Grid View for ASP.NET Web Forms - How to use template editors to update grid data

This example demonstrates how to create a templated column, add an editor to the template, and update the data source on a callback when a user changes the editor's value.

Note
In v13.2 and higher, you can use the batch edit functionality to edit grid data on the client and send it to the server on a single request: Grid in Batch Edit Mode.

Overview

Specify a column's DataItemTemplate property and add an editor to the template. Handle the editor's server-side Init event and do the following in the handler:

• Access the template container to get the row's key value and the column's field name.
• Assign a client-side ValueChanged event handler to the editor and pass the corresponding grid values as parameters.

<dx:GridViewDataTextColumn FieldName="Item" VisibleIndex="2">
    <DataItemTemplate>
        <dx:ASPxComboBox ID="cmbItem" runat="server" ValueType="System.Int32" Value='<%#
        Eval("Item") %>' OnInit="editor_Init">
            <Items>
                <!-- ... -->
            </Items>
        </dx:ASPxComboBox>
    </DataItemTemplate>
</dx:GridViewDataTextColumn>

protected void editor_Init(object sender, EventArgs e) {
    ASPxEdit txt = sender as ASPxTextEdit;
    GridViewDataItemTemplateContainer container = txt.NamingContainer as GridViewDataItemTemplateContainer;

    txt.SetClientSideEventHandler("ValueChanged", String.Format(CallbackArgumentFormat,
        container.KeyValue,
        container.Column.FieldName));
}

In the editor's ValueChanged event handler, get the new editor's value and pass it to the server on a callback. To send a callback to the server, use a callback control and call its PerformCallback method. In the server-side Callback event handler, assign the editor's value to the XPO object and update the data source.

 function OnValueChanged(s, e, key, field) {
    var value = s.GetValue();
    if(s instanceof ASPxClientTextBox) { // encode text
        s.SetText(encodeHtml(s.GetText()));
        value = s.GetText();
    }
    if(s instanceof ASPxClientDateEdit)
        value = s.GetText();
    var param = key + "|" + field + "|" + value;
    cb.PerformCallback(param);
}

protected void cb_Callback(object source, DevExpress.Web.CallbackEventArgs e) {
    String[] p = e.Parameter.Split('|');

    Int32 key = Convert.ToInt32(p[0]);
    String field = p[1];
    Object value = p[2];

    MyObject obj = session.GetObjectByKey<MyObject>(key);

    switch (field) {
        case "Title":
            if (value.ToString() == "null")
                value = String.Empty;
            break;

        case "Item":
            value = Convert.ToInt32(value);
            break;

        case "SomeDate":
            DateTime result = DateTime.Now;
            if (DateTime.TryParse(value.ToString(), out result))
                value = result;
            else
                value = DateTime.Now;
            break;
    }

    obj.SetMemberValue(field, value);
    obj.Save();
}

Files to Review

• Default.aspx (VB: Default.aspx)
• Default.aspx.cs (VB: Default.aspx.vb)

Documentation

• Grid View Templates

More Examples

• How to update a boolean field using the ASPxCheckBox in a data item template

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