Hello,

I have a Web Part that contains a relatively simple DataGrid, paginated 
across four pages. Switching between pages 2, 3 and 4 works fine, but if you 
request the first (0th) page again, the PageIndexChanged event does not fire. 
Please see my code below:

1        public class ListOfDataWebPart : WebPart
2        {
3    
4            protected DataGrid TestDataGrid;
5            protected DataSet pt_dgData;
6    
7            /// <summary>
8            /// Prepare data to display in the datagrid on first page request
9            /// </summary>
10           /// <param name="e"></param>
11           protected override void OnLoad(EventArgs e)
12           {
13               base.OnLoad(e);
14   
15               if (!this.Page.IsPostBack)
16               {
17                   pt_dgData = GetDataSource();
18                   ViewState["dgData"] = pt_dgData;
19               }
20           }
21   
22           /// <summary>
23           /// Render the web part, and controls contained therein
24           /// </summary>
25           /// <param name="writer"></param>
26           protected override void Render(System.Web.UI.HtmlTextWriter 
writer)
27           {
28               this.Title = "List of Data";
29               this.AllowClose = false;
30               this.AllowMinimize = false;
31               this.AllowEdit = false;
32   
33               TestDataGrid.RenderControl(writer);
34   
35               writer.Write("Current page shown in grid: " + 
TestDataGrid.CurrentPageIndex);
36           }
37   
38           /// <summary>
39           /// Add additional controls to the web part
40           /// </summary>
41           protected override void CreateChildControls()
42           {
43               GetDataGrid();
44   
45               base.CreateChildControls();
46           }
47   
48           /// <summary>
49           /// Create, populate, event handle and stylise the datagrid 
control
50           /// </summary>
51           private void GetDataGrid()
52           {
53               // core grid
54               TestDataGrid = new DataGrid();
55               TestDataGrid.ID = "TestDG";
56               TestDataGrid.AllowPaging = true;
57               TestDataGrid.PageSize = 5;
58               TestDataGrid.PagerStyle.Mode = PagerMode.NumericPages;
59               TestDataGrid.AutoGenerateColumns = false;
60               TestDataGrid.EnableViewState = true;
61   
62               // styles
63               TestDataGrid.CellPadding = 1;
64               TestDataGrid.GridLines = GridLines.None;
65               TestDataGrid.Width = new Unit(100, UnitType.Percentage);
66               TestDataGrid.ItemStyle.CssClass = "ms-vb2";
67               TestDataGrid.AlternatingItemStyle.CssClass = 
"ms-alternating ms-vb2";
68               TestDataGrid.HeaderStyle.CssClass = "ms-vh2-nofilter";
69               TestDataGrid.PagerStyle.CssClass = "ms-menutoolbar 
ms-toolbar";
70               TestDataGrid.PagerStyle.HorizontalAlign = 
HorizontalAlign.Right;
71   
72               // events
73               TestDataGrid.PageIndexChanged += new 
DataGridPageChangedEventHandler(TestDataGrid_PageIndexChanged);
74   
75               // columns
76               BoundColumn l_idCol = new BoundColumn();
77               l_idCol.HeaderText = "ID";
78               l_idCol.DataField = "ID";
79               TestDataGrid.Columns.Add(l_idCol);
80   
81               BoundColumn l_ValueCol = new BoundColumn();
82               l_ValueCol.HeaderText = "Value";
83               l_ValueCol.DataField = "Value";
84               TestDataGrid.Columns.Add(l_ValueCol);
85   
86               // rendering
87               RebindDG();
88               this.Controls.Add(TestDataGrid);
89           }
90   
91           /// <summary>
92           /// Change the page displayed within the datagrid control 
(seemingly fails to execute when 0th page requested)
93           /// </summary>
94           /// <param name="source"></param>
95           /// <param name="e"></param>
96           protected void TestDataGrid_PageIndexChanged(Object source, 
DataGridPageChangedEventArgs e)
97           {
98               this.Page.Response.Write("New page requested from grid: " + 
e.NewPageIndex);
99               TestDataGrid.CurrentPageIndex = e.NewPageIndex;
100              RebindDG();
101          }
102  
103          /// <summary>
104          /// Rebind the datagrid to the data held in ViewState
105          /// </summary>
106          private void RebindDG()
107          {
108              pt_dgData = (DataSet)ViewState["dgData"];
109  
110              TestDataGrid.DataSource = pt_dgData;
111              TestDataGrid.DataBind();
112          }
113  
114          /// <summary>
115          /// Create a dummy dataset to test the control
116          /// </summary>
117          /// <returns>The DataSet to bind to the grid</returns>
118          private DataSet GetDataSource()
119          {
120              DataSet l_ds = new DataSet();
121              DataTable l_dt = new DataTable();
122              DataRow l_row;
123  
124              l_dt.Columns.Add("ID", typeof(int));
125              l_dt.Columns.Add("Value", typeof(string));
126  
127              // create 20 entries with the row number in the ID column 
and a random string in the Value column
128              for (int i = 0; i < 20; i++)
129              {
130                  l_row = l_dt.NewRow();
131                  l_row[0] = i;
132                  l_row[1] = Guid.NewGuid().ToString();
133                  l_dt.Rows.Add(l_row);
134              }
135              l_ds.Tables.Add(l_dt);
136              
137              return l_ds;
138          }
139  
140      }

