如何在按下按鈕後動態更新Kivy標籤

我試圖製作一個使用MySQL服務器數據的應用程序。到目前爲止，我一直很好，直到我偶然發現需要更新標籤。如何在按下按鈕後動態更新Kivy標籤

這是我到目前爲止有：

from kivy.uix.button import Button 
from kivy.lang import Builder 
from kivy.uix.screenmanager import ScreenManager, Screen 
from kivy.uix.label import Label 
from kivy.uix.scrollview import ScrollView 
from kivy.clock import Clock 
import MySQLdb 
class MainView(ScrollView): 

    def qchange(self): 
     query = 'SELECT * FROM `citiestovisit` ORDER BY `idcitiestovisit`' 
     self.db_data(query) 
    q = 'SELECT * FROM `citiestovisit` ORDER BY `Name`' 
    def db_data(self, query=q): 
     #vector = ListProperty() 
     vector = [] 
     con = MySQLdb.connect(host="localhost", user="root", passwd="", db="cities") 
     cur = con.cursor() 
     cur.execute('SET NAMES `utf8`') 
     cur.execute(query) 
     result = cur.fetchall() 
     for row in result: 
      string = str(row[0]) + " " + str(row[1]) + " " + str(row[2]) 
      vector.append(string) 
     print vector 
     return vector 
    def __init__(self, **kwargs): 
     kwargs['cols'] = 2 
     super(MainView, self).__init__(**kwargs) 
     GL = GridLayout(cols = 3, spacing=10, size_hint_y=None) 
     GL.bind(minimum_height=GL.setter('height')) 
     for row in self.db_data(): 
      splitRow = row.split(" ") 
      for data in splitRow: 
       GL.add_widget(Label(text=data,size_hint_y=None, font_size='20sp')) 
     self.add_widget(GL) 
Builder.load_string(""" 
<MenuScreen>: 
    BoxLayout: 
     GridLayout: 
      cols: 1 
      Button: 
       text: 'Goto settings' 
       on_press: 
        root.manager.transition.direction = 'left' 
        root.manager.current = 'settings' 
      Button: 
       text: 'Quit' 
     Label: 
      font_name: 'C:\Anonymous\Anonymous.ttf' 
      text: "picture here" 

<SettingsScreen>: 
""") 

# Declare both screens 
class MenuScreen(Screen): 
    pass 

class SettingsScreen(Screen): 
    pass 

ss = SettingsScreen(name='settings') 
layout = BoxLayout(orientation='vertical') 
BL = BoxLayout() 
layout.add_widget(BL) 

#Instance of a MainView class 

MV = MainView() 

def callback(instance): 
    sm.transition.direction = 'right' 
    sm.current = 'menu' 
def callback2(instance): 
    MV.qchange() 



btn = Button(text="Back to Menu") 
btn.bind(on_press=callback) 
btn.size_hint = (1, 0.3) 
BL.add_widget(btn) 

btn2 = Button(text="Sort by ID") 
btn2.size_hint = (1, 0.3) 
btn2.bind(on_press=callback2) 
BL.add_widget(btn2) 

layout.add_widget(MainView()) 

sublayout = GridLayout(cols=3) 
sublayout.add_widget(Label(text="hello")) 
sublayout.add_widget(Label(text="World")) 
sublayout.add_widget(Label(text="Python")) 
layout.add_widget(sublayout) 

ss.add_widget(layout) 

# Create the screen manager 
sm = ScreenManager() 
sm.add_widget(MenuScreen(name='menu')) 
sm.add_widget(ss) 

class MyApp(App): 
    def build(self): 
     return sm 

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

我在def qchange(self) mehod，因爲它傳遞到def db_data(self, query=q)一個新的查詢特別感興趣;因此請求被髮送到數據庫並返回一個字符串數組。但是，此數組不會被更進一步處理，並且GL小部件中的標籤不會更新。我想我需要添加在MainView中調用__init__的時鐘，但這只是一個猜測，因爲我也讀過關於使用屬性的內容（我不知道如何在此處使用它）

