AttributeError: Calling operator "bpy.ops.import_scene.obj" error, could not be found

Question

I am trying to write a python script that will convert triangular-mesh objects to quad-mesh objects.

For example, image (a) will be my input (.obj/.stl) file and image (b) will be the output.

I am a noob with mesh-algorithms or how they work all together. So, far this is the script I have written:

import bpy

inp = 'mushroom-shelve-1-merged.obj'


# Load the triangle mesh OBJ file
bpy.ops.import_scene.obj(filepath=inp, 
                        use_smooth_groups=False,
                        use_image_search=False)

# Get the imported mesh
obj = bpy.context.selected_objects[0]

# Convert triangles to quads
# The `beauty` parameter can be set to False if desired
bpy.ops.object.mode_set(mode='EDIT')
bpy.ops.mesh.select_all(action='SELECT')
bpy.ops.mesh.tris_convert_to_quads(beauty=True)
bpy.ops.object.mode_set(mode='OBJECT')

# Export to OBJ with quads
bpy.ops.export_scene.obj(filepath='quad_mesh.obj')

This results in the following error:

Traceback (most recent call last):
  File "/home/arrafi/mesh-convert-application/test.py", line 8, in <module>
    bpy.ops.import_scene.obj(filepath=inp, 
  File "/home/arrafi/mesh-convert-application/venv/lib/python3.10/site-packages/bpy/4.0/scripts/modules/bpy/ops.py", line 109, in __call__
    ret = _op_call(self.idname_py(), kw)
AttributeError: Calling operator "bpy.ops.import_scene.obj" error, could not be found

Any help with what I am doing wrong here would be greatly appreciated.

• Also please provide your suggestions for if you know any better way to convert triangular-mesh to quad-mesh with Python.
• If you guys know of any API that I can call with python to do the conversion, that would work too.

Answer 1

Turns out bpy.ops.import_scene.obj was removed at bpy==4 which is the latest blender-api for python, hence the error. In bpy>4 you have to use bpy.ops.wm.obj_import(filepath='')

I just downgraded to bpy==3.60 to import object directly in the current scene.

pip install bpy==3.6.0

I also modified my script to take input of .obj files in triangular-mesh and then convert the mesh to quadrilateral, then export as both stl and obj. Here's my working script:

def convert_tris_to_quads(obj_path, export_folder):
    try:
        filename = os.path.basename(obj_path).split('.')[0]
        logging.info(f"Importing {obj_path}")

        bpy.ops.object.select_all(action='DESELECT')
        bpy.ops.object.select_by_type(type='MESH')
        bpy.ops.object.delete()
    
        bpy.ops.import_scene.obj(filepath=obj_path)
        print("current objects in the scene: ", [obj for obj in bpy.context.scene.objects])
        for obj in bpy.context.selected_objects:
            bpy.context.view_layer.objects.active = obj
            
        logging.info("Converting mesh")
        bpy.ops.object.mode_set(mode='EDIT')
        bpy.ops.mesh.select_all(action='SELECT')
        bpy.ops.mesh.tris_convert_to_quads()
        bpy.ops.object.mode_set(mode='OBJECT')

        # Export to OBJ
        obj_export_path = export_folder + filename + '_quad.obj'
        logging.info(f"Exporting OBJ to {obj_export_path}")
        bpy.ops.export_scene.obj(filepath=obj_export_path, use_selection=True)

        # Export to STL
        stl_export_path = export_folder + filename + '_quad.stl'
        logging.info(f"Exporting STL to {stl_export_path}")
        bpy.ops.export_mesh.stl(filepath=stl_export_path, use_selection=True)

    except Exception as e:
        logging.error(f"Error processing {obj_path}: {e}")
        return False

This still might not be the best approach to this, so do let me know if anyone know any better approach.