Blob might have been initiated??

[Ian Branch 121]

Hi Team,

I have similar code to below in several places

    //
    pBlob := dmC.jtImages.CreateBlobStream(dmC.jtImages.FieldByName('JTImage'), bmWrite);
    //
    try
      pBlob.Seek(0, soFromBeginning);
      //
      fsFile := TFileStream.Create(sFileName, fmOpenRead or fmShareDenyWrite);
      try
        pBlob.CopyFrom(fsFile, fsFile.Size);
      finally
        fsFile.Free
      end;
    finally
      pBlob.Free
    end;
    //
  end
  else
  begin
    MessageBeep(MB_ICONERROR);
    TaskMessageDlg('File not found!', 'File ' + sFileName + ' not found!', mtError, [mbOK], 0);
    pBlob.Free;
  end;

pBlob is declared as a TStream.

I consistently get the following error message..

"[dcc32 Warning] XXXXXFrm.pas(1213): W1036 Variable 'pBlob' might not have been initialized"

pointing to the last pBlob.Free;

 

I know it is only a Warning but it is annoying in an otherwise clean compile/build.

What am I missing?  How do I rectify this please?

 

Regards & TIA,

Ian

[Guest]

dont economize words:

• what IDE used? --- Is top-secret?
• what component /class is  "jtImages"? (is a TImage from another suite?)
• "dmC" is "DataModule do tipo C"  😄
• etc...

NOTE: depending of your IDE, "BLOB" fields (and others class, like TImage) have procedure to "LoadFromFile" and "SaveToFile", it's not necessary all this code!

 

maybe we forget read your Help System: 

http://docs.embarcadero.com/products/rad_studio/delphiAndcpp2009/HelpUpdate2/EN/html/delphivclwin32/DB_TDataSet_CreateBlobStream.html

http://docs.embarcadero.com/products/rad_studio/delphiAndcpp2009/HelpUpdate2/EN/html/delphivclwin32/DB_TBlobType.htm

{
The following example copies the data in the Notes field of
Table1 or SQLDataSet1 to the Remarks field of ClientDataSet1.
}
procedure TForm1.Button1Click(Sender: TObject);
var
  Stream1: TBlobStream;
  Stream2: TStream;
  blobType : TBlobType;
begin
  blobType := Table1Notes.BlobType;
  Stream1 := TBlobStream.Create(Table1Notes, bmRead);
  try
    CDS2.Edit;
    { here’s a different way to create a blob stream }
    Stream2 := CDS2.CreateBlobStream(CDS2.FieldByName('Remarks'), bmReadWrite);
    try
      Stream2.CopyFrom(Stream1, Stream1.Size);
//    CDS2.Post;
//    CDS2.Active := True;
    finally
      Stream2.Free;
    end;
  finally
    Stream1.Free;
  end;
end;

 

Edited December 14, 2020 by Guest

[Ian Branch 121]

Hi emailx45,

My apologies.  I thought the code was fairly generic and therefore wouldn't need further clarification.  My Bad. 😞

D10.4.1, ElevateDB.

In this case jtImages is an ElevateDB Table Blob field.

Yes, dmC is a datamodule.

 

I am guilty of simple cut & paste when I incorporated my code.

 

I note your alternative code.  TBlobStream appears to be an element of the BDE, which I don't have installed.

 

Ian

[Ian Branch 121]

Actually I just discovered why I was getting the messages.

I was doing a Free of pBlob at the end of the "if FielExists(sFileName) then ..."  and of course nothing had happened with pBlob at that time.

My Bad.

 

Thanks for looking.

 

Ian

[Guest]

ok! the BDE code is sample by Embarcadero, but the new fields blob FireDAC etc... can use loadfile/savefile more easy!

remember: DONT FREE.FREE    

Edited December 14, 2020 by Guest

[Ian Branch 121]

OK.  My thanks to emailx45 for getting me on the right track & overcoming my laziness. 😉

My above code has been condensed to...

    //
    (dmC.jtImages.FieldByName('JTImage') as TBlobField).LoadFromFile(sFileName);
    //

Thank you.

 

Regards,

Ian

[Guest]

1 hour ago, Ian Branch said:

My above code has been condensed to...

• good, but this way is more readable too:  TBlobField(dmC.jtImages.FieldByName('JTImage')).LoadFromFile(sFileName); -- if YOU know it, then, is not necessary use "AS" operator!

DONT FORGET: when working with obj is necessary "know" if it is "nil" or not... avoiding "AV" on the mid-way

Edited December 14, 2020 by Guest

[Ian Branch 121]

Hi amailx45,

Interesting.  That would not have occurred to me in a million years.

Slight problem..  Delphi doesn't like it. :-(  SFileName is an undeclared identifier...

 

Ian

 

[Ian Branch 121]

Interesting.  I retyped the line and it, Delphi, is happy now.

[Guest]

when loading a file is interessant verify is "it" exist yet!

then:

try
   if fncFileExistYet( 'file do verify' ) then
   begin
    table.EDIT;
    TBloabField( xxxx ) loadfile ( xxxxx );  // if occurr any "AV"
     ... another fields actions
    table.POST;
   end;
except
   on E:Exception do
    begin
      table.CANCEL; // any way if in "edit" or not!
      ShowMessage('my error ' + E.Message ); // show the message for last
    end;
end;

 

hug (I'll sleep .. 02:03hrs)

Edited December 14, 2020 by Guest

[Ian Branch 121]

Hi emailx45.  Yes, I have those safeguards, including checking and limiting the image file type/size.  Only .jpg or .jpeg & <256kB.