Develop Reference

Geeting error in reading a file and pronting it as Label in kivy

I am trying to read text from a file and show it as Label in another screen but i am getting error that text file's content in not str even after using str() function.
Error:
ValueError: Screen1.usename accept only str
from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.lang import Builder
from kivy.properties import StringProperty
class Screen1(Screen):
def gb(self):
f=open('test.txt','r')
b=f.read()
t=str(b)
return t
usename = StringProperty("")
class Screen2(Screen):
username = StringProperty("")
root = Builder.load_string('''
<Screen1>:
BoxLayout:
orientation: "vertical"
Button:
text:'ue'
on_release: root.usename = root.gb; root.manager.current = "screen2"
<Screen2>:
name: "screen2"
Label:
text: root.username
ScreenManager:
Screen1:
id: loginscreen
Screen2:
username: loginscreen.usename
''')
class MyApp(App):
def build(self):
return root
r=MyApp()
r.run()

Your code:
on_release: root.usename = root.gb
is trying to set the usename to a method (root.gb). You probably want to set usename to the return value of that method. Try just adding (), like this:
on_release: root.usename = root.gb()

I finally solved the issue, this's how we can read a text file and display it as label in another screen in kivy.
from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.lang import Builder
from kivy.properties import StringProperty
class Screen1(Screen):
f=open('test.txt','r')
t=f.readlines()
b=t[0]
f.close()
class Screen2(Screen):
username = StringProperty("")
root = Builder.load_string('''
<Screen1>:
name:'xy'
id:loginscreen
BoxLayout:
orientation: "vertical"
Button:
text:'Execution button'
on_release: root.manager.current = "screen2"
<Screen2>:
name: "screen2"
FloatLayout:
Label:
text: root.username
Button:
text:'Back to menu'
size_hint:.3,.3
on_release: root.manager.current = "xy"
ScreenManager:
Screen1:
id:loginscreen
Screen2:
username: loginscreen.b
''')
class MyApp(App):
def build(self):
return root
r=MyApp()
r.run()

Kivy Inherit ScreenManager from FloatLayout

I am having trouble understanding how to inherit the functionality of one class into another with Kivy. I understand the error message ('LoadDialog_Directory' object has no attribute 'manager'), but I'm just not grasping exactly how to fix it. I believe I need to do something with the function below, but ultimately, I do not know.
def __init__(self, **kwargs):
super().__init__(**kwargs)
The goal of this script is to be able to select a specific driver as the path for the filechooser. I choose this method vs. others because most were using Kivy 1.11.1, this version has a lot of deprecated functions that do not work with 2.0.
.py
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang.builder import Builder
from kivy.uix.spinner import SpinnerOption
from kivy.uix.popup import Popup
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.properties import ObjectProperty
from kivy.utils import platform
from kivy.properties import StringProperty
import os
import string
class WindowManager(ScreenManager):
pass
class MyOption(SpinnerOption):
pass
class LoadDialog_Directory(FloatLayout):
load = ObjectProperty(None)
cancel = ObjectProperty(None)
def dir_driver(self):
x = self.manager.get_screen("first")
return str(x.ids.drive_dir.text)
class FirstWindow(Screen):
def get_drives(self):
drives = ['%s:' % d for d in string.ascii_uppercase if os.path.exists('%s:' % d)]
return drives
def dismiss_popup(self):
self._popup.dismiss()
def show_load_directory(self):
content = LoadDialog_Directory(load=self.directroy_path, cancel=self.dismiss_popup)
self._popup = Popup(title="Load file", content=content, size_hint=(0.9, 0.9))
self._popup.open()
def directroy_path(self, path, filename):
self.ids.text_input_directory.text = str(filename[0])
self.dismiss_popup()
kv_main = Builder.load_file('main.kv')
#
class MyApp(App):
def build(self):
return kv_main
if __name__ == '__main__':
MyApp().run()
main.kv
#:include first.kv
WindowManager:
FirstWindow:
<LoadDialog_Directory>:
BoxLayout:
size: root.size
pos: root.pos
orientation: "vertical"
FileChooserListView:
id: filechooser
dirselect: True
path: root.dir_driver()
BoxLayout:
size_hint_y: None
height: 30
Button:
text: "Cancel"
on_release: root.cancel()
Button:
text: "Load"
on_release: root.load(filechooser.path, filechooser.selection)
first.kv
<FirstWindow>
name: 'first'
GridLayout:
cols: 1
BoxLayout:
orientation: "horizontal"
TextInput:
BoxLayout:
orientation: "horizontal"
Spinner:
id: drive_dir
text: "Root Drive"
halign: 'center'
option_cls: "MyOption"
values: root.get_drives()
Button:
text: "Set Result Directory"
on_release: root.show_load_directory()
TextInput:
id: text_input_directory
disabled: True
text: text_input_directory.text
BoxLayout:
size_hint: (0.01, 1)
orientation: "horizontal"
TextInput:
Side Note: The reason for the extra blank TextInput is because the Spinner will not function (show drivers) if it is taking too much of the App.

