Readme.md

Grid View for ASP.NET Web Forms - How to use the WebMethod attribute to update data in particular grid columns

This example demonstrates how to create data item templates and use the WebMethod attribute to update data in templated columns without refreshing the entire grid.

Overview

Follow the steps below:

1. Specify a column's DataItemTemplate property and add a control to the template. In the control's Init event handler, specify the control's ClientInstanceName property based on the row's key value.

   <dx:GridViewDataSpinEditColumn FieldName="C2" Caption="Numeric (Live)">
       <DataItemTemplate>
           <dx:ASPxLabel ID="labelC1" runat="server" Text='<%# Eval("C2") %>' OnInit="labelC1_Init" />
       </DataItemTemplate>
   </dx:GridViewDataSpinEditColumn>
   <dx:GridViewDataCheckColumn FieldName="C4" Caption="Boolean (Live)">
       <DataItemTemplate>
           <dx:ASPxCheckBox ID="cbC4" runat="server" Value='<%# Convert.ToBoolean(Eval("C4")) %>'
               ReadOnly="true" OnInit="cbC4_Init" />
       </DataItemTemplate>
   </dx:GridViewDataCheckColumn>

   protected void labelC1_Init(object sender, EventArgs e) {
       ASPxLabel label = sender as ASPxLabel;
       GridViewDataItemTemplateContainer container = label.NamingContainer as GridViewDataItemTemplateContainer;
       label.ClientInstanceName = "labelC1_" + container.KeyValue;
   }
   protected void cbC4_Init(object sender, EventArgs e) {
       ASPxCheckBox cb = sender as ASPxCheckBox;
       GridViewDataItemTemplateContainer container = cb.NamingContainer as GridViewDataItemTemplateContainer;
       cb.ClientInstanceName = "cbC4_" + container.KeyValue;
   }

2. Send a request to the server to get new values and use the WebMethod attribute to pass the values to the client.

   PageMethods.GetUpdatedDataFromServer(keys, onSucess, onError);

   [WebMethod]
   public static string GetUpdatedDataFromServer(int[] keys) {
       ChangeAllColumnDataRandomly();
       List<GridDataItem> GridData = GetDataSource();
       List<GridDataItem> newDataRequiredForClient = new List<GridDataItem>();
   
       foreach (int keyValue in keys) {
           GridDataItem item = GridData.Find(x => x.ID == keyValue);
           newDataRequiredForClient.Add(item);
       }
       var jsonSerialiser = new JavaScriptSerializer();
       var json = jsonSerialiser.Serialize(newDataRequiredForClient);
       return json;
   }
   public static void ChangeAllColumnDataRandomly() {
       // ...
   }
   public static List<GridDataItem> GetDataSource() {
       // ...
   }

3. Update data in templated columns on the client side or specify an error message.

   function onSucess(result) {
       var items = JSON.parse(result);
       for (var i = 0; i < items.length; i++) {
           var label = ASPxClientControl.GetControlCollection().GetByName("labelC1_" + items[i].ID);
           label.SetText(items[i].C2);
           var checkBox = ASPxClientControl.GetControlCollection().GetByName("cbC4_" + items[i].ID);
           checkBox.SetChecked(items[i].C4);
       }
   }
   function onError(result) {
       alert('Something wrong!');
   }

Files to Review

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

Documentation

• Grid View Temlplates
• Access Controls in Templates on the Server

More Examples

• How to display dynamic data within the ASPxGridView (Live Data) without full grid updating using the ASPxCallback control

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