中间件在流式响应 flask 应用程序中捕获异常

Question

This is an simple application that inserts data into a mysql db. The data gets inserted correctly but i am not getting the reponse of my post request but the status is 200.request.form works but i want to send json as payload This is my below route and i believe something is wrong when i am checking if the keys exist in my json payload. i tried using request.json,request.get_json,request.get_json() but i am unable to get rid of this error although the status is 200 but application is not returning any message.

@app.route('/pythonlogin/register', methods=['GET', 'POST'])
def register():
    # Output message if something goes wrong..
    msg = ''
    # current_time = time.strftime('%Y-%m-%d %H:%M:%S')
    # Check if "username", "password" and "email" POST requests exist (user submitted form)
    if request.method == 'POST' and request.get_json().get('name') != None and  request.get_json().get('password')  != None and  request.get_json().get('email')  != None and  request.get_json().get('size')!= None  :
        data = request.get_json().get
        # Create variables for easy access
        name = data('name')
        password = data('password')
        email = data('email')
        size = data('size')
        # Check if account exists using MySQL
        cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
        cursor.execute('SELECT * FROM user WHERE email = %s', (email,))
        account = cursor.fetchone()
        print(account)
        # If account exists show error and validation checks
        if account:
            msg = 'Account already exists!'
        elif not re.match(r'[^@]+@[^@]+\.[^@]+', email):
            msg = 'Invalid email address!'
        elif not re.match(r'[A-Za-z0-9]+', name):
            msg = 'Username must contain only characters and numbers!'
        elif not re.match(r'[0-9]',size):
            msg = 'Team size accepts only numbers'
        elif not name or not password or not email or not size:
            msg = 'Please fill out the form!'
        else:
            print('inside else')
            role = 1
            # Account doesnt exists and the form data is valid, now insert new account into accounts table
            cursor.execute('INSERT INTO company VALUES (NULL, %s,NULL, %s, %s)', (name, size,current_time))
            #cursor.execute('INSERT INTO user VALUES (NULL, %s, %s, NULL,NULL, NULL,NULL, NULL,NULL, NULL)', (email, password,))
            mysql.connection.commit()
            cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
            cursor.execute('SELECT * FROM company WHERE name = %s ' ,(name,))
            results = cursor.fetchone()
            comp_id = results['company_id']
            cursor.execute('INSERT INTO user VALUES (NULL, NULL, %s,%s, %s,NULL, NULL,NULL, %s,%s)', (email, password,role,current_time,comp_id,))
            mysql.connection.commit()
            msg = 'You have successfully registered!'
    else :
        # Form is empty... (no POST data)
        msg = 'Please fill out the form!'
    return {"status":"1","message":msg}

this is my below response:

Debugging middleware caught exception in streamed response at a point where response headers were already sent 

and this

MySQLdb._exceptions.OperationalError: (2006, '').

Answer 1

Eventually i declared this twice

mysql = MySQL(app)

Answer 2

Incase if you are using Flask-migrate, unapplied migrations also cause the same kind of exceptions. make sure you follow the below steps properly

flask db migrate

then if you skip the below step (un-apply the model changes to db). this will cause the same kind of exceptions. run the flask db upgrade command soon after using the flask db migrate command

flask db upgrade

then start the flask server and start hitting your apis.