Writing the values back to the screen show that when the nth page is 
requested the messages show the correct values, but the 0th page only shows 
the current page number, not the requested one as well.

I have seen a few articles on problems with this event not firing at all, 
but this doesn't seem to be my issue. The one post I found that seemed to 
match this problem didn't have a reply :'( . Does anyone have any pointers?

Thanks,

Marc

I swear this question came up 3 weeks ago - there about. Have a google in 
here for the solution.

-- 
Regards,
Alvin Bruney
------------------------------------------------------
Shameless author plug
Excel Services for .NET is coming...
https://www.microsoft.com/MSPress/books/10933.aspx
OWC Black Book www.lulu.com/owc
Professional VSTO 2005 - Wrox/Wiley


"Marc Woolfson"  wrote in message 
news:C4FB3DB2-DD3E-411F-9B52-3C8D1D558D40@microsoft.com...

> Hello,
>
> I have a Web Part that contains a relatively simple DataGrid, paginated
> across four pages. Switching between pages 2, 3 and 4 works fine, but if 
> you
> request the first (0th) page again, the PageIndexChanged event does not 
> fire.
> Please see my code below:
>
> 1        public class ListOfDataWebPart : WebPart
> 2        {
> 3
> 4            protected DataGrid TestDataGrid;
> 5            protected DataSet pt_dgData;
> 6
> 7            /// <summary>
> 8            /// Prepare data to display in the datagrid on first page 
> request
> 9            /// </summary>
> 10           /// <param name="e"></param>
> 11           protected override void OnLoad(EventArgs e)
> 12           {
> 13               base.OnLoad(e);
> 14
> 15               if (!this.Page.IsPostBack)
> 16               {
> 17                   pt_dgData = GetDataSource();
> 18                   ViewState["dgData"] = pt_dgData;
> 19               }
> 20           }
> 21
> 22           /// <summary>
> 23           /// Render the web part, and controls contained therein
> 24           /// </summary>
> 25           /// <param name="writer"></param>
> 26           protected override void Render(System.Web.UI.HtmlTextWriter
> writer)
> 27           {
> 28               this.Title = "List of Data";
> 29               this.AllowClose = false;
> 30               this.AllowMinimize = false;
> 31               this.AllowEdit = false;
> 32
> 33               TestDataGrid.RenderControl(writer);
> 34
> 35               writer.Write("Current page shown in grid: " +
> TestDataGrid.CurrentPageIndex);
> 36           }
> 37
> 38           /// <summary>
> 39           /// Add additional controls to the web part
> 40           /// </summary>
> 41           protected override void CreateChildControls()
> 42           {
> 43               GetDataGrid();
> 44
> 45               base.CreateChildControls();
> 46           }
> 47
> 48           /// <summary>
> 49           /// Create, populate, event handle and stylise the datagrid
> control
> 50           /// </summary>
> 51           private void GetDataGrid()
> 52           {
> 53               // core grid
> 54               TestDataGrid = new DataGrid();
> 55               TestDataGrid.ID = "TestDG";
> 56               TestDataGrid.AllowPaging = true;
> 57               TestDataGrid.PageSize = 5;
> 58               TestDataGrid.PagerStyle.Mode = PagerMode.NumericPages;
> 59               TestDataGrid.AutoGenerateColumns = false;
> 60               TestDataGrid.EnableViewState = true;
> 61
> 62               // styles
> 63               TestDataGrid.CellPadding = 1;
> 64               TestDataGrid.GridLines = GridLines.None;
> 65               TestDataGrid.Width = new Unit(100, UnitType.Percentage);
> 66               TestDataGrid.ItemStyle.CssClass = "ms-vb2";
> 67               TestDataGrid.AlternatingItemStyle.CssClass =
> "ms-alternating ms-vb2";
> 68               TestDataGrid.HeaderStyle.CssClass = "ms-vh2-nofilter";
> 69               TestDataGrid.PagerStyle.CssClass = "ms-menutoolbar
> ms-toolbar";
> 70               TestDataGrid.PagerStyle.HorizontalAlign =
