TypeError TypeError：connect() 参数 3 必须是 str，而不是 list

Question

I am new to python, sqlalchemy and flask. Right now i am trying to do a simple database insert program where artist_name is inserted into a database I have already created.

from flask import Flask, render_template, request, redirect
from flask_mysqldb import MySQL
import yaml
app = Flask(__name__)
db = yaml.load(open('db.yaml'))
app.config['MYSQL_HOST'] = db['mysql_host']
app.config['MYSQL_USER'] = db['mysql_user']
app.config['MYSQL_PASSWORD'] = ['mysql_password']
app.config['MYSQL_DB'] = ['mysql_db']
mysql = MySQL(app)
@app.route('/', methods=['GET', 'POST'])
def index():
    if request.method == 'POST':
        # Fetch form data
        userDetails = request.form
        artist_name = userDetails['artist_name']
        
        cur = mysql.connection.cursor()
        cur.execute("INSERT INTO p_artist ( artist_name) VALUES (%s)", (artist_name))
        mysql.connection.commit()
        cur.close()
        return 'inserted'
        
    return render_template('index.html')
if __name__ == '__main__':
    app.run(debug=True)

HTML
 <form method="POST" action="">
    <br>
      artist_name <input type="text" name="artist_name" />
    <br>
      <input type="submit">
   </form>

db.yaml

mysql_host: 'localhost'
mysql_user: 'root'
mysql_password: 
mysql_db:** 

this is the type error

TypeError
TypeError: connect() argument 3 must be str, not list
Traceback (most recent call last)
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 2450, in wsgi_app
                try:
                    ctx.push()
                    response = self.full_dispatch_request()
                except Exception as e:
                    error = e
                    response = self.handle_exception(e)
                except:  # noqa: B001
                    error = sys.exc_info()[1]
                    raise
                return response(environ, start_response)
            finally:
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\_compat.py", line 39, in reraise
    raise value
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\_compat.py", line 39, in reraise
    raise value
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask\app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
    File "C:\Users\luvch\OneDrive\Desktop\New folder\hope.py", line 25, in index
    cur = mysql.connection.cursor()
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask_mysqldb\__init__.py", line 94, in connection
    ctx.mysql_db = self.connect
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\flask_mysqldb\__init__.py", line 81, in connect
    return MySQLdb.connect(**kwargs)
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\MySQLdb\__init__.py", line 130, in Connect
    return Connection(*args, **kwargs)
    File "C:\Users\luvch\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\MySQLdb\connections.py", line 185, in __init__
    super().__init__(*args, **kwargs2)
    TypeError: connect() argument 3 must be str, not list
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Any help with this will be much appreciated

Answer 1

Looks like a simple typo, you're loading your database config details as db = yaml.load(open('db.yaml') but not referring to that in the app.config :

app.config['MYSQL_PASSWORD'] = ['mysql_password']
app.config['MYSQL_DB'] = ['mysql_db']

It should be:

app.config['MYSQL_PASSWORD'] = db['mysql_password']
app.config['MYSQL_DB'] = db['mysql_db']