Tag Archives: solution

Access nested controls in ASP.NET Page PreInit event (when no Master Page is involved)

There’re situations when you need access ASP.NET web controls very early in page lifecycle, more specifically – in Page PreInit event – and you can, but only top-level controls. But what if you need to access child/nested controls? The example below uses Infragistics WebHierarchicalDataGrid as a child of Infragistics WebSplitter, but this pretty much applies to any such scenario.

Let’s say you have following layout

<ig:WebSplitter ID="WSP" runat="server">
   <Panes>
      <ig:SplitterPane runat="server">
         <Template>

            <ig:WebHierarchicalDataGrid ID="WHG" runat="server">
            </ig:WebHierarchicalDataGrid>

         </Template>
      </ig:SplitterPane>
      <ig:SplitterPane runat="server"></ig:SplitterPane>
   </Panes>
</ig:WebSplitter>

As you can see grid “WHG” is nested withing first pane of splittet “WSP. Let’s see what happens if you try access the controls in PagePreInit event: Continue reading →

Access jQueryUI dialog buttons after dialog was created

If you’re using jQuery UI Dialog, you know sometimes there’s a need to access dialog’s button objects after the dialog has already been created. This can be easily done via 

$(dialogElement).dialog("option").buttons

command. One possible scenario where this can be useful – is executing specific button click function when user clicks [X] in dialog title. Imagine that buttons are set via array and the last object in this array is always something like CANCEL or NO or DISREGARD – and you want to simulate click of that last button whenever user clicks [X]. Using above command it’s pretty straightforward:

$(oDivDialog).dialog({
   //... some dialog parameters
   buttons: arrayOfButtonObjects,
   //... some more parameters
   close: function () {
      var buttons = $(this).dialog("option").buttons;
      buttons[buttons.length - 1].click();
   }
})

Line 5 begins close event which is called on dialog closing.
Line 6 retrieves array of buttons for the dialog
Line 7 calls click() function of the last button in the array

Infragistics WebDataMenu: Manual postback from client-side Click event

There’s a a few possible scenarios when you need to manually to initiate server-side Click event of Infragistics WebDataMenu control. For example in client side click event you do some verification/user confirmation and upon positive confirmation (e.g. user clicks YES) – server-side Click event should kick in.

In a normal flow of event you can use set_cancel(bool) method to allow/disallow natural menu postback e.g.

function Menu_ItemClick(sender, eventArgs) {

   if (confirm('Are you sure?'))
       eventArgs.set_cancel(false)
   else
       eventArgs.set_cancel(true)

}

This works because this dialog stops code execution waiting for the user input. But what if you use something like jQueryUI dialog that relies on callback functions to get user feedback? In this case execution of the code continues immediately so you have to cancel postback right away and instead in the callback of the dialog initiate manual postback e.g

function Menu_ItemClick(sender, eventArgs) {

   $("#dialog").dialog({
      resizable: false,
      height:140,
      modal: true,
      buttons: {
        "Yes": function() {
          $(this).dialog("close");
          __doPostBack(sender.get_id(), 'ItemClick' + eventArgs._getPostArgs());
        },
        "No": function() {
          $(this).dialog("close");
        }
      }
   });  

   eventArgs.set_cancel(true)

}

The example above initiates modal confirmation jQuery UI dialog and immediately cancels menu postback (Line 18). Later if user clicks “Yes” button – dialog is closed and manual menu postback is initiated (Line 10) – it passes menu ID and correct postback argruments which result in server-side Click event of menu control. If user clicks “No” – dialog is closed and nothing else happens.

Solution for NFC not working on Samsung Galaxy phone

This has been bothering me for a while – NFC refused to work on my Samsung Galaxy phone. Service was enabled and running, no errors or warning were displayed, but phone was unable to detect any NFC presence – tags, stickers, point of sale etc.

I was wrecking my mind until I realized that a while back I replaced the original Samsung Battery with a higher capacity generic one to extend battery life. But original Samsung Battery acts as an NFC antenna as well!

As soon as I put original battery in – lo and behold NFC sprang to action.

Reenable (temporary) showModalDialog support in Chrome (for Windows) 37+

You know you shouldn’t use showModalDialog to open modal windows – it’s bad taste and prone to cause issues. Unfortunately many applications (especially Enterprise ones) rely on the method ability to halt code execution until the window closed (e.g. user answers a YES/NO question).