After a few hours of trail and error I finally got it to work, but I have no idea why it works. Here is what changed:
New variable in class LoadDialog_Directory(FloatLayout) - input_pth
Called input_pth into my content variable within class FirstWindow(Screen) function show_load_directory(self)
Set my filechooser.path to root.input_pth in the main.kv file.
I do not understand how the input_pth variable within content is able to reference the class LoadDialog_Directory(FloatLayout) without having to pass something like:
def __init__(self, input_pth, **kwargs):
super(LoadDialog_Directory, self).__init__()
self.input_pth = input_pth
.py
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang.builder import Builder
from kivy.uix.spinner import SpinnerOption
from kivy.uix.popup import Popup
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.properties import ObjectProperty
from kivy.utils import platform
from kivy.properties import StringProperty
import os
import string
class WindowManager(ScreenManager):
pass
class MyOption(SpinnerOption):
pass
class LoadDialog_Directory(FloatLayout):
input_pth = StringProperty()
load = ObjectProperty()
cancel = ObjectProperty()
class FirstWindow(Screen):
def drive_list(self):
drives = ['%s:' % d for d in string.ascii_uppercase if os.path.exists('%s:' % d)]
return drives
def dismiss_popup(self):
self._popup.dismiss()
def show_load_directory(self):
content = LoadDialog_Directory(load=self.directroy_path, cancel=self.dismiss_popup, input_pth=self.ids.drive_dir.text)
self._popup = Popup(title="Load file", content=content, size_hint=(0.9, 0.9))
self._popup.open()
def directroy_path(self, path, filename):
self.ids.text_input_directory.text = str(filename[0])
self.dismiss_popup()
kv_main = Builder.load_file('main.kv')
#
class MyApp(App):
def build(self):
return kv_main
if __name__ == '__main__':
MyApp().run()
main.kv
#:include first.kv
WindowManager:
FirstWindow:
<LoadDialog_Directory>:
BoxLayout:
size: root.size
pos: root.pos
orientation: "vertical"
FileChooserListView:
id: filechooser
dirselect: True
path: root.input_pth
BoxLayout:
size_hint_y: None
height: 30
Button:
text: "Cancel"
on_release: root.cancel()
Button:
text: "Load"
on_release: root.load(filechooser.path, filechooser.selection)
first.kv
<FirstWindow>
name: 'first'
GridLayout:
cols: 1
BoxLayout:
orientation: "horizontal"
TextInput:
BoxLayout:
orientation: "horizontal"
Spinner:
id: drive_dir
halign: 'center'
option_cls: "MyOption"
values: root.drive_list()
Button:
text: "Set Result Directory"
on_release: root.show_load_directory()
TextInput:
id: text_input_directory
disabled: True
text: text_input_directory.text
BoxLayout:
size_hint: (0.01, 1)
orientation: "horizontal"
TextInput:

