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Posts tagged: bug

WriteEndObject of JSON.NET ouptuts NULL literal

By , 01/07/2015 4:50 PM

JSON.NET is a very popular framework to process JSON data in .NET. We recently upgraded from v4 to v6 and noticed strange thing it started to output null to JSON strings created by JsonTextWriter object.

For example if JSON produced by v4 would look like this:

{"param1":"value1", "param2":"value2",
"someArray":[{"arrParam1": "arrValue1"}, {"arrParam2": "arrValue2"}]}

Same code, using v6, would prodcuce

{"param1":"value1", "param2":"value2",
"someArray":[{"arrParam1": "arrValue1"}, {"arrParam2": "arrValue2"}]null}

that extra “null” makes it invalid and unusable JSON.

The .NET function to create JSON writes it into a StringBuilder and is pretty straighforward.

  1. It starts with call to WriteStartObject method of JsonTextWriter
  2. Then it creates parameter name via WritePropertyName
  3. Depending on whether primitive value or raw string needs to be written WriteValue or WriteRaw methods are used respectfully
  4. Repeat steps 2 and 3 as needed
  5. Call to WriteEndObjectto finish writing.

This worked perfectly well when version 4 of Newtonsoft.Json.dll was used. After upgrading to version 6 last method – “WriteEndObject” began to output “null” to resulting JSON.

The solution is to use WriteRawValue method instead of WriteRaw – it still outputs raw string, but at the end WriteEndObject doesn’t output “null” anymore.

When SqlDataReader is missing rows

By , 08/27/2013 10:48 PM

I have a very basic scenario:

  1. Execute TSQL Stored procedure
  2. Return a DataReader
  3. Read data from the Reader

This is ADO.NET 101. There is one problem: DataReader loses rows. This problem has haunted me forever, extensive research and numerous suggestion didn’t help, even though the code is extremely basic:

Get the reader:

m_dbSel.CommandType = CommandType.StoredProcedure
m_dbSel.CommandText = "SP_Name"
oResult = m_dbSel.ExecuteReader()

Pass the reader to class constructor to fill Generic List (of Integer):

Public Sub New(i_oDataReader As Data.SqlClient.SqlDataReader)

    m_aFullIDList = New Generic.List(Of Integer)

    While i_oDataReader.Read
    End While

    m_iTotalNumberOfRecords = m_aFullIDList.Count

End Sub

This problem occurs when number of rows returned by the reader is relatively large (over 600,000 records). If this happens – number of rows added to the list from the reader is inconsistent, but always less than real one. Most often “magic” number of 524289 rows is returned.

Well, this is no longer a mystery, thanks to the great people from Stack Overflow @RBarryYoung, @granadaCoder and especially @MartinSmith who was the first to point me in the right direction – and here it is.

Even though the problem is with SqlDataReader – it is happening because it is used in conjunction with Generic List. List, as you may know has a flexible Capacity for number of elements it can store. When count of elements exceeds capacity – capacity increases and always to a power of 2. E.g.

When the count exceeds 4 elements – capacity is set to 8 (2^3)
When the count exceeds 8 elements – capacity is set to 16 (2^4)
When the count exceeds 16 elements – capacity is set to 32 (2^5)


This is what makes Generic List such a powerful tool, used by many large scale .NET projects, e.g. bingogodz.com. And ordinary this is not a problem. Unfortunately this is not the case when it is used together with SqlDataReader. When count of items in the List exceeds 524,288 (2^19) and its capacity is set to 1,048,576 (2^20) – SqlDataReader’s Read method suddenly returns False even though not all records have been read. No exception is thrown, it simple stops.

The only possible workaround I’ve found so far (I am still looking for better ones) is to pre-set List capacity in advance. Since, when using DataReader, you do not know number of rows, you’re left either with hardcoding the number or running another DB query to retrieve number of rows via something like COUNT(*). Like I said, I don’t like this workaround, please let me know if you find a better one.

UPDATE: Finally figured it out: http://stackoverflow.com/a/18520609/961695

WebHierarchicalDataGrid: get_scrollTop() returns incorrect value

By , 08/02/2013 12:52 PM

Infragistics WebHierarchicalDataGrid has a neat client-side built-in function get_scrollTop() – it is used if at any point you need to retrieve current vertical scroll position of the grid (e.g. to use it in your own calculations to display something at a specific position on the grid – tooltip, help, additional info etc.)

Unfortunately the function has a bug: its value only set if user actually manually scrolls the grid: using mouse and scrollbar on the right, keyboard etc. If no scrolling user-interaction is involved and scroll position changes due to other means (e.g. displayed data size changes) – the function retains original value, throwing all your calculation out of whack. Continue reading 'WebHierarchicalDataGrid: get_scrollTop() returns incorrect value'»

Solution for IE10 error: SCRIPT5022: Sys.ArgumentOutOfRangeException: Value must be an integer

By , 05/01/2013 2:05 PM

If you’re testing your ASP.NET project in Internet Explorer 10, you may encounter following error:

SCRIPT5022: Sys.ArgumentOutOfRangeException: Value must be an integer.
Parameter name: (x or y)
Actual value was (some floating point value)
ScriptResource.axd, line … character …

Often it come up when you use some 3rd party libraries, Telerik or Infragistics (in my case it happened in WebDataMenu control).

