wxpython:EVT_GRID_CELL_CHANGED issue

Question

I have created a grid using wx.grid, binding with EVT_GRID_CELL_CHANGED to validate the user's input in a cell.

self.grid.Bind(wx.grid.EVT_GRID_CELL_CHANGED, self.OnCellChanged)

I try to create a wx.MessageBox to pop if the input is not int . Then I found out the messagebox will pop up twice, which is not what I want.

The handler's code is shown below:

def OnCellChanged(self, event):
    row = event.GetRow()
    col = event.GetCol()
    try:
        cell_input = int(self.grid.GetCellValue(row, col))
    except:
        self.grid.SetCellValue(row, col, '')
        msgbox = wx.MessageBox('Invalid Input! Please Try Again', 'Error', wx.OK | wx.ICON_HAND | wx.CENTRE)

Thanks for helping.

Answer 1

It seems there is some problem with MessageBox in function which handles event. But you can call it later using wx.CallAfter(function_name) or wx.CallLater(miliseconds, function_name)

def OnCellChanged(self, event):
    row = event.GetRow()
    col = event.GetCol()
    try:
        cell_input = int(self.grid.GetCellValue(row, col))

    except:            
        self.SetCellValue(row, col, '')
        #wx.CallLater(100, self.Later) # time 100ms
        wx.CallAfter(self.Later)
        print("End OnCellChange")


def Later(self):
    print("Later")
    msgbox = wx.MessageBox('Invalid Input! Please Try Again', 'Error', wx.OK | wx.ICON_HAND | wx.CENTRE)

Full working example (base on example: Mouse vs Python: wxPython - An Introduction to Grids )

import wx
import wx.grid as gridlib

class MyGrid(gridlib.Grid):

    def __init__(self, parent):
        """Constructor"""
        gridlib.Grid.__init__(self, parent)
        self.CreateGrid(12, 8)

        self.Bind(gridlib.EVT_GRID_CELL_CHANGED, self.OnCellChange)


    def OnCellChange(self, evt):
        print("OnCellChange: (%d,%d) %s\n" % (evt.GetRow(), evt.GetCol(), evt.GetPosition()))

        row = evt.GetRow()
        col = evt.GetCol()
        val = self.GetCellValue(row, col)

        try:
            cell_input = int(val)
        except:            
            self.SetCellValue(row, col, '')
            #wx.CallLater(100, self.Later) # time 100ms
            wx.CallAfter(self.Later)
            print("End OnCellChanged")


    def Later(self):
        print("Later")
        wx.MessageBox('Invalid Input! Please Try Again', 'Error', wx.OK | wx.ICON_HAND | wx.CENTRE)


class MyForm(wx.Frame):

    def __init__(self):
        """Constructor"""
        wx.Frame.__init__(self, parent=None, title="An Eventful Grid")
        panel = wx.Panel(self)

        myGrid = MyGrid(panel)

        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(myGrid, 1, wx.EXPAND)
        panel.SetSizer(sizer)

app = wx.App()
frame = MyForm().Show()
app.MainLoop()