mORMot Open Source

cvpas

Member

Registered: 2018-09-28

Posts: 1

Delphi/FPC difference for string properties without index specifier

Hi,

  For reporting purposes I need to load some JSON content into a TDataset descendant.
So I tried to use JSONTableToDataSet function from mORMotVCL unit as below
(notice that TSQLRecordPerson.LastName property is declared without an index specifier):

program str_prop_indx;

{$IFDEF FPC}
  {$MODE DELPHI}
{$ELSE}
  {$APPTYPE CONSOLE}
{$ENDIF}

uses
  SysUtils, SynCommons, mORMot, mORMotVCL;

type
  TSQLRecordPerson = class(TSQLRecord)
  private
    FFirstName: RawUTF8;
    FLastName: RawUTF8;
  published
    // with index specifier
    property FirstName: RawUTF8 index 30 read FFirstName write FFirstName;

    // with NO index specifier
    property LastName: RawUTF8 read FLastName write FLastName;
  end;

var
  lJSONStr: RawUTF8;
  lSynSQLTableDS: TSynSQLTableDataSet;
  lSQLTableJSON: TSQLTableJSON;
begin
  lJSONStr := '[{"FirstName":"John", "LastName":"Doe"},{"FirstName":"Mark", "LastName":"Twain"}]';

  lSynSQLTableDS := mORMotVCL.JSONTableToDataSet(nil, lJSONStr, [TSQLRecordPerson]);
  try
    lSynSQLTableDS.First;
    while not lSynSQLTableDS.Eof do
    begin
      Write(' FirstName="' + lSynSQLTableDS.FieldByName('FirstName').AsString + '"');
      Write(' LastName="' + lSynSQLTableDS.FieldByName('LastName').AsString + '"');
      WriteLn;
      lSynSQLTableDS.Next;
    end;
    Writeln('RecordCount=' + IntToStr(lSynSQLTableDS.RecordCount));
    Write(' FirstName DataSize=', lSynSQLTableDS.FieldByName('FirstName').DataSize);
    Write('   LastName DataSize=', lSynSQLTableDS.FieldByName('LastName').DataSize);
    WriteLn;
  finally
    lSynSQLTableDS.Free;
  end;
  WriteLn('Press Enter to exit ...');
  ReadLn;
end.

Delphi 7 output is:

 FirstName="John" LastName="Doe"
 FirstName="Mark" LastName="Twain"
RecordCount=2
 FirstName DataSize=31   LastName DataSize=6
Press Enter to exit ...

FPC output is:

 FirstName="John" LastName="D"
 FirstName="Mark" LastName="T"
RecordCount=2
 FirstName DataSize=31   LastName DataSize=2
Press Enter to exit ...

  In case of FPC the content of the LastName field is truncated to 1 character.
  During the JSONTableToDataSet call the JSON string is loaded into a TSQLTableJSON
and then its content will initialize a TSynSQLTableDataSet.
  I suspect that something goes wrong in the method TSQLTable.FieldLengthMax() but I was unable to find what exactly.

  Can someone look into this.

Thank you