> HorizontalAlign.Right;
> 71
> 72               // events
> 73               TestDataGrid.PageIndexChanged += new
> DataGridPageChangedEventHandler(TestDataGrid_PageIndexChanged);
> 74
> 75               // columns
> 76               BoundColumn l_idCol = new BoundColumn();
> 77               l_idCol.HeaderText = "ID";
> 78               l_idCol.DataField = "ID";
> 79               TestDataGrid.Columns.Add(l_idCol);
> 80
> 81               BoundColumn l_ValueCol = new BoundColumn();
> 82               l_ValueCol.HeaderText = "Value";
> 83               l_ValueCol.DataField = "Value";
> 84               TestDataGrid.Columns.Add(l_ValueCol);
> 85
> 86               // rendering
> 87               RebindDG();
> 88               this.Controls.Add(TestDataGrid);
> 89           }
> 90
> 91           /// <summary>
> 92           /// Change the page displayed within the datagrid control
> (seemingly fails to execute when 0th page requested)
> 93           /// </summary>
> 94           /// <param name="source"></param>
> 95           /// <param name="e"></param>
> 96           protected void TestDataGrid_PageIndexChanged(Object source,
> DataGridPageChangedEventArgs e)
> 97           {
> 98               this.Page.Response.Write("New page requested from grid: " 
> +
> e.NewPageIndex);
> 99               TestDataGrid.CurrentPageIndex = e.NewPageIndex;
> 100              RebindDG();
> 101          }
> 102
> 103          /// <summary>
> 104          /// Rebind the datagrid to the data held in ViewState
> 105          /// </summary>
> 106          private void RebindDG()
> 107          {
> 108              pt_dgData = (DataSet)ViewState["dgData"];
> 109
> 110              TestDataGrid.DataSource = pt_dgData;
> 111              TestDataGrid.DataBind();
> 112          }
> 113
> 114          /// <summary>
> 115          /// Create a dummy dataset to test the control
> 116          /// </summary>
> 117          /// <returns>The DataSet to bind to the grid</returns>
> 118          private DataSet GetDataSource()
> 119          {
> 120              DataSet l_ds = new DataSet();
> 121              DataTable l_dt = new DataTable();
> 122              DataRow l_row;
> 123
> 124              l_dt.Columns.Add("ID", typeof(int));
> 125              l_dt.Columns.Add("Value", typeof(string));
> 126
> 127              // create 20 entries with the row number in the ID column
> and a random string in the Value column
> 128              for (int i = 0; i < 20; i++)
> 129              {
> 130                  l_row = l_dt.NewRow();
> 131                  l_row[0] = i;
> 132                  l_row[1] = Guid.NewGuid().ToString();
> 133                  l_dt.Rows.Add(l_row);
> 134              }
> 135              l_ds.Tables.Add(l_dt);
> 136
> 137              return l_ds;
> 138          }
> 139
> 140      }
>
> Writing the values back to the screen show that when the nth page is
> requested the messages show the correct values, but the 0th page only 
> shows
> the current page number, not the requested one as well.
>
> I have seen a few articles on problems with this event not firing at all,
> but this doesn't seem to be my issue. The one post I found that seemed to
> match this problem didn't have a reply :'( . Does anyone have any 
> pointers?
>
> Thanks,
>
> Marc 

Hi Alvin,

I think I found the post you are referring to 
(http://groups.google.co.uk/group/microsoft.public.dotnet.framework.aspnet.webcontrols/browse_thread/thread/5d2d46c629871c9a/d0e60f550ec24b09) 
but the original poster wasn't very generous in explaining the resolution, 
and neither have other people 
(http://groups.google.co.uk/group/microsoft.public.dotnet.framework.aspnet.datagridcontrol/browse_thread/thread/a1038800585554d2/86d7d023a8b58a1c). 
Another old post 
(http://groups.google.co.uk/group/microsoft.public.dotnet.framework.aspnet.datagridcontrol/browse_thread/thread/e4f6db992a15f201/ccce5ffc1396079e#ccce5ffc1396079e) 
had a similar issue but this was resolved by setting ViewState = true on the 
DataGrid. Mine already has this setting.

