在tkinter中操作条目文本值

Question

我想在条目内添加单词"Search Here !"，一旦用户开始输入条目，它将消失!

就像我们在facebook网页上看到的" what 's on our mind"

from tkinter import *

class Application(Frame):
    def __init__(self, master=NONE):
        Frame.__init__(self, master)
        self.pack()
        self.create_widgets()
    def create_widgets(self):
        self.frame = Frame(self)
        self.entry = Entry(self.frame)
        self.entry.pack()
        self.frame.pack()    
if __name__ == "__main__":
    root = Tk()
    app = Application(master=root)
    app.mainloop()

Answer 1

您可以处理Entry小部件的键事件，并在第一个键事件发生时擦除内容:

from tkinter import *
class Application(Frame):
    def __init__(self, master=NONE):
        Frame.__init__(self, master)
        self.pack()
        self.create_widgets()
    def create_widgets(self):
        self.frame = Frame(self)
        self.entry = Entry(self.frame)
        self.entry.modified = False
        self.entry.insert(0, "Search Here!")
        self.entry.bind("<Key>", self.entry_key)
        self.entry.pack()
        self.frame.pack()
    def entry_key(self, event):
        if not self.entry.modified:
            self.entry.delete(0, END)
            self.entry.modified = True
if __name__ == "__main__":
    root = Tk()
    app = Application(master=root)
    app.mainloop()

为了检测第一个更改，我已经将名为modified的属性绑定并初始化到False到Entry小部件实例。当第一个键事件发生时，将删除输入框的内容，并将modified属性设置为True，从而防止在后续的键事件中清除内容。

Answer 2

你必须使用"StringVar"来设置或获取文本:

from tkinter import *

class Application(Frame):
    def __init__(self, master=NONE):
        Frame.__init__(self, master)
        self.pack()
        self.create_widgets()
    def create_widgets(self):
        self.frame = Frame(self)
        my_entry = StringVar()
        my_entry.set("Search here")
        self.entry = Entry(self.frame, text=my_entry)
        self.entry.pack()
        self.frame.pack()    
if __name__ == "__main__":
    root = Tk()
    app = Application(master=root)
    app.mainloop()