在 tkinter 中交互式验证 Entry 小部件内容（第 2 部分 - 更改 entry 对象的属性）

Question

我正在尝试使用此处答案中的验证程序：Interactively validating Entry widget content in tkinter

我想通过检查输入类型来更改背景颜色。不幸的是，我无法将入口指针传递给验证函数：vcmd = (self.register(self.onValidate), '%d', '%i', '%P', '%s', '%S', '%v', '%V', '%W')。因此，我尝试了这个：

    self.entry = tk.Entry(self, validate="all")
    self.entry['validatecommand'] = self.onValidate2(self.entry)

但这只有效一次。您能否解释一下访问调用验证函数（或其他函数）的对象的最佳方法是什么，以及为什么我的 validatecommand 用法只能使用一次？

这是上面 link 的完整代码，并进行了一些更正：

import tkinter as tk  # python 3.x
# import Tkinter as tk # python 2.x

class Example(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)

        # valid percent substitutions (from the Tk entry man page)
        # note: you only have to register the ones you need; this
        # example registers them all for illustrative purposes
        #
        # %d = Type of action (1=insert, 0=delete, -1 for others)
        # %i = index of char string to be inserted/deleted, or -1
        # %P = value of the entry if the edit is allowed
        # %s = value of entry prior to editing
        # %S = the text string being inserted or deleted, if any
        # %v = the type of validation that is currently set
        # %V = the type of validation that triggered the callback
        #      (key, focusin, focusout, forced)
        # %W = the tk name of the widget

        vcmd = (self.register(self.onValidate),
                '%d', '%i', '%P', '%s', '%S', '%v', '%V', '%W')
 #       self.entry = tk.Entry(self, validate="key", validatecommand=vcmd)
        self.entry = tk.Entry(self, validate="all")
#        self.entry['validatecommand'] = vcmd
        self.entry['validatecommand'] = self.onValidate2(self.entry)
        self.text = tk.Text(self, height=10, width=40)
        self.entry.pack(side="top", fill="x")
        self.text.pack(side="bottom", fill="both", expand=True)

def onValidate(self, d, i, P, s, S, v, V, W):
        self.text.delete("1.0", "end")
        self.text.insert("end","OnValidate:\n")
        self.text.insert("end","d='%s'\n" % d)
        self.text.insert("end","i='%s'\n" % i)
        self.text.insert("end","P='%s'\n" % P)
        self.text.insert("end","s='%s'\n" % s)
        self.text.insert("end","S='%s'\n" % S)
        self.text.insert("end","v='%s'\n" % v)
        self.text.insert("end","V='%s'\n" % V)
        self.text.insert("end","W='%s'\n" % W)
        self.text.insert("end","W='%s'\n" % W)
        W.config({"background": "Red"})

        # Disallow anything but lowercase letters
        if S == S.lower():
            return True
        else:
            self.bell()
            return False


    def onValidate2(self, entry):
        try:
            entry.config({"background": "White"})
            value = int(entry.get())
            print("Int Value=",value)
#                return int(value)
        except ValueError:
            entry.config({"background": "Red"})

if __name__ == "__main__":
    root = tk.Tk()
    Example(root).pack(fill="both", expand=True)
    root.mainloop()

Answer 1

I can't pass the entry pointer to the validation function

您可以传递入口小部件的名称，并使用 tkinter 的 nametowidget 方法将该名称转换为小部件的实例。

Could you please explain ... why my validatecommand usage only works once?

您没有正确配置验证命令。考虑这段代码：

self.entry['validatecommand'] = self.onValidate2(self.entry)

以上代码在功能上与此相同：

result = self.onValidate2(self.entry)
self.entry['validatecommand'] = result

换句话说，您立即调用验证函数，然后将 validatecommand 选项设置为 None。 validationcommand 选项必须设置为 callable。

这是您要实现的目标的工作示例。通常 validate 命令必须 return True 有效条目和 False 无效条目，但我猜你实际上想要允许无效条目而只是想打开背景红色.

此示例创建了多个条目小部件，因此您可以看到通过将小部件的名称传递给验证函数，单个验证函数适用于多个小部件。

import tkinter as tk

class Example(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)

        vcmd = self.register(self.onValidate)

        for i in range(4):
            entry = tk.Entry(self, validate="all")
            entry.configure(validatecommand=(vcmd, "%W", "%P"))
            entry.pack(side="top", fill="x")

    def onValidate(self, entry_name, new_value):
        entry = self.nametowidget(entry_name)
        entry.configure(background="white")
        try:
            int(new_value)
        except ValueError:
            entry.configure(background="red")
        return True

if __name__ == "__main__":
    root = tk.Tk()
    Example(root).pack(fill="both", expand=True)
    root.mainloop()

在 tkinter 中交互式验证 Entry 小部件内容（第 2 部分 - 更改 entry 对象的属性）

Interactively validating Entry widget content in tkinter (part 2 - change the properties of the entry object)

python

validation

tkinter

tkinter-entry