fastapi-routes

FastAPI Routes

context7: If the context7_query-docs tool is available, resolve and load the full fastapi documentation before proceeding:

context7_resolve-library-id: "fastapi"
context7_query-docs: /fastapi/fastapi "<your query>"

Guidelines and patterns for writing FastAPI routes in this codebase.

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REST Principles

APIs must adhere as closely as possible to REST principles, including appropriate use of HTTP verbs:

Verb	Usage
GET	Read one or many resources
POST	Create a new resource
PUT	Replace / fully update a resource
PATCH	Partial update (use sparingly)
DELETE	Remove a resource

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Pydantic Models

• Always use Pydantic models for both input and output — never use plain dict or Any.
• Never reuse the same model for input and output. Use separate models:
  • PostCreate — user input for creating a resource
  • PostUpdate — user input for updating (optional fields)
  • PostRead — response shape returned to the client
• Parameters in input models must use Field() with validation constraints and a description.
• Output models do not require Field() unless you need aliases or serialization control.

from uuid import UUID
from pydantic import BaseModel, Field


class PostCreate(BaseModel):
    title: str = Field(min_length=1, max_length=200, description="Post title")
    content: str = Field(min_length=1, description="Post content")


class PostRead(BaseModel):
    id: UUID
    title: str
    content: str
    created_at: str


class PostUpdate(BaseModel):
    title: str | None = Field(default=None, max_length=200, description="Post title")
    content: str | None = Field(default=None, description="Post content")

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Router Pattern

Use APIRouter for all routes. Register the router in {{cookiecutter.__package_slug}}/www.py.