Add a widget that was created in kv from py

Is there a way to reference a custom widget from the py file?
I made a widget in kv, but I want to reference it from py, then add it again to another widget in kv.
I tried doing this using id but I got an error (KeyError: 'words_entry').
This is what I tried:
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.properties import ObjectProperty
from kivy.uix.textinput import TextInput
import os
class GetCount(Screen):
count_input = ObjectProperty(None)
def next(self):
# Setup next screen
text_inputs = [self.ids.words_entry for i in range(int(self.count_input.text))]
for text_input in text_inputs:
self.manager.ids.get_input.ids.grid.add_widget(text_input)
# Switch to next screen
self.manager.current = "get_input"
class GetInput(Screen):
pass
kv_file = Builder.load_string("""
ScreenManager:
GetCount:
name: "get_count"
id: get_count
GetInput:
name: "get_input"
id: get_input
<WordEntry#TextInput>:
id: words_entry
multiline: False
size_hint: (self.width, None)
<GetCount>:
count_input: count_input
FloatLayout:
Label:
text: "count"
size_hint: 1, 0.05
pos_hint: {"top":0.9}
TextInput:
id: count_input
size_hint: 0.8, 0.05
pos_hint: {"top":0.7, "x":0.1}
multiline: False
Button:
text: "Next"
on_release: root.next()
size_hint: 0.8, 0.05
pos_hint: {"top":0.5, "x":0.1}
<GetInput>:
ScrollView:
GridLayout:
size_hint_y: None
height: self.minimum_height
id: grid
cols: 1
""")
class MainApp(App):
def build(self):
return kv_file
if __name__ == "__main__":
app = MainApp()
app.run()
In this code, I want to add WordEntry to the GridLayout in GetInput from py (the reason is that I need to add multiple depending on the user's input).

You can use Factory to create an instance of a class that has been defined in kv. So your GetCount class can be:
from kivy.factory import Factory
class GetCount(Screen):
count_input = ObjectProperty(None)
def next(self):
# Setup next screen
for _ in range(int(self.count_input.text)):
new_word_entry = Factory.WordEntry()
self.manager.ids.get_input.ids.grid.add_widget(new_word_entry)
# Switch to next screen
self.manager.current = "get_input"

How can I add an amount of widgets in the kv file based on user input?

I'm trying to make a program that puts x amount of TextInputs based on the user's input. I can do that in the py file, but how do I do this in the kv file? I also need to be able to reference these TextInputs later on.
This is what I have so far:
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.properties import ObjectProperty
from kivy.uix.textinput import TextInput
class GetCount(Screen):
count_input = ObjectProperty(None)
def next(self):
# Setup next screen
text_inputs = [TextInput(multiline=False) for i in range(int(self.count_input.text))]
for text_input in text_inputs:
self.manager.ids.get_input.ids.grid.add_widget(text_input)
# Switch to next screen
self.manager.current = "get_input"
class GetInput(Screen):
pass
kv_file = Builder.load_string("""
ScreenManager:
GetCount:
name: "get_count"
id: get_count
GetInput:
name: "get_input"
id: get_input
<GetCount>:
count_input: count_input
FloatLayout:
Label:
text: "count"
size_hint: 1, 0.05
pos_hint: {"top":0.9}
TextInput:
id: count_input
size_hint: 0.8, 0.05
pos_hint: {"top":0.7, "x":0.1}
multiline: False
Button:
text: "Next"
on_release: root.next()
size_hint: 0.8, 0.05
pos_hint: {"top":0.5, "x":0.1}
<GetInput>:
FloatLayout:
GridLayout:
id: grid
cols: 1
""")
class MainApp(App):
def build(self):
return kv_file
if __name__ == "__main__":
app = MainApp()
app.run()
The problem is, the TextInputs are being added and created by the py code, how can I create the widget in kv and then add it in py?

