将一般的 ASP.NET 控件视为基于列表的控件（即 DropDownList、RadioButtonList 等）

Question

I have built a method that clears and resets a DropDownList with the appropriate data as specified by the user, like so:

protected void ResetDDL(DropDownList ddl, DataTable dt)
{
    ddl.Items.Clear();
    ddl.DataSource = dt;
    ddl.DataBind();
}
private void LoadVehicleTypes()
{
    DataTable dt = new DataTable();
    SqlConnection sc = new SqlConnection(ConfigurationManager.ConnectionStrings["sqlconnectionstring"].ConnectionString);
    sc.Open();
    SqlDataAdapter sda = new SqlDataAdapter("procedure", sc);
    sda.SelectCommand.CommandType = CommandType.StoredProcedure;
    sda.Fill(dt);
    sc.Close();

    ResetDDL(ddlYourDropDown, dt);
}

While this works as well as it should, I noticed that the code to do the same for a RadioButtonList is identical and it made me wonder if there's a way to combine ResetDDL with the RadioButtonList equivalent: ResetRBL. To do this, I tried replacing DropDownList in the code with Control , but this only yielded in a Control does not contain a definition for 'Items/DataSource' error, so I looked to see if there was any way to tell the program that a given Control is a DropDownList or RadioButtonList and what to do with them once they are confirmed to be a DDL or RBL. The idea here is to take the name of one of these controls, find the actual control itself, and execute the reset method.

From here, I ran a test to see if I could get the Control's type -- and I could!

bool itworks = false;
string tst = rbl.GetType().ToString(); // in this case, tst is "System.Web.UI.WebControls.DropDownList"
if (tst.Contains("RadioButtonList"))
    itworks = true;

From here I thought getting the control type would be as simple as getting the text out of a Control in a GridView, but this was not the case. I realized that whereas you can easily fetch the GridView's text and put it into a procedure --

foreach (GridViewRow row in gvTempVehicleData.Rows)
{
    SqlCommand cmdVData = new SqlCommand("cmdVDataProcedure", sc);
    cmdVData.CommandType = CommandType.StoredProcedure;
    cmdVData.Parameters.AddWithValue("DataYear", ((TextBox)row.FindControl("txtTempDataYear")).Text);
    cmdVData.ExecuteNonQuery();
}

-- it doesn't seem like quite the same can be done for a vehicle outside a GridView. But still I'm wondering: is there a way to take a Control's name as a string, find the actual control of the same name, and use the methods of the control type I'm looking for? If this is possible, I think it could help a bit to chop down the amount of code at my disposal.

Any help at all would be greatly appreciated!

Answer 1

The problem is that the type of control being taken in. Rather than a Control , the method should accept a ListControl like so:

public void ResetList(ListControl control, DataTable newData)
{
    control.Items.Clear();
    control.DataSource = newData;
    control.DataBind();
}