The more I look at this, the more it seems that I am creating and binding 
the dynamic control at the wrong stage in the ASP.NET life cycle. I have 
tried putting trace messages everywhere and analysing the results, and it 
seems that, as the last post above, the DataGrid gets recreated *twice* upon 
most Postbacks. Should its creation be moved out of the CreateChildControls() 
method and into (e.g.) the OnInit()?

Thanks,

Marc

"Alvin Bruney [MVP]" wrote:


> I swear this question came up 3 weeks ago - there about. Have a google in 
> here for the solution.
> 
> -- 
> Regards,
> Alvin Bruney

Hi again,

I found one post which resolved a similar issue by databinding the grid in 
the PreRender event. I tried this, which seemed to fix the '0th page' 
problem. 

I still have an issue with multiple databinding upon postbacks which now 
seems to be preventing my Command event from firing - or more precisely, 
reporting it as firing in the trace - and having an effect on the rendered 
grid. I also have a SortCommand event which as well as sorting the data 
writes a value to ViewState. This is definitely getting executed as that 
particular value is changing, but the grid is seemingly only sorting 
correctly on the second databind, so the trace doesn't even show evidence of 
the SortCommand itself being fired.

It would be great if MS provided an example of DataGrids as dynamic controls 
with all relevant events/GUI controls working as desired...

"Alvin Bruney [MVP]" wrote:


> I swear this question came up 3 weeks ago - there about. Have a google in 
> here for the solution.
> 
> -- 
> Regards,
> Alvin Bruney

Make sure that on the first page_load, you are calling the grid's databind 
method.  But, on subsequent loads, it should NOT be in Page_Load, but 
instead have it in the various eventhandlers for your gird 
(PageIndexChanged, EditCommand, DeleteCommand, UpdateCommand, SortCommand, 
etc.).


"Marc Woolfson"  wrote in message 
news:C4FB3DB2-DD3E-411F-9B52-3C8D1D558D40@microsoft.com...

