Fastapi, Pydantic, Sqlalchemy List filter, order, limit model

filter.py

from typing import List, Optional

from accentdatabase.session import get_session
from fastapi import Depends, Query
from pydantic import BaseModel, Field
from sqlalchemy import func, or_, select
from sqlalchemy.ext.asyncio import AsyncSession

from models import Model


class ListFilter(BaseModel):
    """
    usage:
        ?search=foo
        ?search=foo&search=bar
        ?limit=100
        ?search=foo&limit=100
        
    ordering is by the searched fields in order for simplicity only   
    """

    limit: int = 200
    search: Optional[List[str]] = Field(Query([]))

    @property
    def search_regex(self):
        q = "".join(map(lambda s: f"(?=.*{s})", self.search))
        return f"{q}.*"

    def prepare(self, statement, *search_field):
        if len(self.search) > 0:
            terms = map(lambda f: f.op("~*")(self.search_regex), search_field)
            statement = statement.filter(or_(*terms))
        return statement.limit(self.limit).order_by(*search_field)
        


@router.get("", response_model=List[ModelRead])
async def get_items(
    filters: ListFilter = Depends(),
    session: AsyncSession = Depends(get_session),
):
    qs = filters.prepare(select(Model), Model.name, Model.title)
    return list(await session.scalars(qs))