No GStreamer support on OpenCV

I have a Raspberry Pi CSI camera connected to my Nano. When I run the gst-launch command, found in, in the terminal it works fine, no problem.
But when I’m trying to run the GStreamer with OpenCV in Python the camera is not open.

import cv2
def gstreamer_pipeline (capture_width=1280, capture_height=720, display_width=1280, display_height=720, framerate=60, flip_method=0) :   
    return ('nvarguscamerasrc ! ' 
    'video/x-raw(memory:NVMM), '
    'width=(int)%d, height=(int)%d, '
    'format=(string)NV12, framerate=(fraction)%d/1 ! '
    'nvvidconv flip-method=%d ! '
    'video/x-raw, width=(int)%d, height=(int)%d, format=(string)BGRx ! '
    'videoconvert ! '
    'video/x-raw, format=(string)BGR ! appsink'  % (capture_width,capture_height,framerate,flip_method,display_width,display_height))
cap = cv2.VideoCapture(gstreamer_pipeline(flip_method=0), cv2.CAP_GSTREAMER)
>>> False

I found out that the pre-installed opencv-3.2.0 was built without gstreamer support:

Python 3.6.7 (default, Oct 22 2018, 11:32:17)
[GCC 8.2.0] on linux
Type “help”, “copyright”, “credits” or “license” for more information.
>>> import cv2
>>> print(cv2.getBuildInformation())
GStreamer: NO

How do I proceed?
I used a newly flashed SD card with latest Jetpack.

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