> Hello,
>
> I have a Web Part that contains a relatively simple DataGrid, paginated
> across four pages. Switching between pages 2, 3 and 4 works fine, but if 
> you
> request the first (0th) page again, the PageIndexChanged event does not 
> fire.
> Please see my code below:
>
> 1        public class ListOfDataWebPart : WebPart
> 2        {
> 3
> 4            protected DataGrid TestDataGrid;
> 5            protected DataSet pt_dgData;
> 6
> 7            /// <summary>
> 8            /// Prepare data to display in the datagrid on first page 
> request
> 9            /// </summary>
> 10           /// <param name="e"></param>
> 11           protected override void OnLoad(EventArgs e)
> 12           {
> 13               base.OnLoad(e);
> 14
> 15               if (!this.Page.IsPostBack)
> 16               {
> 17                   pt_dgData = GetDataSource();
> 18                   ViewState["dgData"] = pt_dgData;
> 19               }
> 20           }
> 21
> 22           /// <summary>
> 23           /// Render the web part, and controls contained therein
> 24           /// </summary>
> 25           /// <param name="writer"></param>
> 26           protected override void Render(System.Web.UI.HtmlTextWriter
> writer)
> 27           {
> 28               this.Title = "List of Data";
> 29               this.AllowClose = false;
> 30               this.AllowMinimize = false;
> 31               this.AllowEdit = false;
> 32
> 33               TestDataGrid.RenderControl(writer);
> 34
> 35               writer.Write("Current page shown in grid: " +
> TestDataGrid.CurrentPageIndex);
> 36           }
> 37
> 38           /// <summary>
> 39           /// Add additional controls to the web part
> 40           /// </summary>
> 41           protected override void CreateChildControls()
> 42           {
> 43               GetDataGrid();
> 44
> 45               base.CreateChildControls();
> 46           }
> 47
> 48           /// <summary>
> 49           /// Create, populate, event handle and stylise the datagrid
> control
> 50           /// </summary>
> 51           private void GetDataGrid()
> 52           {
> 53               // core grid
> 54               TestDataGrid = new DataGrid();
> 55               TestDataGrid.ID = "TestDG";
> 56               TestDataGrid.AllowPaging = true;
> 57               TestDataGrid.PageSize = 5;
> 58               TestDataGrid.PagerStyle.Mode = PagerMode.NumericPages;
> 59               TestDataGrid.AutoGenerateColumns = false;
> 60               TestDataGrid.EnableViewState = true;
> 61
> 62               // styles
> 63               TestDataGrid.CellPadding = 1;
> 64               TestDataGrid.GridLines = GridLines.None;
> 65               TestDataGrid.Width = new Unit(100, UnitType.Percentage);
> 66               TestDataGrid.ItemStyle.CssClass = "ms-vb2";
> 67               TestDataGrid.AlternatingItemStyle.CssClass =
> "ms-alternating ms-vb2";
> 68               TestDataGrid.HeaderStyle.CssClass = "ms-vh2-nofilter";
> 69               TestDataGrid.PagerStyle.CssClass = "ms-menutoolbar
> ms-toolbar";
> 70               TestDataGrid.PagerStyle.HorizontalAlign =
> HorizontalAlign.Right;
> 71
> 72               // events
> 73               TestDataGrid.PageIndexChanged += new
> DataGridPageChangedEventHandler(TestDataGrid_PageIndexChanged);
> 74
> 75               // columns
> 76               BoundColumn l_idCol = new BoundColumn();
> 77               l_idCol.HeaderText = "ID";
> 78               l_idCol.DataField = "ID";
> 79               TestDataGrid.Columns.Add(l_idCol);
> 80
> 81               BoundColumn l_ValueCol = new BoundColumn();
> 82               l_ValueCol.HeaderText = "Value";
> 83               l_ValueCol.DataField = "Value";
> 84               TestDataGrid.Columns.Add(l_ValueCol);
> 85
> 86               // rendering
> 87               RebindDG();
> 88               this.Controls.Add(TestDataGrid);
> 89           }
> 90
> 91           /// <summary>
> 92           /// Change the page displayed within the datagrid control
> (seemingly fails to execute when 0th page requested)
> 93           /// </summary>
> 94           /// <param name="source"></param>
> 95           /// <param name="e"></param>
> 96           protected void TestDataGrid_PageIndexChanged(Object source,
> DataGridPageChangedEventArgs e)
> 97           {
> 98               this.Page.Response.Write("New page requested from grid: " 
> +
> e.NewPageIndex);
> 99               TestDataGrid.CurrentPageIndex = e.NewPageIndex;
> 100              RebindDG();
> 101          }
> 102
> 103          /// <summary>
> 104          /// Rebind the datagrid to the data held in ViewState
> 105          /// </summary>
> 106          private void RebindDG()
> 107          {
> 108              pt_dgData = (DataSet)ViewState["dgData"];
> 109
> 110              TestDataGrid.DataSource = pt_dgData;
> 111              TestDataGrid.DataBind();
> 112          }
> 113
> 114          /// <summary>
> 115          /// Create a dummy dataset to test the control
> 116          /// </summary>
> 117          /// <returns>The DataSet to bind to the grid</returns>
> 118          private DataSet GetDataSource()
> 119          {
> 120              DataSet l_ds = new DataSet();
> 121              DataTable l_dt = new DataTable();
> 122              DataRow l_row;
> 123
> 124              l_dt.Columns.Add("ID", typeof(int));
> 125              l_dt.Columns.Add("Value", typeof(string));
> 126
> 127              // create 20 entries with the row number in the ID column
> and a random string in the Value column
> 128              for (int i = 0; i < 20; i++)
> 129              {
> 130                  l_row = l_dt.NewRow();
> 131                  l_row[0] = i;
> 132                  l_row[1] = Guid.NewGuid().ToString();
> 133                  l_dt.Rows.Add(l_row);
> 134              }
> 135              l_ds.Tables.Add(l_dt);
> 136
> 137              return l_ds;
> 138          }
> 139
> 140      }
>
> Writing the values back to the screen show that when the nth page is
> requested the messages show the correct values, but the 0th page only 
> shows
> the current page number, not the requested one as well.
>
> I have seen a few articles on problems with this event not firing at all,
> but this doesn't seem to be my issue. The one post I found that seemed to
> match this problem didn't have a reply :'( . Does anyone have any 
> pointers?
>
> Thanks,
>
> Marc 

> The more I look at this, the more it seems that I am creating and binding
> the dynamic control at the wrong stage in the ASP.NET life cycle. I have
> tried putting trace messages everywhere and analysing the results, and it
> seems that, as the last post above, the DataGrid gets recreated *twice* 
> upon
> most Postbacks. Should its creation be moved out of the 
> CreateChildControls()
> method and into (e.g.) the OnInit()?



No.
CreateChildControls is the place where all controls have to be created...

Also just ensure that the data-grid is not bound everytime in Page_Load!
Also ensure that the data-grid is bound for each command - Sort, Edit, 
Delete, Cancel, PagIndexChanged etc.


-- 
Happy Hacking,
Gaurav Vaish | www.mastergaurav.com
www.edujini-labs.com
http://eduzine.edujini-labs.com
-----------------------------------------