如何使用 Kivy 和 Python 访问 class 之外的数据列表

Question

I am trying to create a grid and want to retrieve the data of users in a list I am parallelly working on mysql as well so as to add the data in it so I basically want to get access to the data list which I have used in the pressed method in the AppLayout Class so as to go ahead.

import kivy
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.gridlayout import GridLayout
from kivy.uix.textinput import TextInput
from kivy.uix.button import Button


class Applayout(GridLayout):

    def __init__(self , **kwargs): 

        super(Applayout , self).__init__(**kwargs)
        

        self.cols = 1

        self.inside = GridLayout()
        self.inside.cols = 2

        self.inside.add_widget(Label(text = "First Name: "))
        self.first_name = TextInput(multiline = False)
        self.inside.add_widget(self.first_name)

        self.inside.add_widget(Label(text = "Last Name: "))
        self.last_name = TextInput(multiline = False)
        self.inside.add_widget(self.last_name)

        self.inside.add_widget(Label(text = "Email: "))
        self.email = TextInput(multiline = False)
        self.inside.add_widget(self.email)

        self.add_widget(self.inside)

        self.submit = Button(text = "Submit", font_size = 40)
        self.submit.bind(on_press = self.pressed) 
        self.add_widget(self.submit)

    def pressed(self , instance):
        first_name = self.first_name.text
        last_name = self.last_name.text
        email = self.email.text

        person_data = {"First Name": first_name , "Last Name": last_name , "E-Mail": email}
        data = []
        data.append(person_data)

        print(f"Name: {first_name} {last_name} , E-Mail: {email} ")
        print("Submitted")

        self.first_name.text = ""
        self.last_name.text = ""
        self.email = ""


class Granth_BagadiaApp(App):
    def build(self):
        return Applayout()



if __name__  == "__main__":
    Granth_BagadiaApp().run()

class MyApp(App):
    def build(self):
        return MyGrid()
    def datas(self):
        return MyGrid().data

This is what I did But now how do I print this Cause on typing print(MyApp().datas()) I get [{'Name': <ObjectProperty name=nameee>, 'E-Mail': <ObjectProperty name=emailll>}]

Answer 1

All depends how you want to use it.

---

Normally I would run directly function with SQL and send data as argument.

class Applayout()

    def pressed(self, instance):
        data = [{
            "First Name": self.first_name.text, 
            "Last Name": self.last_name.text, 
            "E-Mail": self.email.text
        }]

        function_with_sql(data)
        #other_object.function_with_sql(data)

        # ... other code ...

Eventually I would use queue to communicate with other process.

class Applayout()

    def pressed(self, instance):
        data = [{
            "First Name": self.first_name.text, 
            "Last Name": self.last_name.text, 
            "E-Mail": self.email.text
        }]

        queue_to_other_process.put(data)

        # ... other code ...

---

But if I would have to give access to data then first I would use self.data

class Applayout()

    def __init___(...):
        self.data = [] # default value at start 

        # ... other code ...

    def pressed(self, instance):
        self.data = [{
            "First Name": self.first_name.text, 
            "Last Name": self.last_name.text, 
            "E-Mail": self.email.text
        }]

        # ... other code ...

and I would assign class to global variable

applayout = Applayout()

class Granth_BagadiaApp(App):
    def build(self):
        return applayout

and now everyone can access data as applayout.data .

---

Eventaully I would create data as external object and send data to Applayout and other classes as argument.

data = []

class Applayout()

    def __init___(..., data):
        self.data = data   
        
        # ... other code ...
        
    def pressed(self, instance):
        self.data.clear()  # not `self.data = []` because it will remove access to external `data`
        
        self.data.append({
            "First Name": self.first_name.text, 
            "Last Name": self.last_name.text, 
            "E-Mail": self.email.text
        })

        # ... other code ...

applayout = Applayout(data)

class Granth_BagadiaApp(App):
    def build(self):
        return applayout

Of course with external data you could use data directly in classes - without sending it as argument - but as says The Zen of Python "Explicit is better than implicit." - and it means data as argument.