in __init__ word=self.search_box.text AttributeError: 'NoneType' object has no attribute 'text'

Question

I am making an application.as far as I know I am doing thingd correctly but still getting this error

word=self.search_box.text AttributeError: \'NoneT

Answer 1

the problem is caused because the children are not stuck in the constructor of the parent, it does it an instant later so search_box will be None in the constructor, the solution is to execute it an instant after finishing the constructor with the help of Clock:

from kivy.clock import Clock


class DisplayPage(Screen):
    search_box= ObjectProperty()
    label_maening=StringProperty()
    label_synonym=StringProperty()
    label_ant=StringProperty()
    label_sentence=StringProperty()


    def __init__(self, **kwargs):
        super(DisplayPage,self).__init__(**kwargs)
        Clock.schedule_once(self.callback)

    def callback(self, dt):
        with open('vocab_words.json') as rfile:
            data=json.load(rfile)

        word=self.search_box.text               #the error occurred here 

        for value in data:
            if value['word']==word:
                self.label_maening=value['meaning']
                self.label_synonym=value['synonym']
                self.label_ant=value['antonyms']
                self.label_sentence=value['sentence']