vs2005 combox(winform) 绑定数据时触发SelectedIndexChanged的问题

今天遇到一个不小问题,vs2005里面自带的combox(winform)的问题.

问题：我将webservice发布的方法返回的数据集绑定到combox的dataSouce.然后设置这个combox的displaymenber和valuemenber.

步骤是这样：

１datatable->datasource

2.set datatalbe.字段１->displaymenber

３set datatalbe.字段２->valuemenber

这样没有问题.

但当我在combox的SelectedIndexChanged事件中写了获取当前combox的已选择的类的编号属性的时候,发现总在报错.

数据项索引小于无穷大。

经调试发现:

程序执行到步骤１时没有继续执行步骤２，而是转向触发combox的SelectedIndexChanged事件。这时的combox没有绑定完数据，自然会报错了。

解决

设置一个bool类型,标志符IsBinded,在填充方法完毕后,设为true.允许SelectedIndexChanged被触发.

代码如下:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using SupplyProduct.WebReference;

namespace SupplyProduct
...{
    public partial class Form1 : Form
    ...{
        private int _cityID=-1;
        private bool _isBinded = false;
        public int CityID
        ...{
            get
            ...{
                if (_cityID < 0)
                    return 0;
                return _cityID;
            }
            set
            ...{
                _cityID = value;
            }
        }
        public bool IsBinded
        ...{
            get
            ...{
                return _isBinded;
            }
            set
            ...{
                _isBinded = value;
            }
        }
        public Form1()
        ...{
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        ...{
            CityID = 0;
            BindCities(ref cbProvince);
            CityID = (int)cbProvince.SelectedValue;
            BindCities(ref cbCity);
        }
        private void BindCities(ref ComboBox combox)
        ...{
            WSCitiesBLL cityAPI = new WSCitiesBLL();
            chemchina.CitiesDataTable cities = cityAPI.GetChildCties(CityID);
            combox.DataSource = cities;
            combox.DisplayMember = "cityName";
            combox.ValueMember = "cityID";
            IsBinded = true;
        }

        private void cbProvince_SelectedIndexChanged(object sender, EventArgs e)
        ...{
            if (IsBinded&&cbProvince.SelectedValue!=null)
            ...{
                CityID = (int)cbProvince.SelectedValue;
                BindCities(ref cbCity);
            }
        }
    }
}