kivy - Python : add validation in form

Question

Can someone tell me that how to set required validation on textInput
when click on Ok button?
At this time click on Ok button then i check every TextInput like that.
if self.name.text.strip() == "":
But if my form have more than 50 feilds then it will be very lengthy code?Can someone tell me another short way to set required validation on TextInput.

test.py

from kivy.uix.screenmanager import Screen
from kivy.app import App
from kivy.lang import Builder
from kivy.core.window import Window
from kivy.properties import ObjectProperty
from kivy.uix.textinput import TextInput
Window.size = (500, 330)

class FloatInput(TextInput):

    def __init__(self, **kwargs):
        super(FloatInput, self).__init__(**kwargs)

    def on_text(self, instance, text):
        if text !="":
            print(text)

class TestScreen(Screen):
    name = ObjectProperty(None)
    clas = ObjectProperty(None)

    def check_validation(self):
        if self.name.text.strip() == "":
            print("Name is blank")
        elif self.clas.text.strip() == "":
            print("clas is blank")



class Test(App):
    def build(self):
        self.root = Builder.load_file('test.kv')
        return self.root


if __name__ == '__main__':
    Test().run()

test.kv

#:kivy 1.10.0
TestScreen:
    name:name
    clas:clas

    GridLayout:
        cols: 2
        padding : 30,30
        spacing: 10, 10
        row_default_height: '40dp'

        Label:
            text: 'Name'

        FloatInput:
            id: name

        Label:
            text: 'Class'

        FloatInput:
            id: clas


        Button:
            text: 'Ok'
            on_release: root.check_validation()

        Button:
            text: 'Cancel'

Answer 1

1. Create a ScrollView of GridLayout
2. Use a loop to create each line of the form consisting of a Label and TextInput widgets
3. Use a loop to access child widget in self.container.children.

Please refer to the example below for details.

Example

main.py

from kivy.app import App
from kivy.core.window import Window
from kivy.uix.screenmanager import Screen
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
from kivy.metrics import dp
from kivy.properties import ObjectProperty, DictProperty

Window.size = (500, 330)


class FloatInput(TextInput):

    def on_text(self, instance, text):
        if text != "":
            print("id={0}, text={1}".format(instance.id, text))


class TestScreen(Screen):
    container = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(TestScreen, self).__init__(**kwargs)
        self.container.bind(minimum_height=self.container.setter('height'))
        self.create_form()

    def create_form(self):
        # create 50 labels and text inputs
        for i in range(50):
            label = Label(text="Label {}".format(i), size_hint_y=None, height=dp(40))
            text_input = FloatInput(id=str(i), hint_text="TextInput {}".format(i), size_hint_y=None, height=dp(40))
            self.container.add_widget(label)
            self.container.add_widget(text_input)

    def check_validation(self):
        for child in reversed(self.container.children):
            if isinstance(child, Label):
                label_text = child.text
            if isinstance(child, FloatInput):
                if child.text.strip() == "":
                    print("{0} - TextInput is blank, obj={1}".format(label_text, child))


class Test(App):
    def build(self):
        return TestScreen()


if __name__ == '__main__':
    Test().run()

test.kv

#:kivy 1.10.0

<TestScreen>:
    container: container

    BoxLayout:
        orientation: 'vertical'

        BoxLayout:
            orientation: 'vertical'

            ScrollView:

                GridLayout:
                    id: container
                    cols: 2
                    size_hint_y: None
                    padding : 30,30
                    spacing: 10, 10

        BoxLayout:
            size_hint_y: 0.2

            Button:
                text: 'Ok'
                on_release: root.check_validation()

            Button:
                text: 'Cancel'

Output