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sessionState="StateServer"

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Jeff asked on 29 Jan 2009, 10:52 PM

I posted a couple of weeks ago about a "No Parameterless constructor" error I was getting:

http://www.telerik.com/community/forums/reporting/telerik-reporting/no-parameterless-constructor.aspx

I was referred to a thread:

http://www.telerik.com/community/forums/reporting/telerik-reporting/binding-to-an-arraylist.aspx

On searching, I found a couple more:

http://www.telerik.com/community/forums/reporting/telerik-reporting/error-messages.aspx

http://www.telerik.com/community/forums/reporting/telerik-reporting/instance-variables-are-lost-when-using-stateserver-as-session-state-provider.aspx

http://www.telerik.com/community/forums/reporting/telerik-reporting/instance-variables-are-lost-when-using-stateserver-as-session-state-provider.aspx

The core of the problem is that when sessionState mode='StateServer' or mode='SqlServer' or mode='Custom', the Telerik reporting engine serializes the report, and then deserializes it using the derived class's parameterless constructor.

Now for us, using mode='inProc' is not an option. I've got no great objection to passing the parameters to the derived report class in some other way. But I'm at a loss as to what other way we can use.

We have a button click event on the page. In it, we construct an instance of the derived report class, passing parameters to the constructor, and assign that object to ReportViewer.Report. It does it's business, and the next time I'm in my own code is in the parameterless constructor of the derived report class. But how do I access the parameters I used when I called the other constructor?

I can't save them in member variables, because they aren't being saved and restored during serialization.

I'm not in a Page, so I have no access to Session. (I thought for a moment that I might be able to access the page, through Report.Container, but it's null.)

So next, I thought that adding them to Report.ReportParameters. But they're not being restored, either.

So where do I store them, so that I can restore them at the appropriate time?

16 Answers, 1 is accepted

answered on 30 Jan 2009, 11:52 AM

Hi Jeff,

As described in the threads you referenced, when you use an OutProc session state mode (SQLServer, StateServer), the Web report viewer would only store the report’s type in the ASP.NET session. This unfortunately leads to some unpleasant limitations:

The report class should have a default constructor.
It is impossible to use a constructor with parameters to customize the report.
All modifications to the report instance made outside the default constructor of the report are lost.

Unfortunately there is no easy workaround and as explained in this thread, we are already working on a solution for Q1.

Please excuse us for the inconvenience.

Greetings,
Steve
the Telerik team

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answered on 30 Jan 2009, 01:57 PM

Is there some way to hook into the event chain after the report has been constructed using the default constructor, so as to restore the state that has been lost?

I tried restoring the state in Page_PreRender(), but that was still too early - the deserialization and the call to the default constructor happened afterward. I'm not aware of any mechanism for inserting code into the page after Page_PreRender, but I thought I'd ask.

At this point, it sounds like we're forced to use InProc, and hope that you can get a fix out before our site grows to where it will need clustered servers. Or we find another report-generating tool.

answered on 30 Jan 2009, 06:14 PM

OK, I knew there had to be a work-around for this.

You can access the session from HttpContext.Current, and store and retrieve parameters from the session.

I've only started to play around with this, but it seems to be working. If there are scenarios where this wouldn't work, please let me know.

The skeleton of an example, without any kind of error checking or handling:

    
            public partial class ReportPage: System.Web.UI.Page 
        
            { 
        
               ... 
        
               protected void btnRun_Click(object sender, EventArgs e) 
        
               { 
        
                  ReportViewer.Report = new TestReport(dropdownList.SelectedValue); 
        
               } 
        
            } 
        
            partial class TestReport 
        
            { 
        
               #region Component Designer generated code 
        
               ... 
        
               #endregion 
        
               private Telerik.Reporting.TextBox txtContents; 
        
            } 
        
            using System.Web; 
        
            using System.Web.SessionState; 
        
            public partial class TestReport : Telerik.Reporting.Report 
        
            { 
        
               public TestReport(string reportParameter) 
        
               { 
        
                  HttpSessionState session = HttpContext.Current.Session; 
        
                  if (session.Mode == SessionStateMode.InProc) 
        
                     generateReport(reportParameter); 
        
                  else 
        
                      session.Add("TestReport_parameter", reportParameter); 
        
               } 
        
               public TestReport() 
        
               { 
        
                  HttpSessionState session = HttpContext.Current.Session; 
        
                  string reportParameter = (string)session["TestReport_parameter"]; 
        
                  generateReport(reportParameter); 
        
               } 
        
               private void generateReport(string parameter) 
        
               { 

                  InitializeComponent(); 
        
                  txtContents.Value = String.Format("The report had a parameter of {0}", parameter); 
        
               } 
        
            }

answered on 29 May 2009, 01:55 PM

Hi Ricardo,

We do understand how important performance with large amounts of data is, and I can assure you that we are working constantly in this direction. We nevertheless have to keep in mind that handling large reports usually requires additional resources in terms of powerful CPUs, and enough memory to handle all the operations. As far as the processing time and consumed memory is concerned, the complexity of the report layout, the complexity of the data calculations (aggregates, conditional formatting), the rendering media, the size of the generated document (in pages), and the capabilities of the underlying machine are crucial.
The current version of the reporting tool would experience performance problems with more than 10,000 , but fixing this will require time. We will also have to take into consideration all other feature requests for the product and leverage the benefit that our clients will get from any improvement, be it performance or new functionality. On top of all this, we are playing catch-up with all vendors on the market, who more or less have very similar performance problems.

Here are a few things you can try. We recommend to avoid using PageCount because it requires an additional pass to count all pages before the actual report rendering (i.e. it renders the report in the memory in order to count all pages). Another option is to reconsider the size of the data you need to display at once (by using parameters and/or filters rather than to show all the raw data from the data source). In contrast to Grid controls, where usually a small subset of data records are displayed, the reporting engines need all the data to layout the pages depending on the selected media (output format). So if your main goal is to show this data for web presentation only, we can suggest a web grid control instead, moreover our RadGrid control exposes API for pdf, csv, word, excel exporting.

Best wishes,
Steve
the Telerik team

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sessionState=&quot;StateServer&quot;

16 Answers, 1 is accepted

sessionState="StateServer"