I am facing a problem with the Font property of my Composite Custom Web Control.

I have built a composite control with textboxes, labels and buttons.

Following are the code and the error details:

 


    Private _loginidlabelfont As Font 


    


    'Other code 





    Public Property LoginIdLabelFont() As Font 


      Get 


        Return _loginidlabelfont 


      End Get 


      Set(ByVal Value As Font) 


        _loginidlabelfont = Value 


      End Set 


    End Property 





    'Other code 





    Protected Overrides Sub CreateChildControls() 





    'Other Code 


      Dim lblLoginId As New Label() 


      lblLoginId.Text = _loginidlabel 


      lblLoginId.BackColor = _labelbackcolor 


      lblLoginId.ForeColor = _labelforecolor 


      lblLoginId.Font.Name = _loginidlabelfont.Name 





      lblLoginId.Font.Bold = _loginidlabelfont.Bold 


      lblLoginId.Font.Italic = _loginidlabelfont.Italic 


      lblLoginId.Font.Underline = _loginidlabelfont.Underline 


      lblLoginId.Font.Size = convertfont.Point(_loginidlabelfont.Size) 


     


    'Other Code 

Now I am using the composite control in a Web Application.
In the property sheet for the control I get the LoginIdLabelFont() property.
The problem comes when I select multiple styles (Bold, Underline, Italic, Strikeout).
If I select only one of them, it works fine. But, If I select any 2 or more then it gives me an error message:

-----------------------------------------------------------------------------
Object reference not set to an instance of an object.

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.NullReferenceException: Object reference not set to an instance of an object.

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.
-----------------------------------------------------------------------------

Can anybody help me with this?

BR,
Bans.

Can you give us the source line of error?

---

-- Justin Lovell

Can you post your property declarations for these as well? I suspect what is happening is that your setting a font property for one of your child controls and it doesn't have the correctly mapped field to it.... Check your mappings back to your field declarations carefully. You will probably find one that maps back to another controls font properties that isn't ever initialized.

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Answering a question increases your knowledge asking a question shows your Intelligence!

Justin:

Its surprising but its not giving any line number... I am getting this error when I am executing my Web Application, which contains nothing else but this Composite Control.

Fancy:

Below are the Property declarations for the other properties, but, the problem I am facing only when I am specifying two or more styles (Bold, Italic, Underline & Strikeout) in the Web Application where I am using this Composite Control.

          Private _labelbackcolor As Color


          Private _loginidlabel As String


          Private _labelforecolor As Color








        Public Property LoginIdLabelText() As String


            Get


                Return _loginidlabel


            End Get


            Set(ByVal Value As String)


                _loginidlabel = Value


            End Set


        End Property





        Public Property LabelForeColor() As Color


            Get


                Return _labelforecolor


            End Get


            Set(ByVal Value As Color)


                _labelforecolor = Value


            End Set


        End Property





        Public Property LabelBackColor() As Color


            Get


                Return _labelbackcolor


            End Get


            Set(ByVal Value As Color)


                _labelbackcolor = Value


            End Set


        End Property

Is there a way to specify each part of the Font property(Style, Color, Size, etc) individually??

BR,
Bans

:: I suspect what is happening is that your setting a font property for one of your child controls and it doesn't have the correctly mapped field to it....

If it was throwing an exception to that, it would throw a syntax error and it will give you a line problem. Because it is not giving the source line of the error, either of the two are happening:

1) Your user control is compiled into release mode by ASP.NET (configured on the Page declaration or alternatively in the web.config for site wide configuration).

2) The error is being thrown out of your scope of the user control. If it is this, then the stack trace will become extremely *valuable*.

The easiest to check first with the first one. If it is this, switch on debugging and tell ASP.NET to compile into "debug" mode. That is the fastest as well. However, I suspect it is alternative two but without the first step, I cannot say for sure if it is an error that is happening internally.

---

-- Justin Lovell

Justin,

The first case is not true... The user control has been compiled in the Debug mode itself.

Bans

Ok, starting to fall into place. Can you give the stack trace of the error?

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-- Justin Lovell

Bans I am going to take a guess here and say that asp.net server controls are not able to work with the system.drawing.font object in the way that your trying to use it. It would be interesting to see how that acts in a winform. If the inherited property "Font" that comes from webcontrol isn't going to work for you then I suggest just allowing for a Font name then create bool drop downs for the styles. I have played with the system.drawing.font object in the property browser before and I am not sure if that is a bug or if it works as designed. But I do know that no matter what you do your going to get an error if you pick more than one font-style. If you figure it out I would be glad to hear about how you got around it. Only thing I can think of is to just use it in a way to persist some code to the Initialization() while in design-mode that you could come back and use at runtime. Because embedding that font information into an html tag is going to generate and error if more than one style is chosen.

