AttributeError: 'Mesh' object has no attribute 'view_frame'

Question

I am trying to get the pixel coordinates of the object in the rendered image in blender using the How to find image coordinates of the rendered vertex? But I get the error AttributeError: 'Mesh' object has no attribute 'view_frame'

# Test the function using the active object (which must be a camera)
# and the 3D cursor as the location to find.
import bpy
import bpy_extras

scene = bpy.context.scene
obj = bpy.context.object
co = bpy.context.scene.cursor_location

co_2d = bpy_extras.object_utils.world_to_camera_view(scene, obj, co)
print("2D Coords:", co_2d)

Answer 1

Camera object

the argument obj must be a camera

>>> bpy_extras.object_utils.world_to_camera_view(
world_to_camera_view(scene, obj, coord)
Returns the camera space coords for a 3d point.
(also known as: normalized device coordinates - NDC).
Where (0, 0) is the bottom left and (1, 1)
is the top right of the camera frame.
values outside 0-1 are also supported.
A negative 'z' value means the point is behind the camera.
Takes shift-x/y, lens angle and sensor size into account
as well as perspective/ortho projections.
:arg scene: Scene to use for frame size.
:type scene: :class:`bpy.types.Scene`
:arg obj: Camera object.
:type obj: :class:`bpy.types.Object`
:arg coord: World space location.
:type coord: :class:`mathutils.Vector`
:return: a vector where X and Y map to the view plane and
   Z is the depth on the view axis.
:rtype: :class:`mathutils.Vector`

Running your question script with a mesh object as context will produce the error shown. Make sure obj.type == 'CAMERA'.