Putting More Information Into Error Page

rbuser

Hello

How can I get more information into my error page descendant?

I am inheriting from TrsWebErrorPage

I want to get the report parameters into the error page and at least a title

I think I may have to put all of this information into an Exception object
but I am hoping there is a better way than that!

Cheers

Paul

rbuser

I also have another problem now

When I use my webmodule within my web tier test application my error page is
created and used

However, when the actual webtier is used, its not used

I still cannot debug the webtier directly

Where in the webmodule do I need to put the line below

wmMain.rsWebtier.ErrorPageClass := TSTCWebtierErrorPage;

I have put it in the initialization section of the web module

Cheers

Paul

nardmoseley

I would use the WebTier.OnCreate event


Correct. Create a descendant of EWebTierError which is defined in
rsExceptions.


We use the Delphi WebDebugger as much as possible. To debug an ISAPI
application or a ASP application, we use CodeSite and its TCP/IP extension -
which enables an application to broadcast messages to the CodeSite
dispatcher (either on the same machine or on another machine).



--
Nard Moseley
Digital Metaphors Corporation
http://www.digital-metaphors.com

rbuser

ok thanks Nard

I will try this out

I was not aware of there being a TCP extension for Codesite!

Do you have any idea why I am getting the problem mentioned in my last post
here? Where the exception page is not coming up from the webtier itself but
does through my test app?

nardmoseley

1. I think I recall that you have to have the professional version of
CodeSite. You can check with their tech support.

2. I do not know why that would occur. Make sure you are copying the new web
app to the appropriate IIS directory - its easy to forget that last step.

rbuser

Hi Nard

I have verified that and its fine????

Cheers

Paul

nardmoseley

I created a simple test here that works with the demo WebDebug and ISAPI
apps.

1. I created a TMyWebErrorPage class that overrides the CreateErrorPage
method

lTemplate.SetVariable('message', '****Test Custom Error Page****' +
ProcessMessage(aException.Message));


2. Implemented the WebModule.OnCreate event-handler

procedure TWebModule1.WebModuleCreate(Sender: TObject);
begin
rsWebTier1.ErrorPageClass := TmyWebErrorPage;
end;

3. Implemented the WebTier.AfterProcessRequest event to raise an exception

procedure TWebModule1.rsWebTier1AfterProcessRequest(aSender,
aContentProvider, aRequest: TObject; aResponse: String);
begin
raise EReportBuilderError.Create('Test Exception Handling');

end;


I used RB 9.03...

rbuser

What does processMessage do Nard?

I am already raising my custom exception, but its being raised in my process
request code

See below

PROCEDURE TwmMain.FillParameters(CONST
objParameters:TSTCReportParameters;CONST strQuery,strContent:String;CONST
objParametersList:TStringList);
var
objParameter: TSTCReportParameter;
cnt: Integer;
arrTemp:strArray;
BEGIN
TrsWebRequestParser.ParseContent(strQuery,objParametersList);
TrsWebRequestParser.ParseContent(strContent,objParametersList);

FOR cnt:=0 TO objParametersList.Count-1 DO
BEGIN
objParameter:=TSTCReportParameter(objParameters.NewItem);

arrTemp:=Split(False,objParametersList[cnt],'=');

TRY
objParameter.Name:=arrTemp[0];
objParameter.Value:=arrTemp[1];
EXCEPT
objParameter.Value:='';
END;
END;
END;

FUNCTION TwmMain.ExtractConnectionString(CONST
objParameters:TSTCReportParameters):String;
VAR
nCustomerID: Integer;
BEGIN
IF objParameters.ParamExists('ConnectionString') THEN
Result:=objParameters.AsObject('ConnectionString').Value
ELSE
BEGIN
nCustomerID:=objParameters.AsInteger('CustomerID');
Result:=ConnectionStringForCustomer(nCustomerID,cInstallDir+'STCREportsWebtier.ini');
END;
END;

PROCEDURE TwmMain.FillDefaultSessionParams(CONST
objParameters:TSTCReportPArameters;CONST objWebRequest:TrsWebRequest);
VAR strContent:String;
objStringList: TStringList;
BEGIN
TRY
strContent:=objParameters.AsString('Content');
EXCEPT
strContent:='';
END;
objWebRequest.SessionParameters['AdditionalParams'].Value:=objParameters.ToXML;
objWebRequest.SessionParameters['ConnectionString'].Value:=ExtractConnectionString(objParameters);
objWebRequest.SessionParameters['ReportID'].Value :=
objParameters.AsInteger('ReportID');

IF strContent='' THEN
objWebRequest.ContentType:='Viewer'
ELSE
objWebRequest.ContentType:=strContent;

objWebRequest.ReportName:='\'+RBSectionName(TReportID(objWebRequest.SessionParameters['ReportID'].Value))+'\'+RBReportName(TReportID(objWebRequest.SessionParameters['ReportID'].Value));
objWebRequest.VolumeName:='STC Reports';
END;

FUNCTION TwmMain.ProcessRequest(CONST
strQueryString,strContent:String):String;
var
nReportID: Integer;
strTitle: STRING;
objTempParameters: TSTCReportParameters;
objWebRequest: TrsWebRequest;
objParametersList:TStringList;
begin
wmMain.rsWebTier.ErrorPageClass:=TSTCWebTierErrorPage;
TRY
objParametersList:=TStringList.Create;
TRY
objTempParameters:=TSTCReportParameters.Create;
TRY
FillParameters(objTempParameters,strQueryString,strContent,objParametersList);
TRY

nReportID:=objTempParameters.AsInteger('ReportID');

objWebRequest:=rsWebTier.CreateWebRequest(objParametersList,strContent);

FillDefaultSessionParams(objTempParameters,objWebRequest);

