How to have fastcrud routes with some parameters in path arguments?

[nimitbhardwaj]

Suppose I have CRUD paths such as below

GET /api/schools/<school_id>/classes
POST /api/schools/<school_id>/classes
GET /api/schools/<school_id>/classes/<id>
DELETE /api/schools/<school_id>/classes/<id>
PATCH /api/schools/<school_id>/classes

where I want to create the CRUD methods for classes in context of school. For the create data call, I would want data similar to like below.

{
    "name": "<name>"
}

but in the DB, we would also be storing the name and school ID for the class table, class has a foreign key to school. So for these type of cases, how can I use fastCrud or crud_router.

[igorbenav]

You can handle nested resource CRUD in FastCRUD using the crud_router with path parameters and operation-specific dependencies. Here's how:

Option 1: Use path parameters in endpoint definitions

from fastcrud import crud_router

# Your models
class School(SQLModel, table=True):
    id: int | None = Field(primary_key=True)
    name: str

class Class(SQLModel, table=True):
    id: int | None = Field(primary_key=True)
    name: str
    school_id: int = Field(foreign_key="school.id")

# Create the router with path parameter
class_router = crud_router(
    session=get_session,
    model=Class,
    create_schema=ClassCreate,
    update_schema=ClassUpdate,
    path="/api/schools/{school_id}/classes",
    tags=["classes"]
)

Option 2: Use operation-specific dependencies to inject school_id

from fastapi import Path, Depends

def get_school_context(school_id: int = Path(...)):
    return {"school_id": school_id}

class_router = crud_router(
    session=get_session,
    model=Class,
    create_schema=ClassCreate,
    update_schema=ClassUpdate,
    path="/api/schools/{school_id}/classes",
    create_deps=[get_school_context],
    update_deps=[get_school_context]
)

Option 3: Custom create endpoint with automatic school_id injection

from fastapi import Body, Path, Depends
from sqlalchemy.ext.asyncio import AsyncSession

@class_router.post("")
async def create_class(
    school_id: int = Path(...),
    class_data: ClassCreate = Body(...),
    db: AsyncSession = Depends(get_session)
):
    # Automatically add school_id to the data
    create_data = class_data.model_dump()
    create_data["school_id"] = school_id
    
    return await fastcrud.create(db, Class, create_data)

The crud_router automatically handles the path parameters and you can inject the school_id into your operations through operation-specific dependencies (like create_deps, update_deps) or custom endpoint overrides.