share procedures and function with a postgresql connection
lazarus / 16-Databases

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aviatorz · 2012-11-28 18:55

i am trying to make a class with only procedures and functions, some
procedures need use a postgresql connection, for example.

Code: [Select]...
class var
      {Variables de clases}
      SQLquery:TSQLQuery;
      Datasource:TDataSource;
      Transaccion:TSQLTransaction;
      PQConexion:TPQConnection; 
...
class procedure
StaticData.Inicializa_conexion(usuario,contrasena,host,db:string);
begin
     PQConexion.hostname:=host;
     PQConexion.databaseName:=db;
     PQConexion.username:=usuario;
     PQConexion.password:=contrasena;

     PQConexion.transaction:= Transaccion;
     Transaccion.DataBase:=PQConexion;
     SQLQuery.Transaction:=Transaccion;
     Datasource.DataSet:=SQLQuery;

     try
        PQConexion.connected:=true;
        Application.MessageBox(PChar('Conexion realizada con
exito'),PChar('Conexion'),MB_ICONINFORMATION);
     except
       on e:exception do
       begin
         Application.MessageBox(PChar('Ha ocurrido el siguiente Error:
'+e.Message),PChar('Error'),MB_ICONINFORMATION);
         PQConexion.connected:=false;
       end;
     end;
end;

The problem is when i try to set a property of PQConexion, i see this
error.

Code: [Select]El proyecto X ha lanzado una excepcion de la clase
'External:SIGSEGV'. en direccion 403AD0
The error is when i try to put a value to a property of PQConexion
Code: [Select]PQConexion.hostname:=host;

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Blaazen · 2012-11-28 18:59

Hello,
Where do you call constructor ?
Code: [Select]PQConexion:=TPQConnection.Create;

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aviatorz · 2012-11-28 19:05

Quote from: Blaazen on November 28, 2012, 07:59:56 pmHello,
Where do you call constructor ?
Code: [Select]PQConexion:=TPQConnection.Create;

I tried that and i got
Code: [Select]staticclase.pas(36,38) Error: Wrong number of parameters
specified for call to "Create"
staticclase.pas(68) Fatal: There were 1 errors compiling module,
stopping
But i put
Code: [Select]PQConexion:=TPQConnection.Create(Application);
and now the problem is solved, but is this correct?

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Blaazen · 2012-11-28 19:13

You have to call constructor before you use the PQConnection. No
matter if it is global, local or class variable. In this case, good
place can be initialization section. If it works then it's correct.