Result:=rsWebTier.ProcessWebRequest(objWebRequest);
FINALLY
objWebRequest.Free;
END;
FINALLY
FreeAndNil(objTempParameters);
END;
FINALLY
FreeAndNil(objParametersList);
END;
EXCEPT
ON E:Exception DO
Result:=rsWebTier.HandleException(objWebRequest,
EWebtierException.Create('Title','Additonal Info',E.Message));
END;
end;

nardmoseley

1. Rather than

wmMain.rsWebTier.ErrorPageClass:=TSTCWebTierErrorPage;

try

rsWebTier.ErrorPageClass := TSTCWebTierErrorPage;

2. Try moving the code in 1 above to the WebModule.OnCreate event. That is
what I did in my example.

3. I just copied that method from the ancestor and it was calling
ProcessMessage to perform some formatting. Its not relevant to the example.
You can return any valid html page.

rbuser

Hi Nard

I am getting a problem here

When I step into my code I expect the classname of E to by EWebtierException
but it is EClientError?

My code is below

class function TSTCWebTierErrorPage.CreateErrorPage(
aException: Exception): String;
VAR
objWebTierException:EWebTierException ABSOLUTE aException;
strHTML: STRING;
begin
strHTML:=cErrorHTML;
strHTML:=StringReplace(strHTML,'%Message%',objWebTierException.Message,[rfReplaceAll,rfIgnoreCase]);
strHTML:=StringReplace(strHTML,'%Title%',objWebTierException.Title,[rfReplaceAll,rfIgnoreCase]);
strHTML:=StringReplace(strHTML,'%AdditionalInfo%',objWebTierException.AdditionalInfo,[rfReplaceAll,rfIgnoreCase]);

Result:=strHTML;
end;


FUNCTION TwmMain.ProcessRequest(CONST
strQueryString,strContent:String):String;
var
nReportID: Integer;
strTitle: STRING;
objTempParameters: TSTCReportParameters;
objWebRequest: TrsWebRequest;
objParametersList:TStringList;
begin
wmMain.rsWebTier.ErrorPageClass:=TSTCWebTierErrorPage;
TRY
objParametersList:=TStringList.Create;
TRY
objTempParameters:=TSTCReportParameters.Create;
TRY
FillParameters(objTempParameters,strQueryString,strContent,objParametersList);
TRY

nReportID:=objTempParameters.AsInteger('ReportID');

objWebRequest:=rsWebTier.CreateWebRequest(objParametersList,strContent);

FillDefaultSessionParams(objTempParameters,objWebRequest);

Result:=rsWebTier.ProcessWebRequest(objWebRequest);
FINALLY
objWebRequest.Free;
END;
FINALLY
FreeAndNil(objTempParameters);
END;
FINALLY
FreeAndNil(objParametersList);
END;
EXCEPT
ON E:Exception DO
Result:=rsWebTier.HandleException(objWebRequest,
EWebtierException.Create(RBReportName(TReportID(nReportID)),objTempParameters.AsCommaText,E.Message));
END;
end;

nardmoseley

The custom error page class will be called for all exceptions that occur. Do
not assume that it is of a particular Exception type. Instead check the type
inside you method:

Example:

if (aException is EWebTierException) then
{custom code here}
else
{other custom code here}

rbuser

Hi Nard

I dont quite get this - my code swallows any exception raised and re raises
it as a EWebTierException

How can a EClientError get through this?

One of the ones I am trying out is the classic cannot connect to server

TRY
.................
All code here
EXCEPT
ON E:Exception DO
RAISE
EWebtierException.Create(RBReportName(TReportID(nReportID)),objTempParameters.AsCommaText,E.Message);
END;

Cheers

Paul

nardmoseley

To customize an error page, you need to create a custom error page class -
as we have dicussed.

The WebTier catches all exceptions and calls its HandleException method.
Thus your attempts to trap errors outside of the webtier will not work.


try
{}

except
on E: Exception do
Result := HandleException(CurrentRequest, E);

end;


The HandleException method uses the ErrorPageClass to generate the html
error page. It basically looks like this....



function TrsWebTier.HandleException(aRequest: TrsWebRequest; E: Exception):
String;
begin

Result := GetErrorPageClass.CreateErrorPage(E);
gWebLog.WriteException(E, aRequest.RequestID, aRequest.SessionID);



end;

rbuser

Hi Nard

I have created this class and it works as discussed

My problem is that I specifically raise an EWebTierException - because I
want 2 more pieces of information, however the exception type is not
EWebTier Exception

I have modified the code to raise an EWebTierException it still does not
work!

Cheers

Paul

rbuser

I need to get custom information into my error page class - hence why we
spoke about creating a custom error exception

Am not sure what you mean by me trying to trap errors outside of the webtier

nardmoseley

Where in your code are you raising the exception?


If you want to create a simple test case and email to
support@digital-metaphors.com we can look at it here.

rbuser

ok Nard I have sent you an example

nardmoseley

> ok Nard I have sent you an example

I looked at the example you sent and it is exactly the situation that I
tried to describe before. Sorry if I was not clear before. I will give it
another try.

The problem here is that once you call WebTier.ProcessWebRequest, any
exception that occurs will be handled internally by the web tier and will
result in an HTML Error Page being returned.

Your code looks something like this:

try
Result := myWebTier.ProcessWebRequest(myWebRequest);

except
on E: Exception do
raise myWebException.Create('Custom Title', Custom Info', E);

end;


Your except block will never fired, because the WebTier will catch it first.


If you want to include custom information in the HTML Error Page you will
have to do it by some other means. Perhaps initialize some global variables
prior to calling WebTier.ProcessRequest. Then use the global variables in
the error page class.