Design Patterns MCP Server

{ "id": "dao-pattern", "name": "Data Access Object (DAO)", "category": "Data Access", "description": "Abstract interface to database or persistence mechanism", "when_to_use": "Database abstraction\nLegacy systems\nMultiple data sources", "benefits": "Database independence\nCentralized data access\nCode reusability", "drawbacks": "Additional layer\nComplexity\nPerformance overhead", "use_cases": "Enterprise applications\nLegacy database integration\nMulti-database systems", "complexity": "Medium", "tags": [ "data-access", "abstraction", "database" ], "examples": { "typescript": { "language": "typescript", "code": "// DAO: Data Access Object - abstract persistence layer\ninterface User {\n id: string;\n email: string;\n name: string;\n}\n\ninterface UserDAO {\n findById(id: string): Promise<User | null>;\n findAll(): Promise<User[]>;\n save(user: User): Promise<void>;\n delete(id: string): Promise<void>;\n}\n\nclass PostgresUserDAO implements UserDAO {\n constructor(private db: Database) {}\n \n async findById(id: string): Promise<User | null> {\n const row = await this.db.query('SELECT * FROM users WHERE id = $1', [id]);\n return row ? this.mapToUser(row) : null;\n }\n \n async findAll(): Promise<User[]> {\n const rows = await this.db.query('SELECT * FROM users');\n return rows.map(this.mapToUser);\n }\n \n async save(user: User): Promise<void> {\n await this.db.query(\n 'INSERT INTO users (id, email, name) VALUES ($1, $2, $3) ON CONFLICT (id) DO UPDATE SET email = $2, name = $3',\n [user.id, user.email, user.name]\n );\n }\n \n async delete(id: string): Promise<void> {\n await this.db.query('DELETE FROM users WHERE id = $1', [id]);\n }\n \n private mapToUser(row: any): User {\n return { id: row.id, email: row.email, name: row.name };\n }\n}\n\nconst userDAO: UserDAO = new PostgresUserDAO(db);\nconst user = await userDAO.findById('123');" } } }