Develop Reference

I want to load text from text field in .kv file to a variable in .py file

I want to be able to click on MDFlatButton that says Štart and i want it to let's say for an example to call get_user_input(self) which would print whatever is inside text field. And I have been struggling with this for 2 whole days and i have no idea what to do, I am just a beginner and I have no clue what am I doing so sorry if it's messy. Ty for help, those are my files:
main.py file:
from kivy.core.window import Window
from kivy.lang import Builder
from kivy.properties import ObjectProperty
from kivymd.app import MDApp
from kivy.uix.screenmanager import Screen, ScreenManager
from kivymd.uix.menu import MDDropdownMenu
from kivymd.uix.textfield import MDTextField
from kivy.properties import StringProperty
class testy(Screen):
novy_test = ObjectProperty()
class Test(MDApp):
Window.size = (1170 / 3, 2532 / 3)
# input_number = ObjectProperty()
def build(self):
self.theme_cls.material_style = "M3"
self.theme_cls.theme_style = "Dark"
self.theme_cls.primary_palette = 'Gray'
return testy()
def get_user_input(self):
print(self.root.ids.my_textfield_1.ids.user.text)
def callback(self, button):
pass
class CustomOverFlowMenu(MDDropdownMenu):
# In this class you can set custom properties for the overflow menu.
pass
Test().run()
test.kv file:
#:import Factory kivy.factory.Factory
#:import CustomOverFlowMenu __main__.CustomOverFlowMenu
<testy>:
name:'testy'
id: testy
MDBoxLayout:
orientation: "vertical"
MDTopAppBar:
title: "MDTopAppBar"
use_overflow: True
overflow_cls: CustomOverFlowMenu()
specific_text_color: .51,.51,.51,1
md_bg_color: 0, 0, 0, 1
left_action_items: [["car", lambda x: Factory.novy_test().open(), '',"Nový test"]]
MDBottomNavigation:
panel_color: "black"
selected_color_background: "white"
text_color_active: "lightgray"
selected_color_background: 1, 1, 1, .4
MDBottomNavigationItem:
name: 'screen 1'
text: 'Testy'
icon: 'road-variant'
MDLabel:
text: 'Test'
halign: 'center'
MDBottomNavigationItem:
name: 'screen 2'
text: 'chyby'
icon: 'alert-circle'
MDLabel:
text: 'Chyby'
halign: 'center'
MDBottomNavigationItem:
name: 'screen 3'
text: 'Settings'
icon: 'cog'
MDLabel:
text: 'LinkedIN'
halign: 'center'
<novy_test#Popup>:
id:my_textfield_1
size_hint: .8, .45
title: 'Nový test'
separator_color: 'black'
title_align: 'center'
BoxLayout:
id: layout
spacing: 10
orientation:'vertical'
MDTextField:
id: user
hint_text: "Číslo testu"
mode: "round"
pos_hint: {"top": 1}
MDFlatButton:
text: 'Štart'
pos_hint: {'center_x': .5}
on_press: app.get_user_input()
MDFlatButton:
pos_hint: {'center_x': .5}
text:'test z nesprávnych'
MDFlatButton:
text:'test z neurobených'
pos_hint: {'center_x': .5}
MDFlatButton:
text:'test z neurobených'
pos_hint: {'center_x': .5}
MDFlatButton:
text:'test z neurobených'
pos_hint: {'center_x': .5}