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Answering a question increases your knowledge asking a question shows your Intelligence!

Here is the Rest of the error message:

Stack Trace:


[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.Compilation.CodeDomUtility.GenerateExpressionForValue(PropertyInfo propertyInfo, Object value, Type valueType) +2171
System.Web.Compilation.CodeDomUtility.GenerateExpressionForValue(PropertyInfo propertyInfo, Object value, Type valueType) +1213
System.Web.Compilation.CodeDomUtility.GenerateExpressionForValue(PropertyInfo propertyInfo, Object value, Type valueType) +1503
System.Web.Compilation.TemplateControlCompiler.BuildBuildMethod(ControlBuilder builder, Boolean fTemplate, PropertySetterEntry pse) +2549
System.Web.Compilation.TemplateControlCompiler.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, PropertySetterEntry pse) +794
System.Web.Compilation.TemplateControlCompiler.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, PropertySetterEntry pse) +352
System.Web.Compilation.TemplateControlCompiler.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, PropertySetterEntry pse) +352
System.Web.Compilation.TemplateControlCompiler.BuildMiscClassMembers() +52
System.Web.Compilation.PageCompiler.BuildMiscClassMembers() +10
System.Web.Compilation.BaseCompiler.BuildSourceDataTree() +1276
System.Web.Compilation.BaseCompiler.GetCompiledType() +129
System.Web.UI.PageParser.CompileIntoType() +60
System.Web.UI.TemplateParser.GetParserCacheItemThroughCompilation() +124

[HttpException (0x80004005): Object reference not set to an instance of an object.]
System.Web.UI.TemplateParser.GetParserCacheItemInternal(Boolean fCreateIfNotFound) +692
System.Web.UI.TemplateParser.GetParserCacheItemWithNewConfigPath() +125
System.Web.UI.TemplateParser.GetParserCacheItem() +88
System.Web.UI.TemplateControlParser.CompileAndGetParserCacheItem(String virtualPath, String inputFile, HttpContext context) +116
System.Web.UI.TemplateControlParser.GetCompiledInstance(String virtualPath, String inputFile, HttpContext context) +36
System.Web.UI.PageParser.GetCompiledPageInstanceInternal(String virtualPath, String inputFile, HttpContext context) +43
System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String path) +44
System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, String path, String pathTranslated, Boolean useAppConfig) +699
System.Web.MapHandlerExecutionStep.System.Web.HttpApplication+IExecutionStep.Execute() +95
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +173




--------------------------------------------------------------------------------
Version Information: Microsoft .NET Framework Version:1.1.4322.573; ASP.NET Version:1.1.4322.573

I am starting to suspect it is an error on your page... the problem is possibly not in the control. Check it out by commenting out the lines in your control. When you are left with almost nothing, you will know that the problem is on the page.

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-- Justin Lovell

The problem is in serializing of the html. When you implement it the way you have it serializes the html attributes of the font into the tag of your control... which is fine and dandy with the exception that it should not serialize the property itself just the sub-properties. Try it! Set 2-3 sub-properties but then go back to html view and take out the property itself but leave the sub-properties and you will see it works fine, for the life of me I have never figured out how to do it (just serialize sub-properties). That?s how the Font property works in the property browser it serializes just sub-properties but not the Font property itself. You do have to set [DesignerSerializationVisibilityAttribute(DesignerSerializationVisibility.Content)] on the property to get the sub properties serialized but the problem is it still serializes the parent also.

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Answering a question increases your knowledge asking a question shows your Intelligence!

Justin:

Do you want me to comment out just the 'Protected Overrides Sub CreateChildControls()' Sub procedure or the whole code of the control (the property declaration, etc)??

If I comment the property declarations then I wont get the error. On commenting just the 'Protected Overrides Sub CreateChildControls()' sub procedure I am getting the same error.

Fancy:

I am afraid, I am very new to .Net - I dont know how to Serialize the property...
Please help me with an example...

Thanks,
Bans

Ok, why don't you drill down to a specific block of code. You know that you are having troubles with the properties... so drill down which propert(y/ies) are giving the hassle. For some gut feeling, I do not think that the null value is accepted.

Otherwise, I would like to know how you are setting the values? Also, I would like to know the source file name that is throwing the error? (it is found between the stack trace and the source line).

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-- Justin Lovell