what does it mean by 'MyApp' has no attribute 'label_text'? where do i add label-CodePudding

im trying to program my project so that when I click the button "click it" the text "never gonna give you up" in the title is replaced with whatever text is in the text box. here's most of my code:

class MyApp:
    
    def __init__(self, root):
        root.title("never gonna give you up") #title of the window
        root.geometry("1000x500") #the size of the window on launch
        root.maxsize(2000,1000) #the maximum size of the window
            
        label=Label(root,text='the text thats displayed in the window',bg="red") #creates a 'label' for the window 'root'
        label.pack() #displays widget
            
            #using dictionary syntax, one at a time
            #label['text']="new label text"
            #label["font"]=("Arial",30)
            
           
           #using configure method
        label.configure(text="never gonna give you up", font=("Comic Sans MS", 20))
                            
        self.entry_text=StringVar() #used to hold text in entry, can be bound to other widgets
        entry=Entry(root, textvariable=self.entry_text) #when this changes stingvar will change as well
        entry.pack() #will display widget below other widget
                            
            #label["textvariable"]=entry_text #binds label to what is typed in entry
        button=Button(root, text="click it",command=self.press_button)
        button.pack()
            
            #label.configure(text="new xxx", font=("Comic Sans MS",26))
    def press_button(self):
        text=self.entry_text.get()
        self.label_text.set(text)

whenever I click the button, it returns this error:

line 34, in press_button
    self.label_text.set()
AttributeError: 'MyApp' object has no attribute 'label_text'

I've been working on this for a couple days, and I still don't know whats wrong.

CodePudding user response：

self.label_testis not defined anywhere in the class. That is why you are getting AttributeError. I guess you want to change the window title too. Also, if you want to modify the label outside __init__() you need to make the variable accessible globally throughout the class by using self.label = Label() instead of just label = Label() in __init__(). The code below incorporates the required modifications, while also changing the window title.

class MyApp:

    def __init__(self, root):
        self.root = root #so that root remains accessible everywhere in MyApp and not just here
        root.title("never gonna give you up") #title of the window
        root.geometry("1000x500") #the size of the window on launch
        root.maxsize(2000,1000) #the maximum size of the window
        
        #use self.label instead of label so that it's accessible in press_button()
        self.label=Label(root,text='the text thats displayed in the window',bg="red") #creates a 'label' for the window 'root'
        self.label.pack() #displays widget
        
        #using dictionary syntax, one at a time
        #label['text']="new label text"
        #label["font"]=("Arial",30)
        
       
        #using configure method
        self.label.configure(text="never gonna give you up", font=("Comic Sans MS", 20))
                        
        self.entry_text=StringVar() #used to hold text in entry, can be bound to other widgets
        entry=Entry(root, textvariable=self.entry_text) #when this changes stingvar will change as well
        entry.pack() #will display widget below other widget
                        
        #label["textvariable"]=entry_text #binds label to what is typed in entry
        button=Button(root, text="click it",command=self.press_button)
        button.pack()
        
        #label.configure(text="new xxx", font=("Comic Sans MS",26))
 
   def press_button(self):
        text=self.entry_text.get()
        #self.label_text.set(text) #Will give error as self.label_text isn't defined anywhere in MyApp
        self.label.configure(text=text, font=("Comic Sans MS", 20))
        self.root.title(text) #will change the window title too

CodePudding user response：

You can use:

class MyApp:

def __init__(self, root):
    root.title("never gonna give you up") #title of the window
    root.geometry("1000x500") #the size of the window on launch
    root.maxsize(2000,1000) #the maximum size of the window
        
    label=Label(root,text='the text thats displayed in the window',bg="red") #creates a 'label' for the window 'root'
    label.pack() #displays widget
        
        #using dictionary syntax, one at a time
        #label['text']="new label text"
        #label["font"]=("Arial",30)
        
       
       #using configure method
    label.configure(text="never gonna give you up", font=("Comic Sans MS", 20))
                        
    self.entry_text=StringVar() #used to hold text in entry, can be bound to other widgets
    entry=Entry(root, textvariable=self.entry_text) #when this changes stingvar will change as well
    entry.pack() #will display widget below other widget
                        
        #label["textvariable"]=entry_text #binds label to what is typed in entry
    button=Button(root, text="click it",command=self.press_button)
    button.pack()
        
        #label.configure(text="new xxx", font=("Comic Sans MS",26))
def press_button(self):
    text=self.entry_text.get()
    self.label["text"] = text

Your code uses label_text, but it isn't defined. Normal name is label. And method "set" is not defined on tkinter.Label.