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Javier Aguirre · Guest

Greetings
I hope someone can help me with this...
I have diferent kind of documents in a blob field in a Access database.
My problem is when I try to retrieve and show them, because the program don't
know what kind is the file stored in the field, I want to use the TOLEContainer
to show the file contents as the Access forms do, so I use streams to pass the
data from the field to the container but I only get errors of insufficent memory
or incompatible stream format.
I try with the LoadFromStream and LoadFromFile using as example the code of the
original component and get nothing.

Here is an example of my code:

procedure TForm1._OnActivate(Sender: TObject);
begin
Blob:=TBlobField.Create(Data.adoTarticulo);
Blob.FieldName:='Documento';
Blob.Name:=Data.adoTarticulo.name+Blob.FieldName;
Blob.Index:=Data.adoTarticulo.FieldCount;
Blob.DataSet:=Data.adoTarticulo;
Data.Documentos.Open;
Data.adoTarticulo.Open;
end;

procedure TForm1._Registros(Sender: TObject; Button: TNavigateBtn);
var
Buffer : TAdoBlobStream; // I use TMemoryStream, TStream, and other
// compatible objets and nothing happens
Tamano : integer;
begin
if not Blob.IsNull then
with Data.adoTArticulo do
begin
if not(Active) then Open;
Buffer:=TAdoBlobStream.Create(Blob,bmRead);
Blob.SaveToStream(buffer);
try
Ole1.LoadFromStream(Buffer); // Here is where I get the error
Ole1.DoVerb(ovShow);
finally
Buffer.Free;
end;
end;
end;

Please, I appreciate any idea to resolve this...

Thanks

Javier

Mike Shkolnik · Guest

TOLEContainer have the own format streaming (LoadFromStream/SaveToStream).
Just save your BLOB contents to temporary file and use the
TOLEContainer.CreateObjectFromFile method instead

--
With best regards, Mike Shkolnik
EMail: [email]mshkolnik (AT) scalabium (DOT) com[/email]
http://www.scalabium.com

"Javier Aguirre" <jad (AT) ec-red (DOT) com> wrote

Javier Aguirre · Guest

Hello Mike
One of the problems I found with this method is I don't know the kind of object
or the original filename, in this case, how can I determine the correct type of
object?
I guess there is some method or function in the ADO interface that allow me to
retrieve the kind of data store in the BLOB field. This would be usefull to
create the file and then create the object from file...

Greetings
Javier

Mike Shkolnik wrote:

Glenn De Tollenaere · Guest

Javier,

I guess this is not possible.
Wouldn't it be easier to save the extension somewhere in your databasetable,
next to the contents (BLOB) ?

For instance, add 'FILETYPE' to your databasedefinition and fill it with the
file-extension. That way you will be able to save the contents of the BLOB
to a temporary-file with the correct extension.

Regards
Glenn

"Javier Aguirre" <jad (AT) ec-red (DOT) com> wrote

Vitali Kalinin · Guest

You are wrongly manipulating with Blob stream, try to change it this way
(assuming that Blob content is valid and acceptable for TOleContainer):
procedure TForm1._Registros(Sender: TObject; Button: TNavigateBtn);
var
Buffer : TAdoBlobStream; // I use TMemoryStream, TStream, and other
// compatible objets and nothing happens
Tamano : integer;
begin
if not Blob.IsNull then
with Data.adoTArticulo do
begin
if not(Active) then Open;
Buffer := CreateBlobStream(Blob, bmRead);
try
Ole1.LoadFromStream(Buffer);
Ole1.DoVerb(ovShow);
finally
Buffer.Free;
end;
end;
end;

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