[SOLVED] Problem with try except
lazarus / 16-Databases

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melwinek · 2015-04-25 08:51

I want to handle the exception of duplicate key.

...............
try
  SQL.ExecSQL;
except
   on E: EDatabaseError do
     ShowMessage(E.Message);
end;

First I get my message from ShowMessage.
Then the standard message:
"PQConnection1: Preparation of query failed.........Press OK to ignore
and risk data corruption. Press Cancel to kill the program."

How to eliminate standard message?

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totya · 2015-04-25 09:18

Code: [Select]try
  SQL.ExecSQL;
except
   on E: EDatabaseError do ShowMessage(E.Message);
   on E: Exception do; // if you want to hide this error message
really...
end;

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LacaK · 2015-04-25 15:43

EPQDatabaseError which is raised by TPQConnection is descendant of
EDatabaseError, so it should be handled by:
  on E: EDatabaseError do

I do not understand why error message is displayed twice:
- first by ShowMessage
- second standard error handling

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Leledumbo · 2015-04-25 16:56

Sample project required. Exception that has been handled won't return.
i.e. if EDatabaseError (or its descendants) is raised by ExecSQL and
handled by on e: EDatabaseError, then after that, normal program flow
continues. The second one must be triggered by another thing, could be
the same method, I don't know as I can't see the complete code.

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melwinek · 2015-04-28 09:24

Quote from: totya on April 25, 2015, 11:18:46 amCode: [Select]try
  SQL.ExecSQL;
except
   on E: EDatabaseError do ShowMessage(E.Message);
   on E: Exception do; // if you want to hide this error message
really...
end;

Thank you very much.
It works.