How to use tempfile.NamedTemporaryFile() to save an image?

Question

I am trying to a write a code in Python that will get a picture of a dashboard in tableau and send it to a slack channel. first part works perfectly and saves the image to my local laptop. But when trying to save the image in a temp path and send it to a channel I get the error:

---> 45 f = {'file': (temp_file.name, open(temp_file.name, 'rb'), 'png')} 

46 response = requests.post(url='slack./com/api/files.upload', data= 47 {'token': bot_token, 'channels': slack_channels, 'media': f,'initial_comment' :''}, 

PermissionError: [Errno 13] Permission denied: 'C:\\Users\\Userlogin-~1\\AppData\\Local\\Temp\\tmp3fzm10gj.png'

Here is the code:

import requests 
from slack import WebClient
    
from datetime import date, timedelta, datetime
    
import tableauserverclient as TSC
from tableau_api_lib import TableauServerConnection
from tableau_api_lib.utils.querying import get_views_dataframe, get_view_data_dataframe

req_option = TSC.RequestOptions().page_size(1000)
image_req_option = TSC.ImageRequestOptions(imageresolution=TSC.ImageRequestOptions.Resolution.High)

with server.auth.sign_in(tableau_auth):
    all_workbooks, pagination_item = server.workbooks.get(req_option)
    workbook_id_ = [workbook.id for workbook in all_workbooks if workbook.name == workbook_name][0]
    workbook = server.workbooks.get_by_id(workbook_id_)
    all_views= workbook.views

    for view_item in all_views:
        if view_item.name == view_name:
            with tempfile.NamedTemporaryFile(suffix='.png', delete=True) as temp_file:
                server.views.populate_image(view_item, req_options=image_req_option)
                temp_file.write(view_item.image)
                print('image is created')
                # I get the error after the print
                f = {'file': (temp_file.name, open(temp_file.name, 'rb'), 'png')}
                response = requests.post(url='https://slack./com/api/files.upload', data=
                           {'token': bot_token, 'channels': slack_channels, 'media': f, 'initial_comment' :''},
                           headers={'Accept': 'application/json'}, files=f)
                print('the image is in the channel')

Answer 1

The error occurs because you are trying to re-open an already opened file here:

f = {'file': (temp_file.name, open(temp_file.name, 'rb'), 'png')}

Try instead:

temp_file.file.seek(0)  # change the position to the beginning of the file
f = {'file': (temp_file.name, temp_file, 'png')}