Attempting to preprocess an object with custom attributes results in an exception

[denisvmedyantsev]

The bug can be reproduced with 2 elements: 1st is a pyfunc that adds some attribute to object X, 2nd is an inferring element with meta preprocessing of X object. We also can replace preprocessing with a second pyfunc.

name: test
parameters:
  batch_size: 1
pipeline:
  source:
    element: videotestsrc
    properties:
      num-buffers: 1
  elements:
    - element: pyfunc
      module: samples.test.test
      class_name: Test1
    - element: pyfunc
      module: samples.test.test
      class_name: Test2

test.py

import pyds

from savant.deepstream.meta.frame import NvDsFrameMeta
from savant.deepstream.meta.object import _NvDsObjectMetaImpl, ObjectMeta
from savant.deepstream.pyfunc import NvDsPyFuncPlugin
from savant.deepstream.utils import (
    nvds_frame_meta_iterator,
    nvds_get_all_obj_attrs,
    nvds_obj_meta_iterator,
)
from savant.gstreamer import Gst

class Test1(NvDsPyFuncPlugin):
    def process_frame(self, buffer: Gst.Buffer, frame_meta: NvDsFrameMeta):
        for obj_meta in frame_meta.objects:
            obj_meta.add_attr_meta('global_roi', 'is_inside', True)

class Test2(NvDsPyFuncPlugin):
    def process_buffer(self, buffer: Gst.Buffer):
        nvds_batch_meta = pyds.gst_buffer_get_nvds_batch_meta(hash(buffer))
        for nvds_frame_meta in nvds_frame_meta_iterator(nvds_batch_meta):
            for nvds_obj_meta in nvds_obj_meta_iterator(nvds_frame_meta):
                object_meta = _NvDsObjectMetaImpl.from_nv_ds_object_meta(
                    nvds_obj_meta, nvds_frame_meta
                )
                user_parent_object_meta = None
                user_object_meta = ObjectMeta(
                    object_meta.element_name,
                    object_meta.label,
                    object_meta.bbox.copy(),
                    object_meta.confidence,
                    object_meta.track_id,
                    user_parent_object_meta,
                    attributes=nvds_get_all_obj_attrs(
                        frame_meta=nvds_frame_meta,
                        obj_meta=object_meta.ds_object_meta,
                    ),
                )

Exception

 ERROR insight::savant::pyfunc                      > Failed to process buffer/frame.
Aliases for entries in sys.path:
    <pwd>: /opt/savant
    <pwd>: /opt/savant
Traceback (most recent call last):
    <pwd> /gst_plugins/python/pyfunc.py:185  do_transform_ip  self.pyfunc.instance.process_buffer(buffer)
    <pwd> /samples/test/test.py:36           process_buffer   user_object_meta = ObjectMeta(
    <pwd> /savant/meta/object.py:105         __init__         if (attr.element_name, attr.name) not in self._attributes:
AttributeError: 'list' object has no attribute 'element_name'

[denisvmedyantsev]

Original error from preprocessor