Delphi load image save as blob in a sql database - sql

Question

I'm trying to load a Image control from a image blob saved previously in a sql database.I have testd so many ways and i can't make it work. The image blob is saved as:
qry.SQL.Text := 'update tbl set pic = :blobVal where id = :idVal';
qry.Parameters.ParamByName('blobVal').LoadFromFile('c:\sample.jpg', ftBlob);
qry.Parameters.ParamByName('idVal').Value := 1;
any suggestion?

Answer 1

There a a lot of treads here about loading images to as database, but I did not find one with update or insert parameters.
You might simply assign a graphic object to your parameter.
If you want to store different graphic types you should add a column
keeping the Information which kind of graphic should be stored (e.g. jpeg,bmp,png).
to be able to create the needed TGraphic class descendant if you want to retrieve the picture from the database.
uses jpeg, pngimage;
type
TitTYPES=(itJPG,itPNG,itBMP);
procedure TDEMO.Button1Click(Sender: TObject);
var
jp:TJpegimage;
g:TGraphic;
begin
jp:=TJpegimage.Create;
try
ads.Close;
jp.LoadFromFile('C:\Bilder1\PIC.jpg');
ads.SQL.Text := 'Insert into IMGBlob (ID,Blob,typ) Values (:ID,:BLOB,:typ)';
ads.Parameters[0].Value := 1;
ads.Parameters[1].Assign(jp);
ads.Parameters[2].Value := itJPG;
ads.ExecSQL;
ads.SQL.Text := 'Select * from IMGBlob where ID=:ID';
ads.Parameters[0].Value := 1;
ads.Open;
try
case TitTYPES(ads.FieldByName('typ').AsInteger) of
itJPG: g:=TJpegimage.Create;
itPNG: g:=TPNGImage.Create;
itBMP: g:=TBitmap.Create;
end;
g.Assign(ads.FieldByName('Blob'));
Image1.Picture.Assign(g);
finally
g.Free;
end;
finally
jp.Free;
end;
end;

Answer 2

To load a BLOB field into an image, you need to use TDataSet.CreateBlobStream.
var
Stream: TStream;
JPG: TJpegImage;
begin
JPG := TJpegImage.Create;
try
Stream := Qry.CreateBlobStream(Qry.FieldByName('BLOBVAL'), bmRead);
try
JPG.LoadFromStream(Stream);
finally
Stream.Free; // edited
end;
finally
JPG.Free;
end;
end;
To store the image back, you'll need to do the reverse:
var
Stream: TBlobStream;
Jpg: TJpegImage;
begin
Jpg := TJpegImage.Create;
try
Jpg.Assign(Image1.Picture.Graphic);
// Assign other query parameters here
Stream := Qry.CreateBlobStream(Qry.FieldByName('BLOBVAL'), bmWrite);
try
Jpg.SaveToStream(Stream);
Qry.ExecSQL;
finally
Stream.Free;
end;
finally
Jpg.Free;
end;
end;
TDBImage is only designed to work with bitmaps (when the field is ftGraphic), so it won't work with JPEG images directly. The easiest thing to do is to load the blob as a JPEG, and assign it to a standard TImage.Picture.Graphic in an event handler for the dataset (such as it's AfterScroll event).

Answer 3

save to db:
var
ms:tmemorystream;
Begin
ms:=tmemorystream.create;
ms.position:=0;
image1.picture.bitmap.savetostream(ms);
ms.position:=0;
with yourfield as tblobfield do
loadfromstream(ms);
freeandnil(ms);
end;
Load from db:
var
ms:tmemorystream;
Begin
ms:=tmemorystream.create;
ms.position:=0;
with yourfield as tblobfield do
savetostream(ms);
ms.position:=0;
image1.picture.bitmap.loadfromstream(ms);
freeandnil(ms);
end;

Answer 4

It does not work with all graphic types like PNG etc.
This one does work on PNG as well:
var mBitmap : TGraphic;
var mStream : TStream;
var mClass : TGraphicClass;
begin
mStream := Query.CreateBlobStream(Query.FieldByName('yourBlobfield'), bmRead);
mClass := GetGraphicClassForFileExtension(mStream.ReadAnsiString);
mBitmap := mClass.Create;
mBitmap.LoadFromStream(mStream);
Image4.Picture.Assign(mBitmap);
end;