Delphi TZipMaster - how to use the Find method?

Using Delphi XE, TZipMaster 1.91 (latest)

I want to get the file name of first file name matching the FSpec arg that is passed to the Find function. However, I get an access violation when calling this function.

  var
    DBBakFl : String;
    d : Integer;
  begin
    ZipMaster19开发者_StackOverflow1.ZipFileName := 'myzip.zip';

    try
      DBBakFl := ZipMaster191.Find('*.FBK', d).FileName;
    except
      raise Exception.Create('Find raised an exception');
    end;

Any help appreciated.

EDIT: I sent an email got an almost immediate answer from one of the component's authors, Russell Peters. See my answer below.

Try something like:

 var
   DBBakFl : String;
   d : Integer;
   DirEntry: TZMDirEntry;
 begin
   ZipMaster191.ZipFileName := 'myzip.zip';

   DirEntry := ZipMaster191.Find('*.FBK', d);
   if Assigned(DirEntry) then
   begin
     DBBakF1 := DirEntry.FileName;
     ....
   end;

As find is failing, what you are effectively trying is to get the file name from a nil TZMDirEntry. Basically the same as:

var
  DBBakFl : String;
  DirEntry: TZMDirEntry;
begin

  DirEntry := nil;
  DBBakF1 := DirEntry.FileName;
end;

If the call to Find fails, you don't get back a valid TZMDirEntry instance, so you can't access the FileName property.

Try assigning the result of Find to a variable and check it for validity before trying to access its properties or methods. Maybe something like this. The documentation shows that TZMDirEntry is an abstract class, so you might need to use a descendent class instead.

  var
    DBBakFl : String;
    d : Integer;
    lDirEntry: TZMDirEntry;
  begin
    ZipMaster191.ZipFileName := 'myzip.zip';

    lDirEntry := ZipMaster191.Find('*.FBK', d);
    if Assigned(lDirEntry) then
      DBBakFl := lDirEntry.FileName
    else
      ShowMessage('file not found');

I sent an email got an almost immediate answer from one of the component's authors, Russell Peters:

I am not surprise you get an AV

var
  Idx: Integer;
  Entry: TZMDirEntry;
   DBBakFl : String;
 begin
 try
   Idx := -1;  // search from beginning, starts at Idx + 1
   Index := ZipMaster191.Find('*.FBK', Idx);
   if Index <> nil then
      DBBakFl := Index .FileName;
 except
   raise Exception.Create('Find raised an exception');
 end;

OR
var
  Idx: Integer;
   DBBakFl : String;
 begin
 try
   Idx := -1;  // search from beginning, starts at Idx + 1
   if ZipMaster191.Find('*.FBK', Idx) <> nil then
      DBBakFl := ZipMaster191[Idx].FileName;
 except
   raise Exception.Create('Find raised an exception');
 end;

OR

var
  Idx: Integer;
   DBBakFl : String;
 begin
 try
   Idx := -1;  // search from beginning, starts at Idx + 1
   ZipMaster191.Find('*.FBK', Idx) ;
   if Idx >= 0 then
      DBBakFl := ZipMaster191[Idx].FileName;
 except
   raise Exception.Create('Find raised an exception');
 end;

In a loop it is easy

Idx := -1;
while ZipMaster191.Find('*.FBK', Idx) <> nil do
begin
      DBBakFl := ZipMaster191[Idx].FileName;

Russell Peters