crystal viewer parameter loses value on navigation

[cecilia_schultz]

Using "SAP Crystal Reports runtime engine for .NET Framework (64-bit)" version 13.0.31.4010,

and the corresponding component for VS: "SAP Crystal Reports, version for Microsoft Visual Studio" version 13.0.31.4010.

The CR viewer is CrystalDecisions.Web, Version=13.0.4000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304

My report has several string type parameters. One of these parameters (called p_stu_cnt) is passed to the report. This param is displayed in the 2nd page header of the report.

When the report is rendered, it shows its value fine (e.g. "100"), but when I navigate (say, go to the next page), the parameter loses its value in the report (shows "0").

Not surprisingly, if I export, say to PDF, the lost value appears int he exported output.

I found an article https://community.sap.com/t5/technology-q-a/navigation-in-crystal-viewer-with-parameters/qaq-p/10016... that suggested setting the ReuseParameterValuesOnRefresh property of the viewer to true (it was false by default). I have done this, but no luck resolving the issue.

The value of this parameter is passed from a string variable, which is prior set to the given dataset's table row count, i.e.

string mQualifyingStudentCount = dtResults.Rows.Count;

then later passed on to the report parameter like so:

string p_stu_cnt = mQualifyingStudentCount.ToString();
report.SetParameterValue("p_stu_cnt", p_stu_cnt);

The strange thing is that if I just hardcode of my variable and pass it on to the report param, then the value is not lost! i.e:

string p_stu_cnt = '123";
report.SetParameterValue("p_stu_cnt", p_stu_cnt);

Is this a bug??!!

I appreciate your help,

[cecilia_schultz]

I was not able to see find known bugs. Can you please refer me to that posting? if this is a bug, it is extremely weird: what does it matter to the viewer how I get the value passed in to the parameter? whether I hardcode it, or whether I obtained it from the associated datatable row count, what does it matter? it is still put into a variable, which then used to pass to the parameter value! so why hardcoding the variable value or not would make a difference??

[cecilia_schultz]

Don, regarding "No Idea what the report key is you mentioned", this is what I am referring to: the code in the article you referred me to, has this line (in the butReport_Click method): Session.Add(“Report”, crReportDocument); therefore, the code is saving the report document in the session under the "Report" key. My question was, is this key name specifically required? are you telling me that the cr viewer will look in the session with this key?

[cecilia_schultz]

Don, I was able to implement the saving of the report in the session and add the code looking at the postback. All works *almost* perfectly now (yeah! Thank you!), meaning no more losing of the param value on navigation, no "please wait" spinning either and can export fine (these were also an issue) . The onyl problem now is that when i re-runt he report with a different parameter (obtained from the web form input at runtime) the first time is ok, but the 2nd time choosing a different value, it is not going thru the showReport() where all happens when it is the first time. The reason is that the report was saved in the session, but it has not been removed on Page_Unload()! On Page_Unload(), I am only doing report.Close(); report.Dispose(); but this does not remove the report from the session. Not surprisingly, when i re-run the report a second time, it still uses the first value from the session (which is old, fromt he first time it ran). I have added a sess.Remove("Report"); to the Page_Unload method. Let me try, I think that should do the trick

[cecilia_schultz]

Don, please see my previous posting ('*almost* perfectly): Now, when I added the line in Page_Unload() to remove the report from the session (Session.Remove("Report")), now I get a prompt from Crystal "Enter Values" when i try to go to the next page. It says "The report you requested requires further information" and asks me for Server name, User name and Password. Why??

[cecilia_schultz]

Don, I restructured all in one single page just to closely resemble the KBA for another, as well as made as very simple bare bones as possible to make it simple. Still, as said before, the user input is taken programatically by the web form and then used to set the report parameter accordingly. I have gave i another try, this time with CrystalReportViewer1.EnableParameterPrompt = true as you said. The first time the report is run, say the inpout is 100, which is used to generate the dataset accoridngly, and to set the param to the report. The report renders fine , and you can see it used the 100 param. when clicking next page in the report, the "please wait while the document is being processed" spinning wheel appears forever. One has to close the browser. The report is actually very simple, but has a lot of rows (~77K). I am going to use NPOI instead since CR viewer is not working for me in this case. Thank you.

[cecilia_schultz]

Here is the entire code, very much simplified as said before (Now pasting pics as I don't see the "more" button or "C#" option)

[cecilia_schultz]

Sorry, the "more button" where? I am writing this in the field alongside the "commnet" button, and I don't see a "more" button, or any button other than the "comment" button.

[cecilia_schultz]

Don, I found an "Edit Comment" from the down-arrow drop down. This takes me to an editing window with varios tools. I still don;t see "more" or "C#", but I found a "insert photo", so I replaced the unreadable code with pics of my code (since i don't see a way to upload the C# code).

[DonWilliams · Accepted solution]

This happens in a WEB app if you don't use sessions and postback:

1985571 - How to use sessions in web applications using the Crystal Reports viewer (the complete cod...

See if that resolves the issue.

If it's a desktop app then likely you are using Refresh() in your code which will remove the current values.

Oh and I suggest updating to SP 36, CR for VS is only supported in the latest SP, SP 31 had issues in the viewer:

https://help.sap.com/docs/SUPPORT_CONTENT/crystalreports/3354091173.html

[cecilia_schultz · Accepted solution]

Hello Don, Thank you very much for the quick response. Article 1985571 you referred me to does not seem to be complete: what is the RAPPBasePage class the class "Reports" int he code is inheriting from? Also, the code int he article is saving crReportDocument in the session under the "Report" key. Is this key name specifically required? are you telling me that the cr viewer will look in the session with this key?

[DonWilliams · Accepted solution]

RAPPBasePage is your application, loading the report using a session and the postback keeps the report in session so it doesn't lose the parameters. No Idea what the report key is you mentioned

[DonWilliams]

[DonWilliams]

The sample I created in the KBA works perfectly.

What you need to do is think about your work flow...

For example, if you close the session the report is no longer valid so you have to go through the whole routine again including logging onto the data source and parameters. If all you want to do is change the parameter value passed then EnableParameterPrompt in the Viewer, the user will then see a Parameter box on the left side which they'll be able to refresh and choose a new value.

[cecilia_schultz]

Don, thank you very much for the assiatnce, but unfortunately, the previous version that I thought it was "good" was not complete. First, I had forgotten to clear the report from memory (report.Close() report.Dispose()). Second, because the code does not go thru the entire thing (loading the report, generating the data, setting the parameters, and finally saving the report in the session), when IsPostBack is true, it causes that a second time the report is run (with a different parameter), it has the same exact data, even though the param was different. This is not a workable solution. A different parameter means the dataset will be different. All is passed programatically thru a webform. Additionally I have 2 pages, the first one collects the input (once the user enters the parameter via input in the first page . When this occurs, the flow passes it to a second page where the dataset is generated (based on the given input passed from the previous page), and report rendered. The example provided in the KBA does not have parameters. Nevertheless, when all the process to render the report is byppassed because if the IsPostBack logic, then what you get is old data. This is only evident when you ran the reportt twice with 2 different inputs. Setting EnableParameterPrompt to true is not an option, all the input is already colelcted via a web form, the report parameters are set programatically form this input. Thank you.

[DonWilliams]

EnableParameterPrompt to true allows the Viewer to use a new parameter, otherwise it always uses the same one.

[DonWilliams]

Your code is unreadable, use the more button and sellect paste code and select C#