JSON поле в peewee + pydantic (FastAPI)

from peewee import Model, CharField, DateField, BooleanField, ForeignKeyField, Field
from playhouse.postgres_ext import JSONField
 
 
class TeacherContest(BaseModel):
    teacher = ForeignKeyField(User, backref='users')
    contest = ForeignKeyField(Contest, backref='contests')
    nomination = CharField()
    union = CharField()
    collective = BooleanField()
    participants = JSONField()
    created = DateField(default=datetime.date.today())
 
    class Meta:
        db_table = 'teacher_contests'

import peewee
from pydantic import BaseModel, Json
from pydantic.utils import GetterDict
from pydantic.schema import date
 
 
class ContestTeacherCreate(ContestBaseSchema):
    nomination: str
    union: str
    collective: bool
    participants: Json

@app.post("/contest/create", response_model=ContestTeacherCreate, dependencies=[Depends(get_current_user)])
async def create_contest(create_contest_data: ContestTeacherCreate,
                         current_user: UserSchema = Depends(get_current_user)):
    teacher_contest = create_teacher_contest(current_user, create_contest_data)
    return teacher_contest

create_teacher_contest

def create_teacher_contest(user: UserSchema, teacher_contest: ContestTeacherCreate) -> ContestTeacher:
    contest_id = None
    try:
        contest = Contest.get_or_none(name=teacher_contest.name)
        if contest:
            pass
        else:
            contest = Contest.create(name=teacher_contest.name,
                                     level=teacher_contest.level,
                                     distant=teacher_contest.distant,
                                     place=teacher_contest.place,
                                     date=teacher_contest.date)
            contest.save()
        contest_id = contest.get_id()
    except IntegrityError:
        pass
    teacher_contest = TeacherContest.create(teacher=user.id,
                                            contest=contest_id,
                                            nomination=teacher_contest.nomination,
                                            union=teacher_contest.union,
                                            collective=teacher_contest.collective,
                                            participants=teacher_contest.participants)
    teacher_contest.save()
    contest_teacher = User.get_by_id(teacher_contest.teacher_id)
    result = ContestTeacher(teacher=' '.join([contest_teacher.surname, contest_teacher.name,
                                              contest_teacher.patronymic]),
                            contests=TeacherContest.filter(TeacherContest.teacher == teacher_contest.teacher_id))
    return result

"JSON object must be str, bytes or bytearray"

import json
 
json_string = json.dumps({"Key": "Value"})