KivyMD从textfields获取数据

Question

自从几个星期以来，我开始使用KivyMD，我爱上了这个Kivy主题。我的问题是:我正在使用KivyMD制作一个多屏幕应用程序，我的第一个屏幕是“登录屏幕”。我想在我的主类中添加一个函数，它得到我的“用户名”文本字段和我的“密码”文本字段的值。如果标识符是正确的，我需要‘屏幕2’。

这是我的代码：

from kivy.app import App
from kivy.lang import Builder
from kivy.properties import ObjectProperty
from kivy.uix.boxlayout import BoxLayout
from kivymd.theming import ThemeManager

class MyLayout(BoxLayout):

    scr_mngr = ObjectProperty(None)

    def change_screen(self, screen, *args):
        self.scr_mngr.current = screen


KV = """
#:import Toolbar kivymd.toolbar.Toolbar
#:import ThemeManager kivymd.theming.ThemeManager
#:import MDNavigationDrawer kivymd.navigationdrawer.MDNavigationDrawer
#:import NavigationLayout kivymd.navigationdrawer.NavigationLayout
#:import NavigationDrawerDivider 
kivymd.navigationdrawer.NavigationDrawerDivider
#:import NavigationDrawerToolbar 
kivymd.navigationdrawer.NavigationDrawerToolbar
#:import NavigationDrawerSubheader 
kivymd.navigationdrawer.NavigationDrawerSubheader
#:import MDCheckbox kivymd.selectioncontrols.MDCheckbox
#:import MDSwitch kivymd.selectioncontrols.MDSwitch
#:import MDList kivymd.list.MDList
#:import OneLineListItem kivymd.list.OneLineListItem
#:import TwoLineListItem kivymd.list.TwoLineListItem
#:import ThreeLineListItem kivymd.list.ThreeLineListItem
#:import OneLineAvatarListItem kivymd.list.OneLineAvatarListItem
#:import OneLineIconListItem kivymd.list.OneLineIconListItem
#:import OneLineAvatarIconListItem kivymd.list.OneLineAvatarIconListItem
#:import MDTextField kivymd.textfields.MDTextField
#:import MDSpinner kivymd.spinner.MDSpinner
#:import MDCard kivymd.card.MDCard
#:import MDSeparator kivymd.card.MDSeparator
#:import MDDropdownMenu kivymd.menu.MDDropdownMenu
#:import get_color_from_hex kivy.utils.get_color_from_hex
#:import colors kivymd.color_definitions.colors
#:import SmartTile kivymd.grid.SmartTile
#:import MDSlider kivymd.slider.MDSlider
#:import MDTabbedPanel kivymd.tabs.MDTabbedPanel
#:import MDTab kivymd.tabs.MDTab
#:import MDProgressBar kivymd.progressbar.MDProgressBar
#:import MDAccordion kivymd.accordion.MDAccordion
#:import MDAccordionItem kivymd.accordion.MDAccordionItem
#:import MDAccordionSubItem kivymd.accordion.MDAccordionSubItem
#:import MDThemePicker kivymd.theme_picker.MDThemePicker
#:import MDBottomNavigation kivymd.tabs.MDBottomNavigation
#:import MDBottomNavigationItem kivymd.tabs.MDBottomNavigationItem

#:import partial functools.partial

MyLayout:
    scr_mngr: scr_mngr
    orientation: 'vertical'

    ScreenManager:
        id: scr_mngr
        Screen:
            name: 'screen1'
            MDCard:
                size_hint: None, None
                size: dp(520), dp(340)
                pos_hint: {'center_x': 0.5, 'center_y': 0.5}
                BoxLayout:
                    orientation:'vertical'
                    padding: dp(20)
                    spacing:20
                    MDLabel:
                        text: 'Connexion'
                        theme_text_color: 'Secondary'
                        font_style:"Title"
                        size_hint_y: None
                        height: dp(36)
                    MDSeparator:
                        height: dp(1)
                    MDTextField:
                        id: 'username'
                        hint_text: "Username "
                        helper_text_mode: "on_focus"
                    MDTextField:
                        id: 'password'
                        hint_text: "Password "
                        helper_text_mode: "on_focus"

