name: prisma-development
description: Comprehensive Prisma ORM development guidelines with TypeScript, schema design, migrations, and best practices.

Prisma ORM Development

You are an expert in Prisma ORM development with TypeScript.

TypeScript Fundamentals

Basic Principles

• Always declare explicit types for variables and functions
• Avoid using 'any'
• Leverage JSDoc for public APIs
• Maintain single exports per file
• Prioritize self-documenting code

Naming Conventions

• PascalCase for classes/interfaces
• camelCase for variables and methods
• kebab-case for files/directories
• UPPERCASE for constants
• Verb-based boolean names (isLoading, hasError, canDelete)

Function Design

• Aim for less than 20 lines of code per function
• Single responsibility per function
• Implement early returns
• Extract complex logic into separate functions
• Leverage functional patterns (map, filter, reduce)
• Use object parameters for multiple arguments

Data & Error Handling

• Encapsulate data in composite types with immutability preference
• Use readonly and as const appropriately
• Validate at boundaries
• Employ specific, descriptive error types with contextual messaging

Prisma-Specific Practices

Schema Design

• Domain-driven naming for models and fields
• Explicit relations using @relation
• Normalized structures where appropriate
• Soft deletes via deletedAt field
• Native type decorators for database-specific types

Client Usage

• Always use type-safe Prisma client operations
• Use transactions for complex flows
• Implement middleware for logging, soft deletes, and auditing
• Use select and include judiciously to avoid over-fetching

Migrations

• Create descriptive migrations with clear naming
• Never modify existing migrations
• Ensure idempotency for all migrations
• Test migrations on staging before production

Error Handling

• Catch PrismaClientKnownRequestError for constraint violations
• Handle PrismaClientUnknownRequestError for unexpected database errors
• Validate with PrismaClientValidationError for schema mismatches

Quality Standards

• Avoid N+1 queries through proper eager loading
• Test with in-memory databases for speed
• Mock Prisma client for unit test isolation
• Never expose raw Prisma clients in APIs
• Validate all user inputs before database operations
• Follow SOLID principles with composition over inheritance