Me again!!!! :D how are you all?!

Yet again I come cap in hand looking for more help - in the words of Oliver Twist (ok, Charles Dickens if you want to be pedantic): "please sir, can i have some more?!"

I have created a datagrid which contains two bound Columns and the a template column, into which I have placed a drop down list which selects values from my database. The problem lies in populating this dropdown list. When I am referencing it from the vb.aspx page, it wont recoginse the name I have given it. I have tried various things to try and find my way around this such as putting the datagrid name before the name of the list etc. Tried to make it a child object and a few other things, but they didnt want to work either.

I appreciate that I could hard code the values into the aspx page using the following tag, <asp:ListItem>, but I would be keen to avoid this. So anyone got any ideas please?

many thanks,

Morris

you can got the list in the itemdataBound event for the grid

try to get the control using findcontrol like
If e.Item.ItemIndex = -1 And e.Item.Cells(4).HasControls Then
   CType(e.Item.Cells(4).FindControl("DropDownList1") , DropDownList).datasource=createdatasource
   CType(e.Item.Cells(4).FindControl("DropDownList1") , DropDownList).DataTextField="Name"
   CType(e.Item.Cells(4).FindControl("DropDownList1") , DropDownList).DatavalueField="value"
        End If



Ahmed Ali
Software Developer

Alternatively, you could create a protected datasource on the page and use databinding syntax within the markup for the dropdownlist in the datagrid template to automatically bind the dropdownlist for each datagrid item...

<asp:dropdownlist Runat="server" ID="ddlList"
DataSource="<%# myProtectedDataSource%>"
DataTextField="datasource property/field for text of option"
DataValueField="datasource property/field for value of option" />

Create the datagrid's datasource once as a class scope protected member, and populate the datasource once in page load (based on postback). This same datasource will be used by every member DDL of datagrid. The datasource can be any datasource you would normally use: DataSet, DataTable, object collection, arraylist, etc.

The harder part of this is preselecting the DDL item (if you need to). You'll have to do this in the ItemDataBound handler:

If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = ListItemType.AlternatingItem Then
    Dim objDDL As DropDownList = CType(e.Item.FindControl("ddlList"), DropDownList)
    objDDL.SelectedIndex = objDDL.Items.IndexOf(objDDL.Items.FindByValue(<dataitem value>))
End If

You'll need to replace <dataitem value> with a conversion to the appropriate dataitem object that the griditem is bound to (like a table row). Then you need to get the value. The source object for the conversion is e.Item.DataItem which returns the dataitem that the current datagrid item is bound to.

For example...
CType(e.Item.DataItem, System.Data.DataRow).Item("myColumn").ToString

Peter
------------------------------------------------------
Work smarter, not harder.

  i have a question from where i can get this source
"<%# myProtectedDataSource%>"
and how i can create????


Ahmed Ali
Software Developer

You must create this data source in your codebehind. The member must be class scope:

Public Class MyASPXPage
    ...
    Protected myDataSet As DataSet
       or
    Protected myArrayList As ArrayList
       or
    ...
End Class

Then you populate that data source in Page_Load(). The ASPX page runs in the context of a class inherited from the code behind class so it can access this datasource by its simple name. Then you need only fill in the necessary attributes of the list control (datagrid or other) to work with that data source. If it's a DataSet you might need to specify the table name in the DataMember attribute.

Peter
------------------------------------------------------
Work smarter, not harder.

Good day,

I think wrox should create a forum just for me at the moment with the amount of posts I am making at the moment. I appologise for cluttering the place up.

At the moment,I am geting this error at the moment: 'Object reference not set to an instance of an object' - do anyone know anything about it?

I following the advice from given earlier the datagrids are now bound to a data source, but i an other problem. Trying to get the value out of the lists is proving to a little bit on the hard side.