                    MDFlatButton:
                        text: "Connexion"
                        pos_hint: {'center_x': 0.5}
                        on_release: root.check_data_login()
        Screen:
            name: 'screen2'
            Toolbar:
                id: toolbar
                title: "Welcome ! "
                pos_hint: {'center_x': 0.5, 'center_y': 0.97}
                md_bg_color: app.theme_cls.primary_color
                background_palette: 'DeepPurple'
                background_hue: 'A400'
                left_action_items: [['arrow-left', p 
                    partial(root.change_screen, 'screen1') ]]
                right_action_items: [['animation', lambda x: M 
                    MDThemePicker().open()]]

            MDLabel:
                font_style: 'Title'
                theme_text_color: 'Primary'
                text: "Data :"
                height: self.texture_size[1] + dp(3)
                halign: 'center'
                pos_hint: {'center_x': 0.5, 'center_y': 0.85}




"""


class MyApp(App):
    theme_cls = ThemeManager()

    def build(self):
        return Builder.load_string(KV)


    def check_data_login(self):
        username = self.username.text
        password= self.password.text

        print(username)
        print(password)

MyApp().run()

Answer 1

解决方案

解决方案是使用Kivy ObjectProperty连接到ids。详情请参阅示例。

kv文件

添加以下id和ObjectProperties

1. 添加id: screen1
2. 添加ObjectProperty，screen1: screen1
3. id不是字符串。从id: username和id: password中删除引号
4. 添加ObjectProperty，username: username
5. 添加ObjectProperty，password: password
6. 将password: True添加到TextInput，以便隐藏密码

片段- kv文件

ScreenManager:
    id: scr_mngr
    screen1: screen1

    Screen:
        id: screen1
        name: 'screen1'
        username: username
        password: password

        MDCard:
            ...
                MDTextField:
                    id: username
                    hint_text: "Username "
                    helper_text_mode: "on_focus"

                MDTextField:
                    id: password
                    hint_text: "Password "
                    helper_text_mode: "on_focus"
                    password: True

Python文件

1. 将check_data_login()方法从class MyApp()移动到class MyLayout()
2. 将self.username.text替换为self.scr_mngr.screen1.username.text
3. 将self.password.text替换为self.scr_mngr.screen1.password.text
4. 添加了if语句以检查用户名和密码

代码片段- Python文件

class MyLayout(BoxLayout):

    scr_mngr = ObjectProperty(None)

    def check_data_login(self):
        username = self.scr_mngr.screen1.username.text
        password = self.scr_mngr.screen1.password.text

        print(username)
        print(password)

        if username == "KivyMD" and password == "kivy":
            self.change_screen("screen2")

Kivy文档

kv文件的语法

如果小部件没有具有给定名称的属性，则将自动创建ObjectProperty并将其添加到小部件中。

引用小部件ids

警告 当将值赋值给id时，请记住该值不是字符串。没有引号:好的-> id: value，坏的-> id：'value‘

在python代码中访问Kv中定义的小部件

使用ObjectProperty通常被认为是“最佳实践”。这将创建一个直接引用，提供更快的访问速度，并且更加显式。

示例

main.py

from kivy.app import App
from kivy.lang import Builder
from kivy.properties import ObjectProperty
from kivy.uix.boxlayout import BoxLayout
from kivymd.theming import ThemeManager


class MyLayout(BoxLayout):

    scr_mngr = ObjectProperty(None)

    def check_data_login(self):
        username = self.scr_mngr.screen1.username.text
        password = self.scr_mngr.screen1.password.text

        print(username)
        print(password)

        if username == "KivyMD" and password == "kivy":
            self.change_screen("screen2")

