Saving Pictures to Firebird
lazarus / 16-Databases

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goldfish999 · 2015-02-13 20:58

I have a form with a DBImage component.  I can get a jpeg picture to
load into the component but I cant save it as a blob to the Database.
Please help

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balazsszekely · 2015-02-13 22:39

Firebird? Cool!
You should declare the picture field like this:  BLOB SUB_TYPE 0
SEGMENT SIZE 80

Code: [Select]uses db;
var
  st: TStream;
  JPEG: TJPEGImage;
begin
   JPG := TJPEGImage.Create;
   try
      //load the jpg here
      st := qPicture.CreateBlobStream(qPicture.FieldByName('PICTURE'),
bmWrite);
      JPG.SaveToStream(st);
   finally
     JPG.Free;
   end;
end

You don't have to free st...it will be freed internally.

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goldfish999 · 2015-02-14 05:27

Thanks for that but I have always been afraid to mess with Streams.
This is what I have interpreted your code to:-


procedure TFrmGardenA.BitBtnSavePictureClick(Sender: TObject);
var   st: TStream;
      JPEG:  TJPEGImage;
begin
        JPEG := TJPEGImage.Create;
        try
           //load the jpg here
//           st :=
qPicture.CreateBlobStream(qPicture.FieldByName('PICTURE'), bmWrite);
           st := DM1.ZTableVariety.CreateBlobStream(DM1.ZTableVariety.
FieldByName('PICTURE'), bmWrite);
           JPEG.SaveToStream(st);
        finally
          JPEG.Free;
        end;
end;

I guess I got it wrong because nothing happens. I don't even get an
error message.

Where have I gone wrong.  As you see I don't understand streams
Thanks

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fpcoder · 2015-02-14 05:54

"TStream is the base (abstract) class type for stream objects. Being
abstract means that TStream should never be used as such."

Try TMemoryStream instead.

http://delphi.about.com/od/vclusing/l/aa110803a.htm

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balazsszekely · 2015-02-14 06:58

Hi all,

Quote@kapibara
TStream is the base (abstract) class type for stream objects. Being
abstract means that TStream should never be used as such.
Try TMemoryStream instead.
TStream has a lot of virtual methods, which are implemented in the
child class(Read, Write, Seek, GetPosition, etc). Since you don't want
to access those method, in this particular case TStream will do just
fine, even CreateBlobStream returns a TStream.  But yes, generally
speaking you're right, TStream is indeed an abstract class, so you can
replace it with TBlobStream(TMemoryStream) if you like, but that's not
the reason why the save fails!

QuoteI guess I got it wrong because nothing happens. I don't even get
an error message.
Where have I gone wrong.  As you see I don't understand streams
What is ZTableVariety? A TZTable(Zeos)? You should assign a connection
to it. After you saved the image, post the changes(which is a logical
transaction-->visible to other connections, but not permanently saved
to database).  After the post, call ZConnection1.Commit method to
permanently save the data.
Something like this:
Code: [Select]procedure TFrmGardenA.BitBtnSavePictureClick(Sender:
TObject);
var
   st: TStream;
   JPEG:  TJPEGImage;
begin
    JPEG := TJPEGImage.Create;
    try
       //load the jpg here
       st := DM1.ZTableVariety.CreateBlobStream(DM1.ZTableVariety.Fiel
dByName('PICTURE'), bmWrite);
       JPEG.SaveToStream(st);
    finally
      JPEG.Free;
    end;
    DM1.ZTableVariety.Post; //<--logical transaction
    DM1.ZTableVariety.ApplyUpdates; //<-- some database components
require this line,  I don't know about zeos(I personally never used)
    ZConnection1.Commit; //permanently save the changes
end;

regards,
GetMem

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goldfish999 · 2015-02-14 07:49

Ok tried to do that. Looks like this now.
procedure TFrmGardenA.BitBtnSavePictureClick(Sender: TObject);
var   st: TStream;
      JPEG:  TJPEGImage;
begin
            JPEG := TJPEGImage.Create;
            try
//load the jpg here
                        DM1.ZTableVariety.Edit ;
                        st := DM1.ZTableVariety.CreateBlobStream(DM1.Z
TableVariety.FieldByName('PICTURE'), bmWrite);
                        JPEG.SaveToStream(st);
                DM1.ZTableVariety.Post; //<--logical transaction
                  DM1.ZTableVariety.ApplyUpdates; //<-- some database
components require this line,
                          //I don't know about zeos(I personally never
used)
                  DM1.ZTableVariety.CommitUpdates; //permanently save
the changes        finally
            finally
                        JPEG.Free;
            end;
            JPEG.Free;

end;


Now I get this error:=  Project raised exception class 'External:
SIGSEGV'

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balazsszekely · 2015-02-14 07:57

You free JPEG twice....and please use the code tag.
[ code ]Enter your code here [ /code ]
Just remove the spaces inside [].

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goldfish999 · 2015-02-14 13:02

Ive removed the second ' JPEG.Free' but nothing happens now.  No
Errors but the picture is not saved and the DBImage is cleared and
goes blank.  Im sorry but im not very sure about what ive done wrong

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goldfish999 · 2015-02-14 13:16

ZTableVariety is just a table with the Various Details about a
specific variety of plant (ie name, common name , height etc and I
want to add pictures of the plant

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hallenberger · 2015-02-14 13:18

Hello!

Here is my way to save pictures into a firebird table:

Code: [Select]Type

  { TCBild }

  TCBild = Class(TObject)
  Private
    Fangelegt: Tdatetime;
    Fautor: String;
    Fbstichwort: TStringList;
    Fbstichworttabelle: String;
    Fbtabelle: String;
    Fdatei: Tmemorystream;
    Fid: Int64;
    Ftabstwbild: String;
    Procedure Setangelegt(Const Avalue: Tdatetime);
    Procedure Setautor(Const Avalue: String);
    Procedure Setbstichwort(Const Avalue: TStringList);
    Procedure Setbstichworttabelle(Const Avalue: String);
    Procedure Setbtabelle(Const Avalue: String);
    Procedure Setdatei(Const Avalue: Tmemorystream);
    Procedure Setid(Const Avalue: Int64);
    Procedure Settabstwbild(Const Avalue: String);

  Public
....
    Property Datei: tmemorystream read FDatei write SetDatei;

    Procedure Save2DB;
...
    Constructor Create;
    Destructor Destroy;
      Override;
  End;

Implementation

...

Procedure Tcbild.Save2db;
Var
  Sql: String;
Begin
  Try
    Sql := 'insert into ' + Fbtabelle + ' (autor, bild)' +
      ' values(:autor, :bild) returning id;';
    dm.tFSBild.StartTransaction;
    dm.qFSBild.sql.Text := sql;
    dm.qFSBild.Params.ByNameAsString['autor'] := UTF8Decode(Autor);
    dm.qFSBild.ParamsSetBlob('bild', Fdatei);
    dm.qFSBild.Execute;
    ID := dm.qFSBild.fields.AsInt64[0];
    dm.tFSBild.Commit;
  Except
    on E: Exception Do
    Begin
      dm.tFSBild.RollBack;
      ShowMessage(E.Message);
    End;
  End;
End;


regards

tom