How to declare a range in the datetime while creating a column in SQLalchemy?

I have a table named "Employee", where I have a requirement to set the column value of "hire date" to a datetime object in the format of 'YYYY-MM-DD HH:MM:SS', with a range from 01-01-2020 00:00:00 to today. I did the following:

class Employee(db.Model):
  id = db.Column(db.Integer, primary_key=True)
  name = db.Column(db.String(50))
  department = db.Column(db.String(50))
  salary = db.Column(db.Float, db.CheckConstraint('salary > 0 AND salary < 100'))
  hire_date =db.Column(DateTimeRange("2020-01-01 00:00:00", datetime.date.today())) 

  def __init__(self, name, department, salary, hire_date):
    self.name = name
    self.department = department
    self.salary = salary
    self.hire_date = hire_date

# Employee Schema
class EmployeeSchema(ma.Schema):
  class Meta:
    fields = ('id', 'name', 'department', 'salary', 'hire_date')

# Init schema
employee_schema = EmployeeSchema(strict = True)
employees_schema = EmployeeSchema(many=True)

So when I am trying to create the table in sqlite, I'm getting this error:

> in _init_items raise exc.ArgumentError( sqlalchemy.exc.ArgumentError:
> 'SchemaItem' object, such as a 'Column' or a 'Constraint' expected,
> got 2020-01-01T00:00:00 - 2023-05-07T00:00:00

Can anyone help me with this problem? How do I define the constraint?

Update:
I tried putting the current datetime in a variable to do something like this:

current_datetime = datetime.date.today()
  hire_date =db.Column(db.DateTime,  db.CheckConstraint('hire_date => "2020-01-01 00:00:00" AND hire_date <= current_datetime')) 

Which is giving me this error now:

> sqlite3.OperationalError: near ">": syntax error

For the time constraint on the hire_date, I'd suggest:

__table_args__ = (
  CheckConstraint("hire_date BETWEEN '2020-01-01 00:00:00' AND CURRENT_TIMESTAMP"),
    )

After your third update : you should use:

db.Column(
  db.DateTime, db.CheckConstraint(
    'hire_date >= "2020-01-01 00:00:00" AND hire_date <= current_timestamp'
  )
)

=> is an error; for the current time, maybe for sqlite you should use datetime('now', 'localtime').