main.py

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.gridlayout import GridLayout
from kivy.uix.recycleview import RecycleView
from kivy.uix.modalview import ModalView
from kivy.uix.textinput import TextInput
from kivy.properties import ObjectProperty, StringProperty, NumericProperty

import db

Builder.load_string("""
<ItemsGrid>:
    cols: 4
    Label:
        text: root.title
    Label:
        text: root.current
    Label:
        text: root.lowest
    Button:
        size_hint_x: 0.25
        text: 'x'
        
<AllItemsTable>:
    viewclass: 'ItemsGrid'
    RecycleBoxLayout:
        default_size: None, dp(56)
        default_size_hint: 1, None
        size_hint_y: None
        height: self.minimum_height
        orientation: 'vertical'
        
<AppContainer>
    Label:
        text: "Price Checker"
        size_hint_y: 0.05
        pos_hint: {'top': 1}
    AllItemsTable:
        pos_hint: {'top': 0.9}
    Button:
        text: '+'
        size_hint: (0.1, 0.1)
        pos_hint: {'right': 1}
        on_press: root.add_url_modal.open()
        
<AddUrlModal>
    size_hint: (0.25, 0.10)
    BoxLayout:
        orientation: 'vertical'
        TextInput:
            id: url
            size_hint_y: 0.50
            hint_text: "URL"
        BoxLayout:
            size_hint_y: 0.50
            orientation: 'horizontal'
            Button:
                text: "Add"
                on_release: root.add_url(url.text)
            Button:
                text: "Cancel"
                on_release: root.dismiss()
""")


class ItemsGrid(GridLayout):
    title = StringProperty('Item')
    current = StringProperty('Current')
    lowest = StringProperty('Lowest')
    pass


class AllItemsTable(RecycleView):
    def __init__(self, **kwargs):
        self.data = [{'title': str(x), 'current': str(x+1), 'lowest': str(x+10)} for x in range(5)]


class AddUrlModal(ModalView):
    def add_url(self, url):
        print(url)
        db.add_url(url)


class AppContainer(FloatLayout):
    add_url_modal = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(AppContainer, self).__init__(**kwargs)
        self.add_url_modal = AddUrlModal()

    def print_info(self):
        print("Hello")


class PriceApp(App):
    def build(self):
        return AppContainer()


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