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Save reports to BLOB filed in Firebird

Hello,

I have some code in Delphi 2007 that stores reports in a firebird BLOB binary field.
The same code does work in Delphi 10.4 (no errors, and data is stored), but when I look in a BLOB-editor the data is not correct. A lot of "?????????". And restoring the report is not possible.

The differences are unicode, and the fact the I use Firedac, and not BDE + TSQLQuery

How should I store the data in Delphi 10.4 in such a way the report is readable ?

The code is the following :

procedure TDM_Archief.archive(Filename: string; ID: integer) ;
var
BinFile: TMemoryStream;
Buff: String;
begin

//Create file stream.
BinFile := TMemoryStream.Create;
BinFile.LoadFromFile(Filename);
BinFile.Position := 0; // reset to the beginning of the stream


//Allocate memory for the buffer.
SetLength(Buff, BinFile.Size);

//Read file into buffer.
BinFile.Read(Buff[1], BinFile.Size);

QFaktuurArchiefInsert.ParamByName('ID' ).AsInteger := ID;
QFaktuurArchiefInsert.ParamByName('Bestand' ).AsBlob := buff;

QFaktuurArchiefInsert.ExecSQL;

end;

The insert-query is in essence :

SQL.Strings = INSERT INTO ARCHIEF_FAKTUREN (NUMMER, FAKTUUR) Values ( :ID, :Bestand )

ParamData = <
item
Name = 'ID'
DataType = ftInteger
ParamType = ptInput
end
item
Name = 'Bestand'
DataType = ftBlob
ParamType = ptInput
end>


The BLOB-filed is of subtype 0 (binary)

Any help/hint is very welcome,


kind regards,

Dirk Janssens

Comments

  • edited September 2021
    Hi Dirk,

    One item that stands out in your code is the use of a string to hold the file contents before adding it to the database. Strings in Delphi are Unicode encoded so your data is likely being converted.

    I suggest using a byte array (TBytes) rather than a string for the Buff variable. This is the standard way to operate with binary data in modern versions of Delphi.

    Best Regards,

    Nico Cizik
    Digital Metaphors
    http://www.digital-metaphors.com
  • Hi Nico

    Thank you for your reply. It makes sence, and will probably do the trick,
    but I already found an other solution :

    In stead of

    "QFaktuurArchiefInsert.ParamByName('Bestand' ).AsBlob := buff;"

    I use:

    QFaktuurArchiefInsert.ParamByName('Bestand' ).DataType := ftBlob ;
    QFaktuurArchiefInsert.ParamByName('Bestand' ).AsStream := TFileStream.Create(Bestandsnaam,fmOpenRead);

    Now the data is stored as usual...( and it looks as if this is also faster )

    kind regards,

    Dirk Janssens.
  • Just one more question:
    I now have some useless data in my table. Is it somehow possible to convert the data that is stored as Unicode back to Ansi-string ?
  • Hi Dirk,

    Yes, copying the stream data directly will also avoid any encoding issues and likely be faster than using an interim data structure.

    I'm a bit unclear about your second question. What exactly are you storing to your database? Are these report archive files, templates, or something else? I am unclear what you mean by "useless data" in your table.


    Best Regards,

    Nico Cizik
    Digital Metaphors
    http://www.digital-metaphors.com
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