Argument 1 has unexpected type 'NoneType'?

Question

I have a problem with my PyQt button action. I would like to send a String with the Function but I got this Error:

TypeError: argument 1 has unexpected type 'NoneType'

import sys

from PyQt5.QtWidgets import QApplication, QPushButton, QAction
from PyQt5.QtCore import QObject, pyqtSignal
from PyQt5.QtGui import *
from PyQt5.uic import *

app = QApplication(sys.argv)
cocktail = loadUi('create.ui')

def mixCocktail(str):
      cocktail.show()
      cocktail.showFullScreen()
      cocktail.lbl_header.setText(str)


widget = loadUi('drinkmixer.ui')

widget.btn_ckt1.clicked.connect(mixCocktail("string"))

widget.show()
sys.exit(app.exec_())

Traceback (most recent call last): File "------\drinkmixer.py", line 27, in widget.btn_ckt1.clicked.connect(mixCocktail("string")) TypeError: argument 1 has unexpected type 'NoneType' — Darkdrummer, Dec 05 '16 at 20:16
Ah. That's because you aren't returning anything from `mixCocktail()`. — user3030010, Dec 05 '16 at 20:19
From looking at some example online, it looks like it expects a callable function. In which case you should replace that argument with `lambda: micCocktail("string")` — user3030010, Dec 05 '16 at 20:20
If you ever need to do that with a multi-arguments function, lambda won't work but you can use the `partial` library and connect your signal and function like so: `.connect(partial(my_function, arg1=..., arg2=...))` — Guimoute, Mar 04 '19 at 10:24

score 25 · Answer 1 · edited May 16 '21 at 08:48

25

As suggested by user3030010 and ekhumoro it expects a callable function. In which case you should replace that argument with lambda: mixCocktail("string") AND ALSO don't use str it's a python built-in datatype I have replaced it with _str

import sys

from PyQt5.QtWidgets import QApplication, QPushButton, QAction
from PyQt5.QtCore import QObject, pyqtSignal
from PyQt5.QtGui import *
from PyQt5.uic import *

app = QApplication(sys.argv)
cocktail = loadUi('create.ui')

def mixCocktail(_str):
      cocktail.show()
      cocktail.showFullScreen()
      cocktail.lbl_header.setText(_str)
      

widget = loadUi('drinkmixer.ui')

widget.btn_ckt1.clicked.connect(lambda: mixCocktail("string"))

widget.show()
sys.exit(app.exec_())

More about lambda functions: What is a lambda (function)?

edited May 16 '21 at 08:48

tyrudani

3
3

answered Dec 05 '16 at 20:20

harshil9968

3,254
1
16
26

2

`str` is not a keyword - it's a built-in type. – ekhumoro Dec 05 '16 at 21:23
Thanks for rectifying, I knew I was writing something wrong. – harshil9968 Dec 05 '16 at 21:25
2

This answer is completely wrong. The correct solution was given in the [comment by user3030010](http://stackoverflow.com/questions/40982518/argument-1-has-unexpected-type-nonetype#comment69174849_40982518). – ekhumoro Dec 05 '16 at 21:28
@ekhumoro rectified. – harshil9968 Dec 05 '16 at 21:34
1

made it wiki as it was from both of your assistance. – harshil9968 Dec 05 '16 at 21:35

score 2 · Answer 2 · answered Apr 08 '21 at 21:18

2

instead of this

widget.btn_ckt1.clicked.connect(mixCocktail("string"))

write

widget.btn_ckt1.clicked.connect(lambda:mixCocktail("string"))

answered Apr 08 '21 at 21:18

damanpreet singh

109
2
5

Argument 1 has unexpected type 'NoneType'?

2 Answers2

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