Tell Claude to Follow an Existing File's Pattern When Creating New Ones

Every codebase has patterns — how controllers are structured, how services handle errors, how components organize their props. When you need a new file that fits in, point Claude at an existing one as the template.

"Create a ProductController following the exact same pattern as UserController"

Claude reads the referenced file, extracts the conventions — response format, error handling approach, validation style, method organization — and applies them to the new file. The result looks like it was written by the same developer on the same day.

This works for any kind of file:

# Components
"Create a ProductCard component following the pattern in UserCard.tsx"

# Services
"Write an OrderService following the same structure as PaymentService"

# Tests
"Write tests for the OrderController following the same style as UserControllerTest"

# Migrations
"Create a migration for the products table following the pattern of the orders migration"

# API Resources
"Create a ProductResource following the same structure as UserResource"

You can reference multiple files for more context:

"Create the full CRUD for products — controller, model, migration, tests, and routes —
following the same patterns used for the users module"

Claude reads all the user-related files and creates matching product files — same validation patterns, same response shapes, same test structure, same route grouping.

This is especially useful when:

• Onboarding — new team members create consistent code from day one
• Expanding features — adding a new resource type that should match existing ones
• Maintaining consistency — keeping the codebase uniform even as it grows
• Following team conventions — conventions that aren't documented but are visible in existing code

The best code standards aren't in a style guide — they're in the code itself. Point Claude at the example and it follows the pattern.

via Claude Code