Tough luck, starting version 37 Google Chrome removed support for showModalDialog. Your code suddenly began to act in weird and unpredictable way. You definitely should rework it to use a different approach to dialogs. Fortunately Google gives you a bit more time. You can re-enable showModalDialog support, but only temporarily – until May of 2015. Continue reading →

Infragistics WebDataMenu flashes unexpected color on hover

WebDataMenu
Infragistics WebDataMenu ASP.NET control comes both with predefined stylesets and allows you granularly overwrite any of the styles. For example definition like this

<ig:WebDataMenu ID="xmyMenu" runat="server" StyleSetName="Office2007Blue"
                 CssClass ="topMenuStyle" >
   <GroupSettings Orientation="Horizontal" />
   <ItemSettings CssClass="itemCssStyle" 
                 HoverCssClass="hoverCssStyle" 
                 SelectedCssClass="selectedCssStyle" />  
</ig:WebDataMenu>

will create a horizontal dropdown menu in default “Office 2007 Blue” styleset but allows you to overwrite individual styles via exposed CSS properties.

Let’s take a look at hover style. Continue reading →

Infragistics WebDataGrid stalls on paging large datasets

A common scenario while using Infragistics WebDataGrid is to have an unbound column, whose cell’s value is determined at runtime in InitializeRow event, something like

Private Sub xmyGrid_InitializeRow(ByVal sender As Object, ByVal e As GridControls.RowEventArgs) Handles xmyGrid.InitializeRow
   '... some code
   e.Row.Items(0).Value = SomeCalculatedData
   '... some more code
End Sub

This works fine if you bind the grid to a small data set (and you should!) But if, due to circumstances out of your control, you bind it to a dataset with tens of thousand of records you might be screwed. Even if you enable paging (and you most definitely should!) you may find yourself living in a shotgun shack in a situation that changing page takes forever and eventually crashes. If you do – change the above line to 

e.Row.Items(0).Text = SomeCalculatedData

note using of .Text property, which is String, instead of .Value which is Object. Since you’re assigning the calculated data for presentation only – no need to change underlying value – and this makes all the difference.

How to make “scrollIntoView” apply to IFRAME only

Let’s say you have a really long HTML page with scrollbars, for the sake of argument something like this:

<div>aaaa</div>
<div>aaaa</div>
<div>aaaa</div>
...more content...
<div id="xB">bbbb</div>
<div>aaaa</div>
<div>aaaa</div>
<div>aaaa</div>
...much more content...

And somewhere, perhaps on pageload, you want to make sure that highlighted element is visible to the user, so to scroll it into view you execute

document.getElementById("xB").scrollIntoView();

And it works fine and well – the needed element is automatically displayed on top of the page. But what if this page is in an IFRAME and the parent page has a large scrollable content of it’s own:
Continue reading →

Infragistics WebSplitter: Set SplitterBar’s CSS class in clinet-side JavaScript

Hello there. Haven’t written in a while, been busy participating in Stack Overflow community, but this little bit I found interesting.

Infragistics has a cool versatile Web Splitter control in their ASP.NET suite, but recently I encountered a shortcoming – there’s no way to set a CSS class for splitter bar on client-side via JavaScript. On server-side you can do something like

xMySplitter.SplitterBar.CssClass = "hiddenElement";

On client-side – you can get the CSS class via

var sCss = $find('xMySplitter').get_splitterBarCss()

but there’s no counterpart set_splitterBarCss() method. Continue reading →

Solution for SqlDataReader.ReadColumnHeader NullReferenceException

This post related to the previous one, but I decided to write a separate article because it seems to be a common problem.

Sometimes when you use SqlDataReader, you would get an exception:

NullReferenceException {“Object reference not set to an instance of an object.”}
at System.Data.SqlClient.SqlDataReader.ReadColumnHeader(Int32 i)
at System.Data.SqlClient.SqlDataReader.ReadColumn(Int32 i, Boolean setTimeout)
at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)

And the maddening thing – it doesn’t happen often, just every once in a while. And it happens at different times too, sometimes reader would read 100 records, sometimes 200 etc.

One possible case – SqlDataReader is losing its connection. And one possible reason for that – connection goes out of scope.

Consider following scenario – you have a function that returns SqlDataReader:

Function GetTheReader() as SqlDataReader
   Dim oConn As New SqlConnection("Connection String") : oConn.Open()
   Dim oComm As New SqlCommand("Stored Procedure", oConn)

   Dim oReader As SqlDataReader = oComm.ExecuteReader(CommandBehavior.CloseConnection)

   Return oReader
End Function

And you use it like this:

Dim oReader as SqlDataReader = GetTheReader()
'Begin use reader - loop, read data etc.

The problem with this approach that connection used to create the reader is stored in a private variable inside of `GetTheReader` function and when the function exits – the variable goes out of scope. Eventually, sooner or later Garbage Collector will collect it and close and dispose of connection – and at this time your SqlDataReader will fail.

The solution? Either use SqlDataReader at the same scope level you created it, or, if you do need to use function – pass connection object into it as one of the parameters, so it would remain valid after function exits.