I'我編了我的代碼。現在，它看起來像這樣：

class MainView(ScrollView): 

    def qchange(self): 

     query = 'SELECT * FROM `citiestovisit` ORDER BY `idcitiestovisit`' 
     #self.db_data(query) 
     #LG = self.LabelsGrid(self.GL) 

    q = 'SELECT * FROM `citiestovisit` ORDER BY `Name`' 

    def db_data(self, query=q): 

     vector = [] 

     con = MySQLdb.connect(host="localhost", user="root", passwd="", db="cities") 
     cur = con.cursor() 
     cur.execute('SET NAMES `utf8`') 
     cur.execute(query) 

     result = cur.fetchall() 

     for row in result: 
      string = str(row[0]) + " " + str(row[1]) + " " + str(row[2]) 

      vector.append(string) 

     print vector 
     return vector 

    class LabelsGrid(GridLayout): 
     def __init__(self, **kwargs): 
      self.cols = 3 
      self.spacing = 10 
      self.size_hint_y = None 

     def show_labels(self, strings): 
      self.clear_widgets() 

      for row in strings: 
       splitRow = row.split(" ") 
       for data in splitRow: 
        label = Label(text=data, size_hint_y=None, font_size='20sp') 
        self.add_widget(label) 



    GL = LabelsGrid() 
    def __init__(self, **kwargs): 
     kwargs['cols'] = 2 
     super(MainView, self).__init__(**kwargs) 
     self.GL=self.LabelsGrid() 
     # GL = GridLayout(cols = 3, spacing=10, size_hint_y=None) 
     self.GL.bind(minimum_height=self.GL.setter('height')) 

     self.GL.show_labels(self.db_data(self.q)) 

     self.add_widget(self.GL) 

     #self.GL.clear_widgets() 

Builder.load_string(""" 

<MenuScreen>: 
    BoxLayout: 
     GridLayout: 
      cols: 1 
      Button: 
       text: 'Goto settings' 
       on_press: 
        root.manager.transition.direction = 'left' 
        root.manager.current = 'settings' 
      Button: 
       text: 'Quit' 
     Label: 
      font_name: 'C:\Anonymous\Anonymous.ttf' 
      text: "picture here" 

<SettingsScreen>: 


""") 

# Declare both screens 
class MenuScreen(Screen): 
    pass 

class SettingsScreen(Screen): 
    pass 

ss = SettingsScreen(name='settings') 
layout = BoxLayout(orientation='vertical') 
BL = BoxLayout() 
layout.add_widget(BL) 

#Instance of a MainView class 

MV = MainView() 

def callback(instance): 
    sm.transition.direction = 'right' 
    sm.current = 'menu' 
def callback2(instance): 
    MV.qchange() 



btn = Button(text="Back to Menu") 
btn.bind(on_press=callback) 
btn.size_hint = (1, 0.3) 
BL.add_widget(btn) 

btn2 = Button(text="Sort by ID") 
btn2.size_hint = (1, 0.3) 
btn2.bind(on_press=callback2) 
BL.add_widget(btn2) 

layout.add_widget(MainView()) 

sublayout = GridLayout(cols=3) 
sublayout.add_widget(Label(text="hello")) 
sublayout.add_widget(Label(text="World")) 
sublayout.add_widget(Label(text="Python")) 
layout.add_widget(sublayout) 

ss.add_widget(layout) 

# Create the screen manager 
sm = ScreenManager() 
sm.add_widget(MenuScreen(name='menu')) 
sm.add_widget(ss) 

class MyApp(App): 
    def build(self): 
     return sm 

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

通過添加

class LabelsGrid(GridLayout): 
      def __init__(self, **kwargs): 
       self.cols = 3 
       self.spacing = 10 
       self.size_hint_y = None 

      def show_labels(self, strings): 
       self.clear_widgets() 

       for row in strings: 
        splitRow = row.split(" ") 
        for data in splitRow: 
         label = Label(text=data, size_hint_y=None, font_size='20sp') 
         self.add_widget(label)

我想根據給定的建議添加自定義網格佈局，不過，現在我得到一個錯誤說：

AttributeError: 'LabelsGrid' object has no attribute '_trigger_layout'

關於如何處理這個問題的任何想法？

來源

2016-05-12 Ivan Prizov

創建自定義網格佈局，比如LabelsGrid，並在該類中實現一個方法show_labels。例如：

class LabelsGrid(GridLayout): 

    def show_labels(self, strings): 
     self.clear_widgets() 

     for text in strings: 
      label = Label(text=text) 
      self.add_widget(label)

這樣，每次調用列表中標籤名稱的方法時，它都會自行更新。

來源

2016-05-12 09:17:27 jligeza

請問，你可以解釋一下，因爲我已經在__init__方法中有一個GridLayout小部件。根據你的建議，我應該添加這個類到MainView類，不是嗎？我應該如何處理已經是GridLayout的GL小部件？ –

@JohnAward用這個自定義網格佈局替換舊的網格佈局。 – jligeza

如何在按下按鈕後動態更新Kivy標籤

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