I didn't perfectly understand all that you wanted to do, but in this example, the text a person types into the box will print. I moved the .kv language into a string just for convenience of creating a one-file runnable project. I tested it.
The main point is this code, inside the .kv file/kivy language you can use the id property to get a reference to the objects, and then the .text property of that object is sent as an argument to the function.
on_press: app.get_user_input(user.text)
runnable:
from kivy.core.window import Window
from kivy.lang import Builder
from kivymd.app import MDApp
from kivy.uix.screenmanager import Screen, ScreenManager
from kivymd.uix.menu import MDDropdownMenu
from kivy.uix.popup import Popup
from kivymd.uix.textfield import MDTextField
from kivy.properties import StringProperty
Builder.load_string('''
#:import Factory kivy.factory.Factory
<testy>:
name:'testy'
id: testy
MDBoxLayout:
orientation: "vertical"
MDTopAppBar:
title: "MDTopAppBar"
use_overflow: True
# overflow_cls: CustomOverFlowMenu()
specific_text_color: .51,.51,.51,1
md_bg_color: 0, 0, 0, 1
left_action_items: [["car", lambda x: Factory.NovyTest().open(), '',"Nový test"]]
MDBottomNavigation:
panel_color: "black"
selected_color_background: "white"
text_color_active: "lightgray"
selected_color_background: 1, 1, 1, .4
MDBottomNavigationItem:
name: 'screen 1'
text: 'Testy'
icon: 'road-variant'
MDLabel:
text: 'Test'
halign: 'center'
MDBottomNavigationItem:
name: 'screen 2'
text: 'chyby'
icon: 'alert-circle'
MDLabel:
text: 'Chyby'
halign: 'center'
MDBottomNavigationItem:
name: 'screen 3'
text: 'Settings'
icon: 'cog'
MDLabel:
text: 'LinkedIN'
halign: 'center'
<NovyTest#Popup>:
id:my_textfield_1
size_hint: .8, .45
title: 'Nový test'
separator_color: 'black'
title_align: 'center'
BoxLayout:
id: layout
spacing: 10
orientation:'vertical'
MDTextField:
id: user
hint_text: "Číslo testu"
mode: "round"
pos_hint: {"top": 1}
MDFlatButton:
text: 'Štart'
pos_hint: {'center_x': .5}
# inside .kv/kivy language you can use the id property
on_press: app.get_user_input(user.text)
MDFlatButton:
pos_hint: {'center_x': .5}
text:'test z nesprávnych'
MDFlatButton:
text:'test z neurobených'
pos_hint: {'center_x': .5}
MDFlatButton:
text:'test z neurobených'
pos_hint: {'center_x': .5}
MDFlatButton:
text:'test z neurobených'
pos_hint: {'center_x': .5}
'''
)
class NovyTest(Popup):
# just an example, not used in this code
def __init__(self, **kw):
super().__init__(**kw)
class testy(Screen):
# can list objects defined in .kv file and give them a type hint corresponding to object type
novy_test: NovyTest
def __init__(self, **kw):
super().__init__(**kw)
print("creating screen testy")
# novy_test = ObjectProperty()
class Test(MDApp):
Window.size = (1170 / 3, 2532 / 3)
# input_number = ObjectProperty()
def build(self) -> testy:
self.theme_cls.material_style = "M3"
self.theme_cls.theme_style = "Dark"
self.theme_cls.primary_palette = 'Gray'
return testy()
def get_user_input(self, input_text, *args):
print(f"{self} user input: {input_text}")
# print(self.root.ids.my_textfield_1.ids.user.text)
def callback(self, button):
pass
class CustomOverFlowMenu(MDDropdownMenu):
# In this class you can set custom properties for the overflow menu.
pass
Test().run()
end

Python Kivy/kivyMD load second screen method in authentication page

I want to know the method of loading the second screen when authentication is passed.
I can call the second screen from the .kv file vi on_press or other methods. But I need to call from python code to check the authentication.
Can anyone help with my code?
Here is my code:
app.py
from kivy.lang import Builder
from kivymd.app import MDApp
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.screenmanager import Screen, ScreenManager
from kivy.properties import ObjectProperty
class my_layout(FloatLayout):
screen_mngr = ObjectProperty(None)
class myapp(MDApp):
def build(self):
self.theme_cls.theme_style = "Light"
self.theme_cls.primary_palette = "BlueGray"
return Builder.load_file("app.kv")
def logger(self):
if self.root.ids.user.text == 'admin' and self.root.ids.password.text=='admin':
self.root.ids.welcome_label.text = f'Sup {self.root.ids.user.text}!'
screen = Screen(name='screen2')
else:
self.root.ids.welcome_label.text = 'Wrong credentials'
if __name__ == "__main__":
myapp().run()
And here is my design kv file.
app.kv file:
my_layout:
screen_mngr: screen_mngr
ScreenManager:
id: screen_mngr
home: home
Screen:
id: home
name: 'home'
MDCard:
size_hint: None, None
size: 450, 600
pos_hint: {"center_x": 0.5, "center_y": 0.5}
elevation: 10
padding: 25
spacing: 25
orientation: 'vertical'
MDLabel:
id: welcome_label
text: "WELCOME"
font_size: 40
halign: 'center'
size_hint_y: None
height: self.texture_size[1]
padding_y: 15
MDTextField:
id: user
hint_text: "username"
icon_right: "account"
size_hint_x: None
width: 200
font_size: 18
pos_hint: {"center_x": 0.5}
MDTextField:
id: password
hint_text: "password"
icon_right: "eye-off"
size_hint_x: None
width: 200
font_size: 18
pos_hint: {"center_x": 0.5}
MDRoundFlatButton:
text: "LOG IN"
font_size: 12
pos_hint: {"center_x": 0.5}
on_press: screen2
Screen:
id: screen2
name: 'screen2'
MDRoundFlatButton:
text: "This is Second Screen\nGo to Screen1"
size_hint: 0.2,0.1
pos_hint: {"center_x":0.5,"y":0.5}
on_press: screen_mngr.current = "home"

