[Lazarus] View Graphic File

[Allan E. Registos]

On Thursday, 20 February, 2014 05:07 PM, Antonio Fortuny wrote:
>
> Le 20/02/2014 07:43, Allan E. Registos a écrit :
>> Hi all,
>>
>> A noob question, I have trouble trying to port an existing vb.net
>> snippet to pascal.
>> Can anyone provide a code snippet where we can download and view a
>> file from a Database?  A binary(jpeg/pdf file) was uploaded to a
>> database table. The code will just download the file uploaded and
>> view it.
>>
>> In vb.net this can be done:
>>
>> /      if conn.State = ConnectionState.Closed Then conn.Open()//
>> //            sql = "Select binfile from graphicfiles WHERE id=" & id//
>> //
>> //            cmd = New NpgsqlCommand(sql, conn)//
>> //
>> //            Dim fileData As Byte() =
>> DirectCast(cmd.ExecuteScalar(), Byte())//
>> //
>> //            Dim sTempFileName As String = Path.GetTempPath & "\" &
>> sFileName//
>> //
>> //            If Not fileData Is Nothing Then//
>> //
>> //                'Read image data into a file stream //
>> //                Using fs As New FileStream(sTempFileName,
>> FileMode.OpenOrCreate, FileAccess.Write)//
>> //                    fs.Write(fileData, 0, fileData.Length)//
>> //                    'Set image variable value using memory stream. //
>> //                    fs.Flush()//
>> //                    fs.Close()//
>> //                End Using//
>> //
>> //                Process.Start(sTempFileName) 'Open file//
>> //
>> //            End If//
>> /
> Sounds quite easy to translate:
> 1. install the sqldblaz package if not yet done
> 2. onto a form or a datamodule drop a connection named DB
> (correcpondig to your DB) and a transaction named TR; link them
> 3. drop a TSqlQuery, link it to the connection and the transacton just
> dropped (name Q)
> 4. fill in the Sql property/. /I assume that the column binfile is a
> binay blob
> ...
> var
>     fs: TMemoryStream;
> begin
> ...
> fs := TMemoryStream.Create;
> try
>     DB.DatabaseName := 'whatever connection could be';
>     DB..UserName := 'sysdba';
>     DB.Password := 'your password';
>     DB.Connected := True;
>     Q.Sql.Text := Format('Select binfile from graphicfiles WHERE
> id=%d/'/, [id]);/        // assuming id is an integer, adapt the
> format otherwise/
>     TR.StartTransaction;
>     Q.Prepare;
>     Q.Open;
>     if Q.Eof = False then begin
>         fs.Position := 0;
>         TBlobField(Q.FieldByName('binfile')).SaveToStream(fs);
>         ...
>         fs.Position := 0;         // reset position to beginning of
> stream
>         do  whatever you need to do with the stream "fs"
>         use stream length by fs.Size
>         fs.SaveToFile('any file name');
>         // for an image dropped onto a form:
>         Image.Picture.LoadFromStream(fs);
>         ... etc...
>
>         ...
>     end;
>     Q.Close;
> finally
>     TR.Commit
>     fs.Free
> end
>
> This should work as it is a code snippet used in one of my programs
> (cleaned and simplified). In my case the DBMS is Firebird but this
> should work with any other supported by SqlDbLaz package.
Many Thanks! Antonio. I will use and save your code for future use.

Regards,
Allan
>
> Antonio.
>
> Thanks,,
>> Allan
>>
>>
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>
>
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