How to set paginate params via query?

Question

One of my endpoints is supposed to be pageable. It's essentially just a wrapper around an external API, thus there's some workarounds unfortunately.

However, I'd like to know how I can set the params: Params via query parameters.

I expected there to be arguments page and size to be available as in /search?page=2&size=10 declaring them.

Since I wasn't able to find a single example I thought I might ask.

@search_router.get("/search")
def search(query: str, params: Params = Params(size=20), response_model=Page[dict]):

    result = ris_client.service.SearchDocuments({
           "DokumenteProSeite": PAGE_SIZE[params.size],
           "Seitennummer": params.page
    })

    results = result["results"]
    hits = results["hits"]
    content = results["references"]

    return paginate(
        content,
        params,
        length_function=lambda _: int(hits["value"])
    )

I know I could expose these parameters myself like so:

@search_router.get("/search")
def search(query: str, size: int = 20, page: int = 0, response_model=Page[dict]):
   params = Params(size=size, page=page)
   # ...
   return paginate(
        content,
        params,
        length_function=lambda _: int(hits["value"])
    )

but why is it then that I see the Params class in the function signature in almost every tutorial?

Answer 1

This Params from fastapi-pagination is just a small helper class, that does some prevalidation for you:

class Params(BaseModel, AbstractParams):
    page: int = Query(1, ge=1, description="Page number")
    size: int = Query(50, ge=1, le=100, description="Page size")

    def to_raw_params(self) -> RawParams:
        return RawParams(
            limit=self.size,
            offset=self.size * (self.page - 1),
        )

You can use it instead of explicitly passing those parameters to your endpoint.