如何在Kivy（Python3）中动态创建多个函数？

Question

Situation

I am creating a meeting finder app that will search through a JSON file and return a list of multiple meeting dictionaries. And I want to create buttons for each of the meetings so that I could know more information about the meeting or join the meeting. Since I need to query the meetings list, so I don't know how many meetings button will be there. I need to generate and bind those buttons dynamically.

Python Code

Only adding that part of the code which is causing the problem.

class MeetingDisplayer(Screen):
    def __init__(self,back,info,**kwargs):
        super().__init__(**kwargs)
        self.back = back
        self.info = info   # this is the meetings list which contains multiple meeting dictionaries.

        self.headings = [] # this will contain the text of the buttons
        for meeting in self.info:
            meeting_subject = meeting["meeting_subject"]
            meeting_organizer = meeting["meeting_organizer"]
            time = meeting["time"]
            heading = f"{meeting_subject} | {meeting_organizer} | {time}"
            self.headings.append([heading,None])
            
        
        self.scroller = ScrollView()
        self.scroller.pos_hint = {"x": 0.1, "top": 0.75}
        self.scroller.size_hint = (0.8, 0.63)
        
        self.info_grid = GridLayout()
        self.info_grid.cols = 1
        if len(self.headings) > 20:
            self.info_grid.size_hint = 1, 2
        elif len(self.headings) > 10:
            self.info_grid.size_hint = 1, 1.4
        elif len(self.headings) > 5: 
            self.info_grid.size_hint = 1, 0.8
        else:
            self.info_grid.size_hint = 1, 0.35
        
        i = -1
        for heading in self.headings:
            i += 1
            heading[1] = Button(text = heading[0], font_size = 15, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1), on_release = lambda x: self.find_function(i))
            self.info_grid.add_widget(heading[1])

        self.scroller.add_widget(self.info_grid)
        self.add_widget(self.scroller)
     
        
    def find_function(self, i):
        sm.add_widget(MeetingInformation(self.info, name = "MeetingInformation"))
        MeetingInformation_screen = sm.get_screen('MeetingInformation')
        setattr(MeetingInformation_screen, "index", i)
        sm.transition = SlideTransition(direction = "left")
        sm.current = "MeetingInformation"


class MeetingInformation(Screen):
    def __init__(self, meeting_list, **kwargs):
        super().__init__(**kwargs)
        self.meeting_list  = meeting_list

    def on_pre_enter(self):
        print(self.index)
        meeting = self.meeting_list[self.index]        

        self.info_grid = GridLayout()
        self.info_grid.cols = 2
        self.info_grid.size_hint = 0.9, 0.4
        self.info_grid.pos_hint = {"x": 0.05, "top": 0.67}
        self.category_label = Button(text = "Category:", font_size = 14, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1))
        self.info_grid.add_widget(self.category_label)
        self.category_value = Label(text = meeting["category"], font_size = 14, color = (0,0,0,1))
        self.info_grid.add_widget(self.category_value)
        self.time_label = Button(text = "Time:", font_size = 14, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1))
        self.info_grid.add_widget(self.time_label)
        self.time_value = Label(text = meeting["time"], font_size = 14, color = (0,0,0,1))
        self.info_grid.add_widget(self.time_value)
        self.subject_label = Button(text = "Subject:", font_size = 14, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1))
        self.info_grid.add_widget(self.subject_label)
        self.subject_value = Label(text = meeting["meeting_subject"], font_size = 14, color = (0,0,0,1))
        self.info_grid.add_widget(self.subject_value)
        self.organizer_label = Button(text = "Organizer:", font_size = 14, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1))
        self.info_grid.add_widget(self.organizer_label)
        self.organizer_value = Label(text = meeting["meeting_organizer"], font_size = 14, color = (0,0,0,1))
        self.info_grid.add_widget(self.organizer_value)
        self.meeting_id_label = Button(text = "Meeting ID:", font_size = 14, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1))
        self.info_grid.add_widget(self.meeting_id_label)
        self.meeting_id_value = Label(text = str(meeting["meeting_id"]), font_size = 14, color = (0,0,0,1))
        self.info_grid.add_widget(self.meeting_id_value)
        self.passcode_label = Button(text = str("Meeting Passcode:"), font_size = 14, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1))
        self.info_grid.add_widget(self.passcode_label)
        self.passcode_value = Label(text = meeting["passcode"], font_size = 14, color = (0,0,0,1))
        self.info_grid.add_widget(self.passcode_value)
        self.activation_status_label = Button(text = "Activation Status:", font_size = 14, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1))
        self.info_grid.add_widget(self.activation_status_label)
        self.activation_status_value = Label(text = str(meeting["active"]), font_size = 14, color = (0,0,0,1))
        self.info_grid.add_widget(self.activation_status_value)
        self.add_widget(self.info_grid)

But the problem is when I clicked a button, I can only get the last button widget that I added. I mean the i variable which is the index attribute is set to a fixed number [the index of the last button] and it can not identify which button is pressed.

Some pictures which can help

all buttons are here

after pressing the first button

after pressing the second button

Question

How can I bind the buttons with the function in a dynamic manner so that each time I press a button, I get the exact index of that button or display the exact information?

Answer 1

Try changing:

heading[1] = Button(text = heading[0], font_size = 15, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1), on_release = lambda x: self.find_function(i))

to:

heading[1] = Button(text = heading[0], font_size = 15, color = (1,1,1,1), background_color = (0/255, 153/255, 204/255, 1), on_release = lambda x, j=i: self.find_function(j))

The lambda function evaluates the i when the lambda is called (by the button press). Changing to lambda x, j=i: self.find_function(j) forces the evaluation of i when the `lambda is created.