Here why it happens. Continue reading 'Solution for IE10 error: SCRIPT5022: Sys.ArgumentOutOfRangeException: Value must be an integer'»

Solution for WebHierarchicalDataGrid’s “Async request failed” error

By , 04/29/2013 4:28 PM

This is a solution for specific (and maybe somewhat obscure, but it helped me, so perhaps it will be helpful to someone else) scenario for Infragistics’ WebHierarchicalDataGrid error “Async request failed“.

It could be accompanied by inner errors

Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request

or more generic

Object Reference not set

In this particular scenario WHDG uses manual LoadOnDemand for to populate children (i.e. RowIslandPopulating event is used) and parent grid is sorted by one or more columns. Error is happening when attempting to expand second child or a grandchild. Continue reading 'Solution for WebHierarchicalDataGrid’s “Async request failed” error'»

Solution: eventArgs.get_type() incorrectly detects header of WebDataGrid in FireFox as cell

By , 02/07/2013 12:31 PM

If you use CSOM of Infragistics WebDataGrid you may encounter a bug in client-side event handlers. Let’s say some action is needed on double clicking of a grid cell. The handler looks something like this:

function xMyGrid_DoubleClick(sender, eventArgs) {
   if (eventArgs.get_type() == "cell") {
      //perform action

IF condition on line 2 makes sure that action is executed only if actual grid cell is double clicked. If you double click column header, eventArgs.get_type() would return "header" and the action would be skipped.

But not in FireFox. In that browser eventArgs.get_type() returns "cell" even when header is clicked. So an additional condition is needed. Grid column header is rendered as a TH HTML element and this is what we can check:

function xMyGrid_DoubleClick(sender, eventArgs) {
   if (eventArgs.get_type() == "cell" &&  eventArgs.get_item().get_element().tagName != 'TH') {
      //perform action

This solution works universally in all browsers.

Infragistics WebDataMenu last item disappears

By , 12/28/2012 1:14 PM

While using Infragistics WebDataMenu control from their NetAdvantage for ASP.NET Suite (version 2012.2, current as of this post) I noticed that last menu item in horizontal menu disappears. To me this only happened in Firefox.

Disappearing Act

This post suggested to set EnableScrolling menu property to False as a solution. Which is fine and well, but did not work for me since I need my menu to scroll (it has limited width available and menu items are added programmatically in code-behind so total items width can be wider than width available for the menu).

Continue reading 'Infragistics WebDataMenu last item disappears'»

Active CSS selector not working correctly for Input Button in IE

By , 08/16/2012 10:43 PM

CSS has a cool selector called “:active“, it can be used for example to select a button when it is pressed. Let’s say you have an HTML markup like this:

<input type="button" class="mybutton" value="Click me" />

and you define CSS selector like this:

.mybutton:active {background-color:red}

the button will change its background color to red when clicked and only for the duration of the click (while the mouse button is down) as soon as mouse button is released – background color is reverted to original.

This works fine in all modern browsers and supposed to work in Internet Explorer since version 8. And it works – well kind of – only you click the button but not the button label (text of the button). If you click actual text – style does not change.

Weird, but with IE weird is often normal. To alleviate the problem use button HTML element instead of input:

<button type="button" class="mybutton">Click me"</button>

With this markup CSS described above works universally.

Of course if you need to target browser below IE8, CSS selector approach does not work, you have to resort to JavaScript:

<input type="button" style="background-color:white" value="Click Me" onmousedown="this.style.background='green'" onmouseup="this.style.background='white'" />

UltraWebGrid strange behavior in IE8 when IE=EmulateIE7

By , 07/16/2012 4:45 PM

If you’re using Infragistics UltraWebGrid in Internet Explorer 8 you may experience strange visual (and other) issues if you have page compatibility set to emulate IE7, e.g.

<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />

Issues can range from column moving not working to weird distortion in grouped mode. According to Infragistics this combination is not supported as “unstable”, but you can still make it work.

Infragistics keeps internal flags of what browser is currently in use: ig_shared.IsIE7, ig_shared.IsIE8, etc. The trick is to detect IE8 and make it fall back to IE7:

if (ig_shared.IsIE8) {
    ig_shared.IsIE8 = false;
    ig_shared.IsIE7Compat = true;

Place this code on top of your page JavaScript code and when it sees IE8 it will tell grid to use IE7 rendering. This is most definitely a hack, but it works.

UltraWebGrid: “Input string was not in a correct format” error while setting width of a column

By , 07/09/2012 2:37 PM

Infragistics UltraWebGrid allows you to set width of a column in client-side JavaScript, you can do it using code similar to this:


But, while executing this code on the client, you may get a nasty surprise by getting following error from the server:

Input string was not in a correct format.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.FormatException: Input string was not in a correct format.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[FormatException: Input string was not in a correct format.]
System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) +10163939
System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info) +207
Infragistics.WebUI.UltraWebGrid.StateChangeProcessor.ProcessChanges() +6230
Infragistics.WebUI.UltraWebGrid.UltraWebGrid.ProcessChanges(StateChanges stateChanges, Boolean fireEvents) +701
Infragistics.WebUI.UltraWebGrid.UltraWebGrid.LoadPostData(String postDataKey, NameValueCollection values) +7580
System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad) +945
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2071

Now, you do know that your someValue is definitely a number, why this error then? Let alone – why client-size resize causes a server call? But I will leave this to Infragistics. Actual cause of the error – number not being Integer. If you change the code from above to


it will execute without any errors. Go figure.

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