如何在c＃中验证组合框，组合框使用数据源 [英] how can validate combobox in c#, combobox used datasource

问题描述

我有3个组合框





每个组合框数据从另一个组合框源绑定



例如。



学生类型= dayscholar

宿舍

---



如果我选择dayscholar另一个组合框显示学生姓名



如果我选择学生姓名，第三个组合框显示学生分数



问题是



如何验证组合框（选择与否）



i尝试选择索引，选择文字，文字但不使用

I have 3 comboboxes


each combobox data binds from another combobox source

for eg.

student type = dayscholar
hostel
---

if i select dayscholar the another combobox shows student name

if i select student name, the third combobox shows student marks

problem is

how to validate combobox (select or not)

i tried selectedindex, selecteditem, text but no use

private void cmbtype_SelectedIndexChanged(object sender, EventArgs e)
      {
          if (cmbtype.Text == string.Empty)
              return;

//bind name combobox1
         OleDbdatadapter da = new OleDbdatadapter("select name,id from member_master where Subscribe_Type='" + cmbtype.Text.Trim() + "'  order by name", con);

ds = new DataSet();
da.Fill(ds);
cmbname.Items.Insert(0, string.Empty);
cmbname.DataSource = ds.Tables[0];
cmbname.DisplayMember = "name";
cmbname.ValueMember = "id";

}

private void cmbname_SelectedIndexChanged(object sender, EventArgs e)
{
    if (cmbname.SelectedIndex <= 0)
        return;
    gen_table();
}

private void cmbfor_SelectedIndexChanged(object sender, EventArgs e)
{
    if (cmbfor.Text != "")
        gen_table();
}
private void gen_table()
{
    if (cmbtype.SelectedItem == null)
        return;
    //if (comboBox1.SelectedItem     == null)
    //    return;
    //if (comboBox1.SelectedValue  == null)
    //    return;
    //if (comboBox1.Text  == null)
    //    return;
    if (cmbname.SelectedIndex == 0)
        return;

}

}

}
}

推荐答案

试试这个。



请记得给我的答案评分。





///检查组合框是否合适t被选中



if（！string.IsNullOrWhiteSpace（cmbtype.Text））



{



{

try this.

Please remember to rate my answer.


/// Check If combobox text is selected

if (!string.IsNullOrWhiteSpace(cmbtype.Text))

{

{

private void cmbtype_SelectedIndexChanged(object sender, EventArgs e)
        {
              //bind name combobox1
            OleDbDataAdapter da = new OleDbDataAdapter("select name,id from member_master where Subscribe_Type='" + cmbtype.Text.Trim() + "'  order by name", con);
            ds = new DataSet();
            da.Fill(ds);
            cmbname.Items.Insert(0, string.Empty);
            cmbname.DataSource = ds.Tables[0];
            cmbname.DisplayMember = "name";
            cmbname.ValueMember = "id";
            cmbname.SelectedIndex = -1;
}

   private void cmbname_SelectedIndexChanged(object sender, EventArgs e)
        {


            /// Check If combobox text is selected

            if (!string.IsNullOrWhiteSpace(cmbname.Text))
{   /////
            return;
            gen_table();
        
}  /////

your code should be inbetween the brackets.

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