Save XML file from database to hard disk

[mark]

Hi,

I have problem with saving XML files from postgresql 12.x database to hard drive (XML data type field). I have working procedure with blob data type (binary):

Code: Select all

var
 blob,myFileStream:TStream;
 SaveFile:string;
begin
 SaveFile:='c:\test\test.xml';
   blob := Zquery.CreateBlobStream(Zquery.FieldByName('xml_file'), bmRead);
   try
    blob.Seek(0, soFromBeginning);
    myFileStream := TFileStream.Create(SaveFile, fmCreate);
    try
     myFileStream.CopyFrom(blob, blob.Size) ;
    finally
     myFileStream.Free ;
    end;
   finally
    blob.Free ;
   end;
end;

This procedure works well with binary data type but when i use xml data type i have empty stream and file. How to save XML files to hard drive?

Regards
Mark

[Fr0sT]

My guess (haven't worked with Pg): is Pg XML type really supported? It looks like a custom one. Probably it needs special handling

[miab3]

Hi,

You can use ::xml

Michal

[aehimself]

For a really long time now, I switched storing everything (even Strings, if they are coming from an "outside" source - like HTTP requests, files what the user might edit) as TBytes (in Delphi, that's equivalent to Array Of Byte). That way I can do all kind of manipulation before storing it in it's final variable.

I don't have Lazarus / FPC, but this is really easy to be converted if necessary. And works like a charm, on all data types (not just blobs!).

Code: Select all

Uses System.SysUtils, System.IOUtils;

Var
 tb: TBytes;
Begin
 tb := SQLQuery.FieldByName('something').AsBytes;
 TFile.WriteAllBytes('C:\rawdump.bin', tb);
End;