A couple small problems:
First, in your kv you need to have your LOG IN Button call the code to handle the log in, like this:
MDRoundFlatButton:
text: "LOG IN"
font_size: 12
pos_hint: {"center_x": 0.5}
on_press: app.logger() # call the method that handles login
Then, in that method, you can change to the screen2 by using the current property of the ScreenManager, like this:
def logger(self):
if self.root.ids.user.text == 'admin' and self.root.ids.password.text=='admin':
self.root.ids.welcome_label.text = f'Sup {self.root.ids.user.text}!'
self.root.ids.screen_mngr.current = 'screen2' # go to screen2
# screen = Screen(name='screen2')
else:
self.root.ids.welcome_label.text = 'Wrong credentials'

Widgets Position not Fixed in APK file

I am new to kivy and i am very confuse to set the position of the widgets for mobile apllication
As i am using default size of the desktop window screen, In that widgets position look goods and in a proper allignment
i have attached PNG file of window screen and mobile screen
but when i use this in android apk file and installed in mobile, then all position of widgest are messed up and not looks to good for visibillity
so how to adjust the size and postion of widgets for android apk file
from kivymd.app import MDApp
from kivy.lang import Builder
from kivymd.uix.screen import MDScreen
from kivy.uix.screenmanager import ScreenManager
KV = ('''
<LOGIN_Window>:
name: 'login_window1'
FloatLayout:
MDToolbar:
title: 'permit me'
elevation: 10
pos_hint: {"left": 1, "top": 1}
MDLabel:
text: 'Welcome to permit me'
font_size: '35sp'
size: self.size
pos: self.pos
pos_hint: {'x': 0.21, 'y': 0.65}
size_hint_y: '0.35dp'
size_hint_x: '0.50dp'
BoxLayout:
orientation: 'vertical'
pos_hint: {'x': .25, 'y': 0.65}
size_hint: None, None
size_hint: '0.6dp', '0.08dp'
MDLabel:
text: 'Email-ID'
font_size: '15sp'
height: self.texture_size[1] + dp(10)
MDTextFieldRound:
id: login
hint_text: 'For Eg:- XXY...#gmail.com'
icon_left: "email"
input_type: 'text'
MDBoxLayout:
orientation: 'horizontal'
pos_hint: {'x':.25, 'y':4}
spacing: '50dp'
MDFillRoundFlatButton:
id: logIn
text: 'Login'
MDFillRoundFlatButton:
text: 'Register'
MDLabel:
text:'Powered By Technology'
pos_hint : {'x': 0,'y': 0}
size_hint_y: None
height: self.texture_size[1] + dp(10)
WindowManager:
LOGIN_Window:
'''
)
class LOGIN_Window(MDScreen):
pass
class WindowManager(ScreenManager):
pass
class MainApp(MDApp):
def build(self):
return Builder.load_string(KV)
if __name__ == '__main__':
MainApp().run()

