Flask AttributeError: 'NoneType' object 没有属性 'name'

Question

Working on a simple web app that should return "Hello, (name pulled from database)." It's saying that the object has no attribute for 'name' even though name is listed as an attribute in the class. Can't figure out why it thinks it's not there (unless I'm misunderstanding the error)?

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app=Flask(__name__)

app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://postgres@localhost:5432/example'
db = SQLAlchemy(app)

# initalizes the class/table
class Person(db.Model):
    __tablename__ = 'persons'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(), nullable=False)

db.create_all()

@app.route('/')
def index():
    person = Person.query.first()
    return 'Hello ' + person.name

Error:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/ZEMEL/Dropbox (Personal)/Code/hello/flask-hello-app.py", line 20, in index
    return 'Hello ' + person.name
AttributeError: 'NoneType' object has no attribute 'name'

Answer 1

your db either has no content in it or you are fetching the data the wrong way.

person=Person.query(name="name").first() 

should fetch the data with the first person with the name being "name"