It is the first time I ask here as I am new. But I have spent two days with chatgpt and coudnt solve the problem.

When I want to do a POST I receive the following issue message.
{
“error”: “‘dict’ object has no attribute ‘_sa_instance_state'”
}

I want to create table named “event”, another one named “music_type” and create a relationship between them. However, every time I run my POST (create event function) I receive the error message.

# **MODELS/Events**

from typing import List
from config.database import Base
from sqlalchemy import Column, Integer, String, Float, Enum, Date, Table, ForeignKey
from sqlalchemy.orm import relationship, Mapped, mapped_column, DeclarativeBase
from enum import Enum as PydanticEnum
from models.music_type import MusicType

class PriceType(PydanticEnum):
    FREE = "FREE"
    ADMISSION = "ADMISSION"
    CONSUMPTION = "CONSUMPTION"

# Tabla de relación many-to-many entre Event y MusicType
event_music_types = Table(
    "event_music_types",
    Base.metadata,
    Column("event_id", Integer, ForeignKey("events.id")),
    Column("music_type_id", Integer, ForeignKey("music_types.id"))
)

class Event (Base):

    __tablename__ = "events"

    id = Column (Integer, primary_key = True)
    title = Column (String)
    description = Column (String)
    date = Column (Date)
    place = Column (String)
    street = Column (String)
    city = Column (String)
    organizer = Column (String)
    price_type = Column (Enum(PriceType))
    price_amount = Column (Float)
    music_types = relationship("MusicType", secondary="event_music_types", backref="events", lazy="joined")

# **MODELS/Music_Type**

from config.database import Base
from sqlalchemy import Column, Integer, String

class MusicType(Base):
    __tablename__ = "music_types"

    id = Column(Integer, primary_key=True)
    name = Column(String, unique=True)



##**MY FUNCTION CODE SERVICES/event.py**

from models.event import Event as EventModel
from models.music_type import MusicType as MusicTypeModel
from schemas.event import Event
from schemas.music_type import MusicType
from sqlalchemy import or_
from typing import List


class EventService():

    def __init__(self, db) -> None:
        self.db = db

    def get_events(self):
        result = self.db.query(EventModel).all()
        return result
    
    
    def create_event(self, event: Event):
        new_event = EventModel(**event.model_dump())
        music_types = []
        # Iterar sobre los tipos de música proporcionados en la solicitud JSON
        for music_type_data in event.music_types:
            music_type = self.db.query(MusicTypeModel).filter(MusicTypeModel.name == music_type_data.name).first()
            if music_type:
                music_types.append(music_type)
            else:
            # Si el tipo de música no existe, manejar el caso aquí
                new_music_type = MusicTypeModel(name=music_type_data.name)
                self.db.add(new_music_type)
                self.db.commit()
                music_types.append(new_music_type)
            
        # Agregar el evento a la base de datos y realizar la confirmación
        new_event.music_types.extend(music_types)
        self.db.add(new_event)
        self.db.commit()
        self.db.refresh(new_event)
        return


# **MY ROUTER CODE**
# 
    @event_router.post('/events', tags=['events'], response_model=dict, status_code=201)
    def create_event( event: Event ) -> dict:
    db = Session()
    # Agrega el print aquí para verificar los datos de event.music_types
    print(event.music_types)

    EventService(db).create_event(event)
    return JSONResponse(status_code=201, content={"message": "Se ha registrado el evento"})