Python - Kivy: KeyError with Text Input using ScreenManager

I'm working on a project using Kivy with ScreenManager (and KivyMD).
The reason for using this is my need of making an application with multiple screens. My goal is to get User Input from an existing MDTextField by (a string) ID and then Print it out.
However, I keep getting this Error: File "<string>", line 37, in <module> File "c:/Users/admin/Desktop/myApp/Main.py", line 75, in loginFunction username = mainScreenInstance.ids["input_username"].text KeyError: 'input_username'.
I have searched for answers all over the internet and StackOverflow, but no solution seems to work for me. Maybe there's someone who can help me with my problem and make my code work.
Anyway, here's my short & simple Code:
from kivymd.app import MDApp
from kivy.lang.builder import Builder
from kivy.uix.screenmanager import Screen, ScreenManager
import sys
screen_helper = """
ScreenManager:
MenuScreen:
name: 'menu'
SecondScreen:
name: 'second'
<MenuScreen>:
MDToolbar:
title: "Menu Screen"
pos_hint: {"top": 1}
anchor_title: "center"
md_bg_color: (0/255, 0/255, 0/255, 1)
Image:
source: "Logo_h_black.png"
pos_hint: {"center_x": 0.5, "center_y": 0.75}
size_hint_x: (0.25)
size_hint_y: (0.25)
MDTextField:
id: input_username
hint_text: "Username"
size_hint: (0.5, 0.1)
pos_hint: {"center_x": 0.5, "center_y": 0.55}
font_size: 20
mode: "rectangle"
MDTextField:
id: input_password
hint_text: "Password"
size_hint: (0.5, 0.1)
pos_hint: {"center_x": 0.5, "center_y": 0.45}
font_size: 20
mode: "rectangle"
MDFillRoundFlatButton:
text: "LOG IN"
font_size: 17
pos_hint: {"center_x": 0.5, "center_y": 0.25}
on_press: app.loginFunction()
<SecondScreen>:
MDLabel:
text: 'Profile'
halign: 'center'
MDRectangleFlatButton:
text: 'Back'
pos_hint: {'center_x':0.5,'center_y':0.1}
on_press: root.manager.current = 'menu'
"""
class MenuScreen(Screen):
pass
class SecondScreen(Screen):
pass
sm = ScreenManager()
sm.add_widget(MenuScreen(name='menu'))
sm.add_widget(SecondScreen(name='second'))
class myApp(MDApp):
def loginFunction(self, args=None):
if args is None:
args = sys.argv
mainScreenInstance = sm.get_screen('menu')
username = mainScreenInstance.ids["input_username"].text
password = mainScreenInstance.ids["input_password"].text
print (username)
print (password)
def build(self):
screen = Builder.load_string(screen_helper)
return screen
myApp().run()

The problem is that your loginFunction is trying to get the mainScreenInstance from sm, but sm is created before the screen_helper is loaded, so it doesn't know about the ids you have defined in your screen_helper. Also, that sm is not actually used as part of you GUI, it is just ignored (except for your reference to it in the loginFunction).
So, I recommend that you eliminate the following lines completely:
sm = ScreenManager()
sm.add_widget(MenuScreen(name='menu'))
sm.add_widget(SecondScreen(name='second'))
And change loginFunction to not use sm by replacing:
mainScreenInstance = sm.get_screen('menu')
with:
mainScreenInstance = self.root.get_screen('menu')

You're duplicating the widget definitions and then not using them in code. Finally, you're overwriting the Screen manager from the screen_helper string with a new instance. Tbh I did some of that when I started learning Kivy. The kv language is confusing at first but once you get it is beautiful. This version should work (I haven't tested it since I haven't found an easy way to install kivymd on my phone's dev env):
from kivymd.app import MDApp
from kivy.lang.builder import Builder
from kivy.uix.screenmanager import Screen
import sys
screen_helper = """
ScreenManager:
MenuScreen:
name: 'menu'
SecondScreen:
name: 'second'
<MenuScreen>:
MDToolbar:
title: "Menu Screen"
pos_hint: {"top": 1}
anchor_title: "center"
md_bg_color: (0, 0, 0, 1)
Image:
source: "Logo_h_black.png"
pos_hint: {"center_x": 0.5, "center_y": 0.75}
size_hint_x: (0.25)
size_hint_y: (0.25)
MDTextField:
id: input_username
hint_text: "Username"
size_hint: (0.5, 0.1)
pos_hint: {"center_x": 0.5, "center_y": 0.55}
font_size: 20
mode: "rectangle"
MDTextField:
id: input_password
hint_text: "Password"
size_hint: (0.5, 0.1)
pos_hint: {"center_x": 0.5, "center_y": 0.45}
font_size: 20
mode: "rectangle"
MDFillRoundFlatButton:
text: "LOG IN"
font_size: 17
pos_hint: {"center_x": 0.5, "center_y": 0.25}
on_press: app.loginFunction()
<SecondScreen>:
MDLabel:
text: 'Profile'
halign: 'center'
MDRectangleFlatButton:
text: 'Back'
pos_hint: {'center_x':0.5,'center_y':0.1}
on_press: root.manager.current = 'menu'
"""
class MenuScreen(Screen):
pass
class SecondScreen(Screen):
pass
class myApp(MDApp):
sm = None
def on_start():
self.sm = self.root
def loginFunction(self, args=None):
if args is None:
args = sys.argv
mainScreenInstance = self.sm.get_screen('menu')
username = mainScreenInstance.ids["input_username"].text
password = mainScreenInstance.ids["input_password"].text
print (username)
print (password)
# if self.is_login_correct(username, password):
# self.sm.current('second')
def build(self):
return Builder.load_string(screen_helper)
myApp().run()
Personally, I would move all login-related functions to the MenuScreen class, for consistency.

