Download file using REST API

Rj27 · ‎09-23-2020

Hi All,

I need to download files attached to any incident using REST API.

I will be sending incident detail from my postman.

Already Referred to attachment api reference docs but could'nt find a solution.

NOTE: I don't have the option to use ui action

Is this doable?

Thanks in Advance!

Hitoshi Ozawa · ‎09-29-2020

I'm executing python script from the command line.

I may be missing some steps below but the general way to install python is as follows.

1. Install python

https://phoenixnap.com/kb/how-to-install-python-3-windows

2. Create subdirectory

mkdir servicenowapis

3. Move to the subdirectory

cd servicenowapis

4. Create a virtualenv

python-m venv venv

5. Activate venv

venv\Scripts\activate.bat

6. Install request module

pip install requests

7. Copy the script I've provided to the directory

8. Copy and paste content of Constants.py over import statements

9. Edit username, password

9. Edit table_api.py to use Incident number

e.g.

get_file_attachment('INC0000002')

10. Execute command

python test_api.py

import requests

SERVICENOW_URL = 'https://<instance>.service-now.com'
SERVICENOW_USER = '<username>'
SERVICENOW_PWD = '<password>'

DOWNLOAD_DIR = './downloads/'

REQUEST_HEADER = {"json": {"Content-Type": "application/xml", "Accept": "application/json"},
                  "png": {"Content-Type": "application/xml", "Accept": "application/png"},
                  "xml": {"Content-Type": "application/xml", "Accept": "application/xml"},
                  }

ATTACHMENT_API = '/api/now/attachment'
TABLE_API = '/api/now/table'
# TABLE_NAME = 'kb_knowledge'
TABLE_NAME = 'incident'


def get_table_data(table_name, param):
    url = SERVICENOW_URL + TABLE_API + '/' + table_name + '?' + param
    response = requests.get(url, auth=(SERVICENOW_USER, SERVICENOW_PWD), headers=REQUEST_HEADER.get('json'))
    if response.status_code != 200:  # if error, then exit
        print('Status:', response.status_code, 'Headers:', response.headers, 'Error Response:', response.json())
        exit()
    return response.json()


def get_attachment_info(sys_id):
    url = SERVICENOW_URL + ATTACHMENT_API + '/' + sys_id
    response = requests.get(url, auth=(SERVICENOW_USER, SERVICENOW_PWD), headers=REQUEST_HEADER.get('json'))
    if response.status_code != 200:  # if error, then exit
        print(f'Status:  {response.status_code}, Headers:{response.headers}')
        exit()
    return response.json()


def get_attachment(att_sys_id, file_type, download_dir):
    url = SERVICENOW_URL + '/' + ATTACHMENT_API + '/' + att_sys_id + '/file'
    response = requests.get(url, auth=(SERVICENOW_USER, SERVICENOW_PWD), headers=REQUEST_HEADER.get(file_type))
    if response.status_code != 200:  # if error, then exit
        print('Status:', response.status_code, 'Headers:', response.headers, 'Error Response:', response.json())
        exit()
    with open(download_dir, 'wb') as f:
        for chunk in response:
            f.write(chunk)


def get_file_attachment(record_number):
    param = 'sysparm_query=number=' + record_number + '&sysparam_limit=1'

    file_info = get_table_data(TABLE_NAME, param).get('result')
    if len(file_info) < 1:
        print(f'There is no attachment to sys_id:{record_number}')
        return
    attachment_sys_id = file_info[0].get('sys_id')

    param = 'sysparm_query=table_sys_id=' + attachment_sys_id + '&sysparam_limit=1'
    kb_attachments = get_table_data('sys_attachment', param)
    result = kb_attachments.get('result')
    for attach_file in result:
        attach_sys_id = attach_file.get('sys_id')
        content_type = attach_file.get('content_type').split('/')
        file_ext = content_type[1]
        file_name = attach_file.get('file_name')
        get_attachment(attach_sys_id, file_ext, DOWNLOAD_DIR + file_name)


if __name__ == '__main__':
    # get_file_attachment('KB0010062')  # knowledge base number
    get_file_attachment('INC0000002')

View solution in original post

RAHUL Khanna1 · ‎10-06-2020

Hi Rj, For my understanding, are you trying to push the attachment s and the incident details to 3rd party, or trying to pull from 3rd party. Can you provide some more info on this.

Rj27 · ‎10-11-2020

Hi Rahul,

I am trying to download the attachment from my instance to local system.
For this, i am using postman to send request.
Basically, i can use use any method EXCEPT ui action. Hence trying with postman and REST.

The above python code helped me after installing python but the problem is not every user will have python installed in their system.