In a previous post i was working with checkboxes etc and I assumed that the code should be similar when extracting values from a dropdownlist as it would be for extracting values from a text box etc. However, I am getting the following error: 'System.NullReferenceException: Object reference not set to an instance of an object.' when I try to run the code. The code is below:

Dim ddlSelected As System.Web.UI.WebControls.DropDownList

        Dim ddCompValue As DataGridItem

        ddlSelected = ddCompValue.FindControl("ddCompValue")

        For Each ddCompValue In dgEmps.Items

            'get primary key of the data grid
            compID = Convert.ToInt32(dgEmps.DataKeys(ddCompValue.ItemIn dex).ToString())

            Dim rating As Integer = Convert.ToInt32(ddCompValue.ItemIndex.ToString)

            strSQL_rating = "INSERT INTO EMP_EVALUATION ( ECR_EMPLOYEE_ID, ECR_EVALUATION_DT, ECR_COMPETENCY_ID, ECR_PROFICENCY_LVL_CD ) Vaules (" & emp_id & "," & evaldt & "," & compID & "," & rating & ");"

            Dim ratingCmd As OleDbCommand = New OleDbCommand(strSQL_rating, dbConn)
            ratingCmd.CommandType = CommandType.Text

            'Execute the new rating query
            ratingCmd.ExecuteNonQuery()

        Next

the code is falling over at the following line: ddlSelected = ddCompValue.FindControl("ddCompValue") and I have no idea why - surely when working with datagrid item, the procedure should be the same for all the others?

As always - all help gratefully recieved!

Morris

Hi there,

Don't worry about "cluttering up" this forum. It's made for this, isn't it? You could, however, decide to create a new thread for a new topic, as this will make things a little clearer.

It seems to make sense you get that error. Take a look at this:

Dim ddCompValue As DataGridItem
ddlSelected = ddCompValue.FindControl("ddCompValue")
For Each ddCompValue In dgEmps.Items

As you can see, you declare a DataGridItem in the first line. The next line, then, tries to use the FindControl method of the DataGridItem. However, the DataGridItem isn't an object yet; all it is, is a variable declaration.

I think your DataGridItem should be retrieved from the Items collection of the DataGrid inside a loop, just as you did with the check boxes. If you get each DataGridItem from the DataGrid, then inside the For Each loop, the DataGridItem will be a real instance, so you can use its FindControl method to get at the drop down list.

Does this help?

Imar


---------------------------------------
Imar Spaanjaars
Everyone is unique, except for me.

yeah, that worked.

I just wasnt paying attention to what I was doing - oops!

Thanks

Morris

for those who are interested in seeing how to bind a drop down list to a datasource for ASP.NET this is a bit of C# code behind that will do it.

public void DataGrid1_DataBound(Object sender, DataGridItemEventArgs e)
        {
            if ((DataGrid1.EditItemIndex > -1)&&(e.Item.Cells[1].HasControls()))
            {
                Control myControl1 = e.Item.Cells[1].FindControl("ddlInspectors");
                if(myControl1!=null)
                {
                    DropDownList ddlInspectors = (DropDownList) e.Item.Cells[1].FindControl("ddlInspectors");
                    ddlInspectors.DataTextField = "ASPECTID";
                    ddlInspectors.DataValueField = "ASPECTID";
                    ddlInspectors.DataSource = ds.Tables[1].DefaultView;
                    ddlInspectors.DataBind();
                }
            }
        }


this is how you can get the selected value back from the datagrid's code behind updatd command:
        public void DataGrid1_Update(Object sender, DataGridCommandEventArgs e)
        {
            Control myControl1 = e.Item.Cells[1].FindControl("ddlInspectors");
            if(myControl1!=null)
            {
                DropDownList ddlInspectors = (DropDownList) e.Item.Cells[1].FindControl("ddlInspectors");
                Response.Write(ddlInspectors.SelectedValue.ToStrin g());
            }
}

Hi,

  I have two item templates with two dropdown. On selection of the first dropdown , i need to select the second dropdown. If any links are samples available let me know.

Reply to : [email protected]



Regards,
Govind.