I'm here again to ask for a help to you. This time I believe that few will respond given the great particularity of the problem which I will relate. I'm starting in the world of DataSnap, and still have things I do not understand how this error I will relate.
My Delphi is XE (version 1, Update1). I am using Postgres which generates error messages in Portuguese (Portuguese Brazil) and for this reason the error messages have accents. The connection components are ZeosLib package.
I am using a dialog box "reconcile error" to display errors arising from the application of updates and to test, I tried to insert a record that already existed, thus violating a unique key and thus displaying the reconcile error dialog.
In the memo of the dialog, the message that appears is truncated, ie cut. Check it out:
ERRO: duplicar valor da chave viola a restrição de unicidade "uc_usu_va_login"
DETAIL: Chave (va_login)=(admin) já existe.
CONTEXT: comando SQL "INSERT INTO USUARIOS (VA_NOME
,VA_LOGIN
,CH
But actually what should be returned is this:
ERRO: duplicar valor da chave viola a restrição de unicidade "uc_usu_va_login"
DETAIL: Chave (va_login)=(admin) já existe.
CONTEXT: comando SQL "INSERT INTO USUARIOS (VA_NOME
,VA_LOGIN
,CH_SENHA
,VA_EMAIL)
VALUES (pVA_NOME
,pVA_LOGIN
,pCH_SENHA
,pVA_EMAIL)"
PL/pgSQL function "idu_usuarios" line 7 at comando SQL
I have done a debug on the server to see if the problem is ZeosLib, but I found that the error message generated on the server is complete, proving that ZeosLib does not truncate the message. Everything is unicode. All strings are WideString (the default) on both my program and in ZeosLib.
As you know, to be thrown on the server, the exception is forwarded to the client, roughly speaking, by DataSnap, and on the client, the Reconcile method of TClientDataSet verify if there were problems and then throw the famous exception EReconcileError that can be handled in the OnReconcileError event of TClientDataSet, therefore I believe that the message is being truncated by DataSnap.
On the client I debug the Reconcile method (DBClient.pas) and immediately before the exception is thrown the flow enters a function within a cpp source code that I think part of the library midas.dll, MidasLib.obj more specifically, since I am using this strategy, not to have to distribute the DLL with my application.
Check(FDSBase.Reconcile_MD(FReconcileDataSet.FDSBase, FDeltaPacket, VarToDataPacket(Results), Integer(Self), RCB));
This call is done at line 1952 of the unit DBClient.pas on Delphi XE Update1. Pressing F7, the debugger enters a source C++ (cpp), so I believe it is within the midaslib.obj. How I do not understand C++ well, I press Shift-F8 to exit the current method and return the next instruction, that is already inside the event OnReconcileError!! Therefore, the truncation must be done within the function I mentioned, within a cpp source, within midaslib.
My intention is to make the Reconcile Error dialog a tool not only for the final user but to support personals, providing separately information of Error, Details and Context. This helps a lot to discover a problem.
The problem now is to make the message appear in full. Has anyone had this kind of problem with messages being truncated by midas?
Also another point DSClient.pas I could extract the error message as it is passed to the exception:
'Erro SQL: ERRO: duplicar valor da chave viola a restrição de unicidade "uc_usu_va_login"'#$A'DETAIL: Chave (va_login)=(admin) já existe.'#$A'CONTEXT: comando SQL "INSERT INTO USUARIOS (VA_NOME'#$A' ,VA_LOGIN'#$A' ,CH'
If you remove the quotes and replace #$A (1 character) by a white space (one character), you will see that the string has exactly 255 characters!!
I also discovered that the "GetErrorString" in dspickle.cpp uses the constant DBIMAXMSGLEN which is defined in bdetypes.h as 127 (half of 255). As we are in the world of Unicode, it would not be a question of increasing this value to 255 in order to have two bytes per character? This is only a guess...
I leave the question in the air because I lack the knowledge to understand C++ :) Who can help, just look at the function implementation "GetErrorString" in dspickle.cpp. There is this:
LoadString((HINSTANCE)hDll, iErrCode, pString, DBIMAXMSGLEN)
pString is the error message and DBIMAXMSGLEN = 127.