Kivy - Adding Buttons To Screen Through Python

I am trying to make a screen view with buttons. The problem is that the amount of buttons needed each time will change, therefore I am not able to use the kv file to make theses buttons. I am having trouble adding buttons through the normal python code. Any help is appreciated.
import kivy
import webbrowser
import MSQLHandler
kivy.require('1.10.0')
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.gridlayout import GridLayout
from kivy.uix.button import Label
from kivy.uix.widget import Widget
from kivy.uix.listview import ListItemButton
from kivy.properties import ObjectProperty
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen, SlideTransition, CardTransition, SwapTransition, FadeTransition, WipeTransition, FallOutTransition, RiseInTransition, NoTransition
from kivy.lang import Builder
from kivy.uix.button import Button
class Login_Failed(Screen):
def changeScreen(self, next_screen):
self.manager.current = next_screen
class Loged_In(Screen):
def changeScreen(self, next_screen):
self.manager.current = next_screen
class Registers(Screen):
def changeScreen(self, next_screen):
self.manager.current = next_screen
class Login_Screen(Screen):
teacher_connect_image = ObjectProperty()
username_text_input = ObjectProperty()
password_text_input = ObjectProperty()
teacherid_text_input = ObjectProperty()
def LoginButton(self):
if self.teacherid_text_input.text == "":
Number = 0
else:
Number = int(self.teacherid_text_input.text)
MSQLHandler.LoginSystem(self.username_text_input.text, self.password_text_input.text, Number)
def changeScreen(self, next_screen):
self.manager.current = next_screen
if MSQLHandler.LoginSystem(self.username_text_input.text, self.password_text_input.text, Number) is True:
print("Returns True")
changeScreen(self, "Loged_In")
elif MSQLHandler.LoginSystem(self.username_text_input.text, self.password_text_input.text, Number) is False:
print("Returns False")
changeScreen(self, "Login_Failed")
else:
print("Null")
class ScreenManagerr(ScreenManager):
pass
class MainKivyFrameApp(App):
def build(self):
Registers().add_widget(Button(text="Helpp"))
return ScreenManagerr()
mainFrame = MainKivyFrameApp()
mainFrame.run()
If you look to where the app is being built, you will see: Registers().add_widget(Button(text="Helpp"))
This is where I have tried to add a Button to the screen of Registers. This doesn't give me any errors, but it still does not show the button.

Solution
In the kv file, add an event (on_enter or on_pre_enter) in each screen and bind it to a callback method as shown in the following snippets and example. Remember to remove the widgets that were added dynamically before leaving the current screen, by adding an event (on_leave or on_pre_leave).
Snippets
<Registers>:
on_pre_enter: self.add_buttons(n)
on_leave: self.remove_buttons()
Example
main.py
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.button import Button
from kivy.core.window import Window
from kivy.properties import ObjectProperty, NumericProperty
class MyScreenManager(ScreenManager):
total_button = NumericProperty(2)
class Login(Screen):
login = ObjectProperty(None)
def on_pre_enter(self):
Window.size = (400, 300)
def check_password(self, instance, password):
if password == "pwd":
instance.current = "registers"
class Registers(Screen):
container = ObjectProperty(None)
def on_pre_enter(self):
Window.size = (800, 600)
def add_buttons(self, n):
print("Registers: n={}".format(n))
for i in range(n):
self.container.add_widget(Button(text="Button #{}".format(i), id=str(i)))
def remove_buttons(self, *args):
for child in [child for child in self.container.children]:
self.container.remove_widget(child)
class Welcome(Screen):
pass
class TestApp(App):
title = "ScreenManager - Add Widgets Dynamically"
def build(self):
return MyScreenManager()
if __name__ == "__main__":
TestApp().run()
test.kv
#:kivy 1.10.0
#:import SwapTransition kivy.uix.screenmanager.SwapTransition
<MyScreenManager>:
transition: SwapTransition()
Login:
Registers:
on_pre_enter:
self.add_buttons(app.root.total_button)
on_leave:
self.remove_buttons()
Welcome:
<Login>:
id: login
name: "login"
login: login
GridLayout:
size_hint: (0.5, 0.5)
pos_hint: {"center_x": 0.5, "center_y": 0.6}
rows: 3
padding: 20
Label:
size_hint: (0.2, 0.2)
text:"Password:"
font_size: 30
halign: "center"
valign: "middle"
TextInput:
id: password
size_hint: (0.2, 0.06)
cursor_blink: True
font_size: 20
multiline: False
password: True
Button:
text: "Continue"
size_hint: (0.2, 0.08)
on_release:
root.login.check_password(root.manager, password.text)
<Registers>:
name:'registers'
container: container
BoxLayout:
orientation: 'vertical'
Button:
text: 'Return to Login'
on_press: root.manager.current = 'login'
Button:
text: 'Next Screen'
on_press: root.manager.current = 'welcome'
BoxLayout:
id: container
orientation: 'vertical'
<Welcome>:
name:'welcome'
BoxLayout:
Label:
text: 'Welcome!'
Button:
text: 'Return to Registers'
on_press:
app.root.total_button = 5
root.manager.current = 'registers'
Output