将日期绑定到GridView中的下拉列表

Question

I have to bind a label and a drop down in a gridview,the DDL contains rundates that is datetime format i have to show all the different dates in the DDL associated with the name.

  protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DataTable dt = new DataTable();
        dt = Common.rundate();
        DropDownList ddl = e.Row.FindControl("DropDownList1") as DropDownList;

        ddl.DataTextField = "RunDate";
        ddl.DataValueField = "TempID";
        ddl.DataSource = dt;
        ddl.DataBind();
    }

}

Store Proc::  

    alter PROC display_rundates
@rundate datetime,@tempid int
AS
  SELECT RunDate,TempID
    FROM History_Table

ORDER BY Rundate DESC
GO

But i have to show the specific rundates associated with each Name.Any help can be appreciated.

Name   rundate
Test   datetime(DDL)
Test1   datetime

Answer 1

Try this

ddl.SelectedValue = ((System.Data.DataRowView)(e.Row.DataItem)).Row["TempId"].ToString();

Basically just get "TempId" from the data item during GridView1_RowDataBound and assign that "TempId" to drop down's Selected value.

Something like this

void bindGrid()
{
   grid.DataSource = getRunDates();
   grid.DataBind();
}
DataTable getRunDates()
{
   DataTable dt = new DataTable();
   dt.Columns.Add("TempID");
   dt.Columns.Add("RunDate");
   dt.Rows.Add(new object[] { 1, "20-May-2012" });
   dt.Rows.Add(new object[] { 2, "21-May-2012" });
   dt.Rows.Add(new object[] { 3, "10-May-2012" });
   dt.Rows.Add(new object[] { 4, "20-May-2012" });
   return dt;
}
protected void grid_RowDataBound(object sender, GridViewRowEventArgs e)
{
   if (e.Row.RowType == DataControlRowType.DataRow)
   {
      DataTable dt = new DataTable();
      dt = getRunDates();
      DropDownList ddl = e.Row.FindControl("DropDownList1") as DropDownList;

      ddl.DataTextField = "RunDate";
      ddl.DataValueField = "TempID";
      ddl.DataSource = dt;
      ddl.DataBind();

      ddl.SelectedValue = ((System.Data.DataRowView)(e.Row.DataItem)).Row["TempId"].ToString();
    }
}

Design

<asp:GridView runat="server" ID="grid" OnRowDataBound="grid_RowDataBound" AutoGenerateColumns="false">
   <Columns>
      <asp:TemplateField HeaderText="RunDate">
         <ItemTemplate>
             <asp:DropDownList runat="server" ID="DropDownList1" />
         </ItemTemplate>
       </asp:TemplateField>
      <asp:BoundField HeaderText="TempID" DataField="TempID" />
   </Columns>
</asp:GridView>

Answer 2

When you bind the gridview you must also bind the primary key to some template field control,if you have not written it then add hidden field and bind to it as follow

 <ItemTemplate>
            <asp:HiddenField runat="server" ID="hiddenfield1" Value='<%# Eval("TempID") %>' />
            <asp:DropDownList runat="server" ID="ddl" />
 </ItemTemplate>

In RowDataBound Event you can findout the PrimaryKey and then use it to set the Dropdown Selected Value as follow...

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DataTable dt = new DataTable();
        dt = Common.rundate();
        DropDownList ddl = e.Row.FindControl("DropDownList1") as DropDownList;

        ddl.DataTextField = "RunDate";
        ddl.DataValueField = "TempID";
        ddl.DataSource = dt;
        ddl.DataBind();

        HiddenField hdn=(HiddenField)row.Cells[cellindex].FindControl("hiddenField1");
        ddl.SelectedValue=hdn.Value;
    }

}

Answer 3

I am still not convinced by my solution, but I think this is the way I would go about it...

When loading the data in the first time I would fill a dictionary with the run dates for each name:

    private Dictionary<string, List<DateTime>> runDates = new Dictionary<string, List<DateTime>>();

    private void LoadData()
    {
        DataTable table = new DataTable();
        table.Columns.Add("TempName", typeof(string));

        using (var connection = new SqlConnection("YourConnectionString"))
        using (var command = new SqlCommand("SELECT DISTINCT TempName, RunDate FROM History_Table;", connection))
        {
            connection.Open();
            using (var reader = command.ExecuteReader())
            {
                while (reader.Read())
                {
                    string tempName = reader.GetString(0);
                    if (!runDates.ContainsKey(tempName))
                    {
                        DataRow row = table.NewRow();
                        row[0] = tempName;
                        table.Rows.Add(row);
                        runDates.Add(tempName, new List<DateTime>());
                    }
                    runDates[tempName].Add(reader.GetDateTime(1));
                }
            }

            GridView1.DataSource = table;
            GridView1.DataBind();
        }
    }

When reading each row it checks if the name already exists, if it does not then it adds it to the table that will be used to bind the GridView and to the dictionary. Then in the binding event use the name label to find the list of dates from the dictionary:

    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            //Find the label with the temp name and assign it
            string tempName = (e.Row.FindControl("Label1") as Label).Value;

            DropDownList ddl = e.Row.FindControl("DropDownList1") as DropDownList;

            ddl.DataTextField = "RunDate";
            ddl.DataValueField = "TempID";
            ddl.DataSource = runDates[tempName];
            ddl.DataBind();
        }

    }

I toyed with various other ideas, one was returning the date list as an xml field with a unique list of names (much like in your previous question), storing this in a hidden field and deserialising on the row databound event, another solution was to generate 2 tables in the data set and define relationships, but this is very similar in principle to the method I have proposed, and I think I prefer this one...