使用c＃从下拉列表中根据所选值填充列表视图 [英] populate listview based on selected value from a dropdownlist using c#

问题描述

嘿，我试图根据下拉列表中选择的值填充我的列表视图。我没有得到任何错误，但当用户选择任何下拉列表值时，不会显示列表视图。 DROPDOWNLIST1：我有一个表cat，其中包含column-id，category和categoryid ...我成功地从数据库中填充了它的值。

LISTVIEW1：基于类别ID我从下拉列表中收到我需要的更新我的列表视图

我的代码：

  protected   void  DropDownList1_SelectedIndexChanged（ object  sender，EventArgs e）
 {
 DataTable table =  new  DataTable（）; 
  //   int id = Convert.ToInt32（DropDownList1.SelectedValue）;  
  //   int id = int.Parse（DropDownList1.SelectedValue.ToString（））;  
  string  cat_id = DropDownList1.SelectedValue.ToString（）; 
  int  id; 
  if （！（ int  .TryParse（cat_id.ToString（）， out  id）））
  return ; 
 使用（SqlConnection con =  new  SqlConnection（constr））
 {
  string  sql =  选择ID，名称，描述，category，image，price，categoryid from products WHERE categoryid = @ cid ORDER BY categoryid; 
 使用（SqlCommand cmd =  new  SqlCommand（sql，con））
 { 
 使用（SqlDataAdapter da =  new  SqlDataAdapter（cmd））
 {
 cmd.Parameters.AddWithValue（  @ cid，cat_id）; 
 da.Fill（table）; 
} 
} 
 
} 
 listview.DataSource = table; 
 listview.DataBind（）; 
} 
} 

解决方案

此链接可能对您有用



http：/ /stackoverflow.com/questions/14415189/get-value-of-listview-item-on-selectedindexchanged-on-dropdownlist-in-listview [ ^ ]





http://codeblog.shawson.co.uk/quick-ref/listview-using-a-dropdownlist-populated-using-code-behind/ [ ^ ]

我是sa id较早，如果你得到了你定义的数据表的正确值，那么使用这个函数用数据表填充List视图。

  private   void  LoadList（）
 {
  //  清除ListView控件 
 listView1.Items.Clear（）; 
  int  ColCount = dtable.Columns.Count; 
  //  添加列 
  for （ int  k =  0 ; k  <  ColCount; k ++）
 {
 listView1.Columns.Add（dtable.Columns [k] .ColumnName）; 
} 
  //  在ListView控件中显示项目 
 < span class =code-keyword> for （ int  i =  0 ; i < span class =code-keyword><  dtable.Rows.Count; i ++）
 {
 DataRow drow = dtable.Rows [i]; 
 
  //  只有尚未删除的行 
 < span class =code-keyword> if （drow.RowState！= DataRowState.Deleted）
 {
  //  < span class =code-comment>定义列表项 
 ListViewItem lvi =  new  ListViewItem（drow [ 0 ]的ToString（））; 
  for （ int  j =  1 ; j <  ColCount; j ++）
 {
 lvi.SubItems.Add（drow [j] .ToString（））; 
} 
  //  将列表项添加到ListView  
 listView1.Items.Add（LVI）; 
} 
} 
} 

hey,im trying to populate my listview based on value selected in dropdownlist. actualy im not getting any errors, but listview is not displayed when user selects any dropdownlist value. DROPDOWNLIST1: i have a table say "cat" with columns-id,category and categoryid... i successfully populated its value from the database.
LISTVIEW1: based on category id i recieve from dropdownlist i need to update my listview
my code:

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        DataTable table = new DataTable();
        //int id = Convert.ToInt32(DropDownList1.SelectedValue);
        // int id = int.Parse(DropDownList1.SelectedValue.ToString());
        string cat_id = DropDownList1.SelectedValue.ToString();
        int id;
        if (!(int.TryParse(cat_id.ToString(), out id)))
            return;
        using (SqlConnection con = new SqlConnection(constr))
        {
            string sql = "select id,name,description,category,image,price,categoryid from products WHERE categoryid=@cid ORDER BY categoryid";
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                    cmd.Parameters.AddWithValue("@cid", cat_id);
                    da.Fill(table);
                }
            }

        }
        listview.DataSource = table;
        listview.DataBind();
    }
}

解决方案

this link may be useful for you

http://stackoverflow.com/questions/14415189/get-value-of-listview-item-on-selectedindexchanged-on-dropdownlist-in-listview[^]


http://codeblog.shawson.co.uk/quick-ref/listview-using-a-dropdownlist-populated-using-code-behind/[^]

As I said earlier, if you get correct value to the datatable you have defined, then use this function to populate List view using the data table.

private void LoadList()
{
// Clear the ListView control
            listView1.Items.Clear();
            int ColCount = dtable.Columns.Count;
            //Add columns
            for (int k = 0; k < ColCount; k++)
            {
               listView1.Columns.Add(dtable.Columns[k].ColumnName);
            }
            // Display items in the ListView control
            for (int i = 0; i < dtable.Rows.Count; i++)
            {
                DataRow drow = dtable.Rows[i];

                // Only row that have not been deleted
                if (drow.RowState != DataRowState.Deleted)
                {
                    // Define the list items
                    ListViewItem lvi = new ListViewItem(drow[0].ToString());
                    for (int j = 1; j < ColCount; j++)
                    {
                        lvi.SubItems.Add(drow[j].ToString());                        
                    }
                    // Add the list items to the ListView
                    listView1.Items.Add(lvi);
                }
            }
}

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