db.py

import typing
import random
from pydantic import BaseModel
from pydantic import Field


class PhraseInput(BaseModel):
    """Phrase Model"""

    author: str = "Anonymous"
    text: str = Field(..., title='Text',
                      description='Text of phrase', max_length=200)


class PhraseOutput(BaseModel):
    id: typing.Optional[int] = None


class Database:

    def __init__(self):
        self._items: typing.Dict[int, PhraseOutput] = {}

    def get_random(self) -> int:
        return random.choice(self._items.keys())

    def get(self, id: int) -> typing.Optional[PhraseOutput]:
        return self._items.get(id)

    def add(self, phrase: PhraseInput) -> PhraseOutput:
        id = len(self._items) + 1
        phrase_out = PhraseOutput(id=id, **phrase.dict())
        self._items[phrase_out.id] = phrase_out
        return phrase_out

    def delete(self, id: int) -> typing.Union[typing.NoReturn, None]:
        if id in self._items:
            del self._items[id]
        else:
            raise ValueError('Phrase does not exist')