whenever i try to import models.py in my main.py file it shows me sqlalchemy.exc.ArgumentError

Question

from xmlrpc.client import Boolean
from sqlalchemy import TIMESTAMP, Column, Integer, String
from sqlalchemy.sql.expression import text
from .database import Base

class Post(Base):
    __tablename__ = 'posts'

    id = Column(Integer, primary_key=True, nullable=False)
    title = Column(String, unique=True, nullable=False)
    content = Column(String, nullable=False)
    published = Column(Boolean, server_default='True', nullable=False)
    created_at= Column(TIMESTAMP(timezone=True), nullable= False, server_default=text)

I couldn't find the error. When I try to create the tables using models.Base.metadata.create_all(bind=engine) it gives me the following error:

Traceback (most recent call last):
  File "C:\Users\MINTU\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\sql\schema.py", line 125, in _init_items
    spwd = item._set_parent_with_dispatch
AttributeError: type object 'bool' has no attribute '_set_parent_with_dispatch'

The above exception was the direct cause of the following exception:

File "C:\Users\MINTU\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\util\compat.py", line 207, in raise_
    raise exception
sqlalchemy.exc.ArgumentError: 'SchemaItem' object, such as a 'Column' or a 'Constraint' expected, got <class 'bool'>

Answer 1

First, Boolean must not be imported from xmlrpc.client but from sqlalchemy

Second, the name of your table is not written as tablename but as __tablename__.

Third, text in TIMESTAMP must be called with an argument that I would let you adapt to your needs

from sqlalchemy import TIMESTAMP, Column, Integer, String, Boolean
from sqlalchemy.sql.expression import text
from .database import Base


class Post(Base): 
    __tablename__ = 'posts'

    id = Column(Integer, primary_key=True, nullable=False)
    title = Column(String, unique=True, nullable=False)
    content = Column(String, nullable=False)
    published = Column(Boolean, server_default='True', nullable=False)
    created_at= Column(TIMESTAMP(timezone=True), nullable= False, server_default=text('(now() at time zone "utc")'))