日期类型的对象不是 JSON 可序列化的 - Python/SendGrid

Question

我使用了一个应用程序，但在将日期字段发送到 SendGrid 时遇到了问题。 我不断收到错误“日期类型的对象不是 JSON 可序列化的”。 我曾尝试查找其他帖子，但无法弄清楚问题出在哪里。

以下是我到目前为止所做的，在此先感谢您的帮助。

要获得日期，我首先需要过滤 BookingInfo 表，我已按如下方式完成。

two_days_before = date.today() + timedelta(days=2)
sess = Session()

nutri_sess_date = sess.query(BookingInfo.booking_date).filter(
                                                                BookingInfo.booking_link == "",
                                                                BookingInfo.booking_date == two_days_before,
                                                                BookingInfo.type_id == 1
                                                            ).all()

预订日期字段的输出是 [(datetime.date(2021, 11, 19),)]。

我已尝试使用以下代码将数据转换为 json，该代码已在其他应用程序中工作，但在将转换后的字段添加到 SendGrid 时仍然出现错误。

 # Format and Serialise Date and Time
    formatted_date = {'date': nutri_sess_date}
    json_date = formatted_date['date']

    ## Add message data
    message.dynamic_template_data = {
            'username'      : nutri_contact_name,
            'sessname'    : 'Nutrition Advancement',
            'sessionmail'   : 'nutrition.advancement@vis.org.au',
            'sessdate' : json_date,
            'sesstime' : nutri_sess_time,

        }

下面是代码。

import time
from datetime import datetime, timedelta, date
import datetime
import pymysql, mysql
from sqlalchemy.orm import scoped_session, sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine, MetaData, inspect, Column, Integer, TEXT, DATETIME, DATE
from sendgrid import SendGridAPIClient
from sendgrid.helpers.mail import Mail, To

SENDGRID_API_KEY = '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'

# Database Connections:

class DBConnect:

    def __init__(self):
        self.oserver = '@vicinstofsport.mysql.pythonanywhere-services.com/'
        self.oname = 'vicinstofsport$pep-booking'
        self.ouser = 'vicinstofsport'
        self.opw = '28aQhbQ7@7DYrh7a'

    def online(self):
        engine = create_engine('mysql+pymysql://'+self.ouser+':'+self.opw+self.oserver+self.oname, pool_recycle=280, isolation_level="READ UNCOMMITTED")
        db = DBConnect.connections(engine)
        return db

    @staticmethod
    def connections(engine):
        con = scoped_session(sessionmaker(autocommit=True,autoflush=False,bind=engine))
        Session = sessionmaker(bind=engine)
        meta = MetaData(engine)
        insp = inspect(engine)
        Base = declarative_base()
        db = {
            'engine':engine,
            'con':con,
            'sess':Session,
            'meta':meta,
            'insp':insp,
            'Base':Base
        }
        con.close()
        engine.dispose()
        return db

# Database Connections:
db = DBConnect()
db = db.online()
Session = db['sess']
Base = db['Base']

class BookingInfo(Base):

    __tablename__ = 'booking_info'

    _id = Column(Integer, primary_key=True)
    booking_id = Column(Integer)
    type_id = Column(Integer)
    booking_date = Column(DATE)
    booking_time = Column(TEXT)
    booking_length = Column(Integer)
    sch_name = Column(TEXT)
    sch_street = Column(TEXT)
    sch_sub = Column(TEXT)
    sch_state = Column(TEXT)
    sch_postal = Column(TEXT)
    sch_location = Column(TEXT)
    sch_type = Column(TEXT)
    sess_type = Column(TEXT)
    no_students = Column(Integer)
    no_male = Column(Integer)
    no_female = Column(Integer)
    sch_year = Column(TEXT)
    contact_name = Column(TEXT)
    contact_email = Column(TEXT)
    contact_phone = Column(TEXT)
    virtual_platform = Column(TEXT)
    notes = Column(TEXT)
    teacher_present = Column(Integer)
    presenter = Column(TEXT)
    survey_sent = Column(Integer)
    booking_link = Column(TEXT)

def nutri_survey(email_address):
    template_id = 'd-1680872ea61b4c878692d836789c6f3d'
    message = Mail(
                    from_email = 'noreply@vis.org.au',
                    to_emails = email_address,
                    is_multiple=True
                )

    ### Get SendGrid Message Data.
    two_days_before = date.today() + timedelta(days=2)
    sess = Session()

    nutri_contact_name = sess.query(BookingInfo.contact_name).filter(
                                                                    BookingInfo.booking_link == "",
                                                                    BookingInfo.booking_date == two_days_before,
                                                                    BookingInfo.type_id == 1
                                                                ).all()

    nutri_sess_date = sess.query(BookingInfo.booking_date).filter(
                                                                    BookingInfo.booking_link == "",
                                                                    BookingInfo.booking_date == two_days_before,
                                                                    BookingInfo.type_id == 1
                                                                ).all()


    nutri_sess_time = sess.query(BookingInfo.booking_time).filter(
                                                                    BookingInfo.booking_link == "",
                                                                    BookingInfo.booking_date == two_days_before,
                                                                    BookingInfo.type_id == 1
                                                                ).all()
    sess.commit()
    sess.close()

    print(nutri_sess_date)

    # Format and Serialise Date and Time
    formatted_date = {'date': nutri_sess_date}
    json_date = formatted_date['date']

    ## Add message data
    message.dynamic_template_data = {
            'username'      : nutri_contact_name,
            'sessname'    : 'Nutrition Advancement',
            'sessionmail'   : 'nutrition.advancement@vis.org.au',
            'sessdate' : json_date,
            'sesstime' : nutri_sess_time,

        }
    message.template_id = template_id
    try:
        sg = SendGridAPIClient(SENDGRID_API_KEY)
        response = sg.send(message)
    except Exception as e:
        print(e)