CURSOR RULESPython FastAPI Cursor Rules (.mdc) | Free & Offline
Production-grade architectural rulebook for Python FastAPI & Pydantic v2. Engineered to eliminate LLM hallucinations, enforce strict deterministic conventions, and prevent architectural drift across Cursor IDE, Claude Code CLI, and autonomous multi-agent pipelines.
.cursor/rules/fastapi.mdcFailure Patterns Prevented for Python FastAPI & Pydantic v2
FastAPI with Pydantic v2 requires `model_validator` instead of `@root_validator`, Field annotations, and strict async I/O. Without rules, AI models blend outdated Pydantic v1 syntax and synchronous database calls inside async handlers.
- Invokes deprecated or removed APIs from older model training weights
- Generates conflicting configuration files and invalid imports
- Silently drops type-safety, boundaries, or transaction isolation
Code Standards: Anti-Pattern vs Verified Implementation
@app.post("/users")
def make_user(data: dict):
# Missing types, sync blocking query
return db.query(data["email"])from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel, Field
router = APIRouter()
class UserPayload(BaseModel):
email: str = Field(..., min_length=5)
@router.post("/users")
async def create_user(payload: UserPayload, db = Depends(get_db)):
return await db.users.create(payload.model_dump())How to Install Python FastAPI & Pydantic v2 Cursor Rules (.mdc) via Terminal
Step 1: Open Project Directory & Verify Target Placement
Open your terminal and navigate to your project root folder where the .cursor/rules/fastapi.mdc file will reside. Ensure the file is placed at the exact path below relative to your project root so the AI engine automatically loads it:
Step 2: Fetch Rule File via Terminal Command
Run curl, PowerShell, or wget to stream the rule directly from the DevScratchpad raw API endpoint and write it to .cursor/rules/fastapi.mdc:
Terminal One-Liner Install
Run directly in your project root to stream and write this rule file with one command.
mkdir -p ".cursor/rules" && curl -fsSL "https://www.devscratchpad.tech/api/raw/cursor-rules/fastapi" -o ".cursor/rules/fastapi.mdc"Step 3: Verify and Activate with AI Agent
Launch your AI coding assistant (Cursor IDE & Composer). The assistant will automatically discover .cursor/rules/fastapi.mdc in your repository and apply the architectural guardrails, type constraints, and verification protocols during code generation.
Cursor Rules (.mdc) Directory & Generator
Inspect the complete specification manual, glob patterns, directory rules, and all available presets in our central directory.
Technical FAQ: Python FastAPI & Pydantic v2 AI Rulebooks
Does this enforce Pydantic v2 syntax?
Yes, it specifically enforces `model_dump()`, `@field_validator`, and Pydantic v2 idioms.