem[] = [];\n private status: OrderStatus = 'pending';\n \n constructor(public readonly id: string, public customerId: string) {}\n \n addItem(product: Product, quantity: number): void {\n if (this.status !== 'pending') {\n throw new Error('Cannot modify confirmed order');\n }\n \n const existing = this.items.find(i => i.productId === product.id);\n if (existing) {\n existing.quantity += quantity;\n } else {\n this.items.push(new OrderItem(product.id, quantity, product.price));\n }\n }\n \n removeItem(productId: string): void {\n if (this.status !== 'pending') {\n throw new Error('Cannot modify confirmed order');\n }\n this.items = this.items.filter(i => i.productId !== productId);\n }\n \n calculateTotal(): number {\n return this.items.reduce((sum, item) => sum + item.getTotal(), 0);\n }\n \n confirm(): void {\n if (this.items.length === 0) {\n throw new Error('Cannot confirm empty order');\n }\n this.status = 'confirmed';\n }\n \n ship(): void {\n if (this.status !== 'confirmed') {\n throw new Error('Order must be confirmed before shipping');\n }\n this.status = 'shipped';\n }\n}\n\nclass OrderItem {\n constructor(\n public productId: string,\n public quantity: number,\n private unitPrice: number\n ) {}\n \n getTotal(): number {\n return this.quantity * this.unitPrice;\n }\n}\n\n// Usage: Rich domain behavior\nconst order = new Order('123', 'customer-1');\norder.addItem(new Product('prod-1', 'Item', 10), 2);\nconsole.log('Total:', order.calculateTotal()); // 20\norder.confirm();\norder.ship();" } } }