vtkXdmf3Reader::GetNumberOfGrids() doesn't work for single grid
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
When reading a file which contains a single atomic ("uniform" in xdmf terms of "vtkDataSet" in vtk terms) grid,
vtkXdmf3Reader *xreader = vtkXdmf3Reader::New();
xreader->SetFileName("data/brick-w-hole.xmf");
xreader->Update();
std::cout << xreader->GetNumberOfGrids() << std::endl;
reports 0 instead of 1. Ignoring this and just reading
vtkDataObject *rOutput = xreader->GetOutputDataObject(0);
assert(rOutput != nullptr);
vtkUnstructuredGrid * m = dynamic_cast<vtkUnstructuredGrid*>(rOutput);
assert(m != nullptr);
works.