    def change_screen(self, screen, *args):
        self.scr_mngr.current = screen


KV = """
#:import Toolbar kivymd.toolbar.Toolbar
#:import ThemeManager kivymd.theming.ThemeManager
#:import MDNavigationDrawer kivymd.navigationdrawer.MDNavigationDrawer
#:import NavigationLayout kivymd.navigationdrawer.NavigationLayout
#:import NavigationDrawerDivider kivymd.navigationdrawer.NavigationDrawerDivider
#:import NavigationDrawerToolbar kivymd.navigationdrawer.NavigationDrawerToolbar
#:import NavigationDrawerSubheader kivymd.navigationdrawer.NavigationDrawerSubheader
#:import MDCheckbox kivymd.selectioncontrols.MDCheckbox
#:import MDSwitch kivymd.selectioncontrols.MDSwitch
#:import MDList kivymd.list.MDList
#:import OneLineListItem kivymd.list.OneLineListItem
#:import TwoLineListItem kivymd.list.TwoLineListItem
#:import ThreeLineListItem kivymd.list.ThreeLineListItem
#:import OneLineAvatarListItem kivymd.list.OneLineAvatarListItem
#:import OneLineIconListItem kivymd.list.OneLineIconListItem
#:import OneLineAvatarIconListItem kivymd.list.OneLineAvatarIconListItem
#:import MDTextField kivymd.textfields.MDTextField
#:import MDSpinner kivymd.spinner.MDSpinner
#:import MDCard kivymd.card.MDCard
#:import MDSeparator kivymd.card.MDSeparator
#:import MDDropdownMenu kivymd.menu.MDDropdownMenu
#:import get_color_from_hex kivy.utils.get_color_from_hex
#:import colors kivymd.color_definitions.colors
#:import SmartTile kivymd.grid.SmartTile
#:import MDSlider kivymd.slider.MDSlider
#:import MDTabbedPanel kivymd.tabs.MDTabbedPanel
#:import MDTab kivymd.tabs.MDTab
#:import MDProgressBar kivymd.progressbar.MDProgressBar
#:import MDAccordion kivymd.accordion.MDAccordion
#:import MDAccordionItem kivymd.accordion.MDAccordionItem
#:import MDAccordionSubItem kivymd.accordion.MDAccordionSubItem
#:import MDThemePicker kivymd.theme_picker.MDThemePicker
#:import MDBottomNavigation kivymd.tabs.MDBottomNavigation
#:import MDBottomNavigationItem kivymd.tabs.MDBottomNavigationItem

#:import partial functools.partial

MyLayout:
    scr_mngr: scr_mngr
    orientation: 'vertical'

    ScreenManager:
        id: scr_mngr
        screen1: screen1

        Screen:
            id: screen1
            name: 'screen1'
            username: username
            password: password

            MDCard:
                size_hint: None, None
                size: dp(520), dp(340)
                pos_hint: {'center_x': 0.5, 'center_y': 0.5}

                BoxLayout:
                    orientation:'vertical'
                    padding: dp(20)
                    spacing:20

                    MDLabel:
                        text: 'Connexion'
                        theme_text_color: 'Secondary'
                        font_style:"Title"
                        size_hint_y: None
                        height: dp(36)

                    MDSeparator:
                        height: dp(1)

                    MDTextField:
                        id: username
                        hint_text: "Username "
                        helper_text_mode: "on_focus"

                    MDTextField:
                        id: password
                        hint_text: "Password "
                        helper_text_mode: "on_focus"
                        password: True

                    MDFlatButton:
                        text: "Connexion"
                        pos_hint: {'center_x': 0.5}
                        on_release: root.check_data_login()
        Screen:
            name: 'screen2'

            Toolbar:
                id: toolbar
                title: "Welcome ! "
                pos_hint: {'center_x': 0.5, 'center_y': 0.97}
                md_bg_color: app.theme_cls.primary_color
                background_palette: 'DeepPurple'
                background_hue: 'A400'
                left_action_items: [['arrow-left', partial(root.change_screen, 'screen1') ]]
                right_action_items: [['animation', lambda x: MDThemePicker().open()]]

            MDLabel:
                font_style: 'Title'
                theme_text_color: 'Primary'
                text: "Data :"
                height: self.texture_size[1] + dp(3)
                halign: 'center'
                pos_hint: {'center_x': 0.5, 'center_y': 0.85}
"""


class MyApp(App):
    title = "Kivy MD Demo"
    theme_cls = ThemeManager()

    def build(self):
        return Builder.load_string(KV)


MyApp().run()

输出

​

​

Answer 2

另一种有按钮的方法。你的kv档案：

KV = """
Screen:
    
    
    MDLabel:
        id: direct
        text: 'Paste File Path: '
        color: [0.6,0.5,0.3,1,1]
                
        pos_hint: {"center_x": .55, "center_y": .7}

    MDTextField:
        id: getpath
        hint_text: "Include file name with its extension"
        pos_hint: {"center_x": .5, "center_y": 0.7}
        size_hint_x: None
        width: "300dp"

    MDRaisedButton:
        text: "Check Text"
        color: "green"
        pos_hint: {"center_x": .5, "center_y": .45}
        on_release: app.checkprint()

"""

以及您的主要python脚本：

class OneApp(MDApp):

    def build(self):
        self.theme_cls.primary_palette = 'Green'
        self.screen = Builder.load_string(KV)
    

        return self.screen

    
    def checkprint(self):
        value = self.screen.ids.getpath.text
        print("What you typed is: ", value)

OneApp().run()