Rest Api 帖子定义失败 | 蟒蛇| 烧瓶

Question

I am very new to python. I have basic idea with python and flask is totally new for me. Trying to learn rest api with python using flask. But, I am facing the issue while posting data. below are sample code and error. Please help me to fix this issue. Thanks in advance. I tried googling but did not get any solution.

Error while running

127.0.0.1 - - [03/Jan/2020 15:58:54] "POST /api/User HTTP/1.1" 500 -
  Traceback (most recent call last):
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1997, in __call__
      return self.wsgi_app(environ, start_response)
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1985, in wsgi_app
      response = self.handle_exception(e)
    File "/usr/local/lib/python3.7/site-packages/flask_restful/__init__.py", line 273, in error_router
      return original_handler(e)
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1540, in handle_exception
      reraise(exc_type, exc_value, tb)
    File "/usr/local/lib/python3.7/site-packages/flask/_compat.py", line 32, in reraise
      raise value.with_traceback(tb)
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1982, in wsgi_app
      response = self.full_dispatch_request()
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1614, in full_dispatch_request
      rv = self.handle_user_exception(e)
    File "/usr/local/lib/python3.7/site-packages/flask_restful/__init__.py", line 273, in error_router
      return original_handler(e)
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1517, in handle_user_exception
      reraise(exc_type, exc_value, tb)
    File "/usr/local/lib/python3.7/site-packages/flask/_compat.py", line 32, in reraise
      raise value.with_traceback(tb)
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1612, in full_dispatch_request
      rv = self.dispatch_request()
    File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1598, in dispatch_request
      return self.view_functions[rule.endpoint](**req.view_args)
    File "/usr/local/lib/python3.7/site-packages/flask_restful/__init__.py", line 480, in wrapper
      resp = resource(*args, **kwargs)
    File "/usr/local/lib/python3.7/site-packages/flask/views.py", line 84, in view
      return self.dispatch_request(*args, **kwargs)
    File "/usr/local/lib/python3.7/site-packages/flask_restful/__init__.py", line 595, in dispatch_request
      resp = meth(*args, **kwargs)
    File "/Users/z0034ff/Documents/music/resources/Users.py", line 32, in post
      typeid=json_data['typeid'],
  TypeError: __init__() got an unexpected keyword argument 'fname'

File name: Model.py

from flask import Flask
  from marshmallow import Schema, fields, pre_load, validate
  from flask_marshmallow import Marshmallow
  from flask_sqlalchemy import SQLAlchemy


  ma = Marshmallow()
  db = SQLAlchemy()


  class Users(db.Model):
      __tablename__ = 'users'
      id = db.Column(db.Integer, primary_key=True)
      fname = db.Column(db.String(50), nullable=False)
      lname = db.Column(db.String(50), nullable=False)
      email = db.Column(db.String(100), nullable=False)
      phone = db.Column(db.String(50), nullable=False)
      typeid = db.Column(db.Integer, db.ForeignKey(
          'user_type.id', ondelete='CASCADE'), nullable=False)
      creation_date = db.Column(
          db.TIMESTAMP, server_default=db.func.current_timestamp(), nullable=False)

      def __init__(self, users, typeid):
          self.users = users
          self.typeid = typeid

  class UsersSchema(ma.Schema):
      id = fields.Integer(dump_only=True)
      fname = fields.String(required=True, validate=validate.Length(1))
      lname = fields.String(required=True, validate=validate.Length(1))
      email = fields.String(required=True, validate=validate.Length(1))
      phone = fields.String(required=True, validate=validate.Length(10))
      typeid = fields.Integer(required=True)
      creation_date = fields.DateTime()

File name: Users.py

from flask import jsonify, request
  from flask_restful import Resource
  from Model import db, Users, UsersSchema

  users_schema = UsersSchema(many=True)
  user_schema = UsersSchema()


  class UsersResource(Resource):
      def get(self):
          users = Users.query.all()
          users = users_schema.dump(users).data
          return {"status": "success", "data": users}, 200

      def post(self):
          json_data = request.get_json(force=True)
          if not json_data:
              return {'message': 'No input data provided'}, 400
          # Validate and deserialize input
          data, errors = user_schema.load(json_data)
          if errors:
              return errors, 422
          user = Users.query.filter_by(email=data['email']).first()
          if user:
              return {'message': 'User already exists'}, 400
          print(json_data['fname'])
          user = Users(
              fname=json_data['fname'],
              lname=json_data['lname'],
              email=json_data['email'],
              phone=json_data['phone'],
              typeid=json_data['typeid'],
          )

          db.session.add(user)
          db.session.commit()

          result = user_schema.dump(user).data

          return {"status": 'success', 'data': result}, 201

Answer 1

It is not necessary to define SQLAlchemy model constructor. The SQLAlchemy docs explains:

Our User class, as defined using the Declarative system, has been provided with a constructor (eg init () method) which automatically accepts keyword names that match the columns we've mapped. We are free to define any explicit init () method we prefer on our class, which will override the default method provided by Declarative.

In Users.py line 27 you try to create Users object

          Users(
              fname=json_data['fname'],
              lname=json_data['lname'],
              email=json_data['email'],
              phone=json_data['phone'],
              typeid=json_data['typeid'],
          )

Where in Model.py constructor of Users class takes only 2 arguments.

  class Users(db.Model):
    ....

      def __init__(self, users, typeid):
          ...

That's where the error comes from: TypeError: __init__() got an unexpected keyword argument 'fname'

After removing __init__ it should work fine.