paged query model

pagination.py

import typing
from cryptography.fernet import Fernet
from pydantic import BaseModel

from lib.conf import config


fernet = Fernet(config.FEED_FERNET_KEY)


class BasePageQuery(BaseModel):
    """
    This class generate **next_page** parameter for pagination. Encrypted
    string contains all attributes described in child class.

    Example:
        >>> class MyPageQuery(BasePageQuery):
        >>>     filter_by: str = 'date'
        >>>     order: str = 'asc'
        >>>
        >>> query = MyPageQuery(filter_by='users', order='desc')
        >>>
        >>> encrypted_next_page = query.as_str
        >>> assert MyPageQuery.from_str(encrypted_next_page) == query
        >>>
        >>> encrypted_next_page = str(query)
        >>> assert MyPageQuery.from_str(encrypted_next_page) == query
    """

    @classmethod
    def from_str(cls, text: str) -> "BasePageQuery":
        """
        Decrypt dictionary and return BasePageQuery from encrypted
        json string

        @param text: encrypted with Fernet text
        @return: assembled NextPageObject
        """
        data = fernet.decrypt(text.encode())
        return cls.parse_raw(data)

    @property
    def as_str(self) -> str:
        """
        Dump BasePageQuery into encrypted with Fernet json representation

        @return: encrypted text
        """
        data = fernet.encrypt(self.json(exclude_unset=True).encode())
        return data.decode()

    def __str__(self) -> str:
        return self.as_str


class NextPageQueryStressTrend(BasePageQuery):
    last_id: typing.Any = None