kivymd text field stills shows the hint_text in the field after typing

I am having trouble with MDTextField. It carries on displaying the hint inside the textfield while typing. I have tried setting the background color to hide it but that didn't work. I have looked at a few tutorials and everyone seems to be doing it the same way as me and it just works for other people so i feel i have done something really wrong.
Image of what happens this is my first post so i am not aloud to post images :)
Any help will be greatly appreciated. Thanks in advance.
main.py
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.core.window import Windowfrom kivy.config import Config
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.theming import ThemeManager
from kivy.lang import Builder
from kivymd.app import MDApp
from kivy.graphics import Rectangle, Color
import pymysql
class WelcomeScreen(Screen):
pass
class LoginScreen(Screen):
pass
class RegisterScreen(Screen):
pass
class WindowManager(ScreenManager):
pass
class MainApp(MDApp):
def build(self):
# theme_cls = ThemeManager()
return Builder.load_file("main.kv")
def change_screen(self, screen, direction):
self.root.transition.direction = direction
self.root.current = screen
if __name__ == "__main__":
MainApp().run()
main.kv
#: import Window kivy.core.window.Window
#: import MDLabel kivymd.uix.label.MDLabel
#: import Rectangle kivy.graphics.Rectangle
#: import Color kivy.graphics.Rectangle
WindowManager:
WelcomeScreen:
LoginScreen:
RegisterScreen:
<WelcomeScreen>:
name: "welcome_screen"
FloatLayout:
orientation: "vertical"
MDToolbar:
id: toolbar
title: "SecureIT 24/7"
pos_hint: {'top': 1}
Button:
text: 'Login'
color: 1, 1, 1, 1
size_hint: 0.25, 0.25
pos_hint: {"right":0.625, "top":0.80}
on_release:
app.root.current = "login_screen"
Button:
text: 'Register'
color: 1,1,1,1
size_hint: 0.25, 0.25
pos_hint: {"right":0.625, "top":0.55 }
on_release:
app.root.current = "register_screen"
<LoginScreen>:
name: "login_screen"
FloatLayout:
MDBanner:
id: banner
text: "Login"
# The widget that is under the banner.
# It will be shifted down to the height of the banner.
MDToolbar:
id: toolbar
title: "Login"
elevation: 10
pos_hint: {'top': 1}
left_action_items: [['arrow-left', lambda screen: app.change_screen('welcome_screen', 'right')]]
FloatLayout:
padding: [50,50,50,50]
spacing: 50
FloatLayout:
orientation: 'vertical'
Label:
text: 'Login'
font_size: 18
halign: 'center'
text_size: root.width-20, 20
color: 0,0,0,1
pos_hint: {"right":1, "top":1.25}
TextInput:
id: login
multiline:False
font_size: 28
size_hint: 0.50, 0.10
pos_hint: {"right":0.75, "top":0.70}
FloatLayout:
orientation: 'vertical'
Label:
text: 'Password'
halign: 'center'
font_size: 18
text_size: root.width-20, 20
color: 0,0,0,1
TextInput:
id: password
multiline:False
password:True
font_size: 28
size_hint: 0.50, 0.10
pos_hint: {"right":0.75, "top":0.45}
Button:
text: 'Login'
size_hint: 0.25, 0.25
font_size: 24
pos_hint: {"right":0.625, "top":0.30}
<WhiteLabel#MDLabel>
height: self.texture_size[1]
theme_text_color: "Custom"
text_color: 1, 1, 1, 1
<CustomInput#MDTextField>
multiline:False
# required: True
mode: "line"
pos_hint: {"right": 0.456}
current_hint_text_color: [0,0,0,0.5]
<RegisterScreen>:
name: "register_screen"
FloatLayout:
MDBanner:
id: banner
text: "ioshrdioaoisdhf"
MDToolbar:
id: toolbar
title: "Register"
elevation: 10
pos_hint: {'top': 1}
left_action_items: [['arrow-left', lambda screen: app.change_screen('welcome_screen', 'right')]]
BoxLayout:
orientation: "vertical"
height: self.minimum_height * 2
size_hint_y: None
pos_hint: {"top": 2}
CustomInput:
id: firstname
hint_text: "color_mode = 'custom'"
CustomInput:
id: surname
hint_text: 'Surname'
CustomInput:
id: email
hint_text: 'Email'

By naming your kv file as main.kv, you are taking advantage of the automatic loading of correctly named kv files as described in the documentation. However, you are also loading the same file using Builder.load_file("main.kv"). Loading the same kv file more than once can cause the sort of problems you are seeing. You can fix your problem by simply eliminating the call to Builder.load_file("main.kv"), or removing the entire build() method, or by changing the name of either the kv file or the MainApp class.