Tag: python

GET and POST requests using Python

- by Pupli 
pip install requests

Making a Get request

# importing the requests library
import requests

# api-endpoint
URL = "http://maps.googleapis.com/maps/api/geocode/json"

# location given here
location = "delhi technological university"

# defining a params dict for the parameters to be sent to the API
PARAMS = {'address':location}

# sending get request and saving the response as response object
r = requests.get(url = URL, params = PARAMS)

# extracting data in json format
data = r.json()


# extracting latitude, longitude and formatted address
# of the first matching location
latitude = data['results'][0]['geometry']['location']['lat']
longitude = data['results'][0]['geometry']['location']['lng']
formatted_address = data['results'][0]['formatted_address']

# printing the output
print("Latitude:%s\nLongitude:%s\nFormatted Address:%s"
    %(latitude, longitude,formatted_address))

Making a POST request

# importing the requests library
import requests

# defining the api-endpoint
API_ENDPOINT = "http://pastebin.com/api/api_post.php"

# your API key here
API_KEY = "XXXXXXXXXXXXXXXXX"

# your source code here
source_code = '''
print("Hello, world!")
a = 1
b = 2
print(a + b)
'''

# data to be sent to api
data = {'api_dev_key':API_KEY,
        'api_option':'paste',
        'api_paste_code':source_code,
        'api_paste_format':'python'}

# sending post request and saving response as response object
r = requests.post(url = API_ENDPOINT, data = data)

# extracting response text
pastebin_url = r.text
print("The pastebin URL is:%s"%pastebin_url)

References
https://www.geeksforgeeks.org/get-post-requests-using-python/
https://www.w3schools.com/python/ref_requests_post.asp

Printing all DNS records using DNSPython in Python

- by Pupli 
import dns.resolver


def get_records(domain):
    """
    Get all the records associated to domain parameter.
    :param domain: 
    :return: 
    """
    ids = [
        'NONE',
        'A',
        'NS',
        'MD',
        'MF',
        'CNAME',
        'SOA',
        'MB',
        'MG',
        'MR',
        'NULL',
        'WKS',
        'PTR',
        'HINFO',
        'MINFO',
        'MX',
        'TXT',
        'RP',
        'AFSDB',
        'X25',
        'ISDN',
        'RT',
        'NSAP',
        'NSAP-PTR',
        'SIG',
        'KEY',
        'PX',
        'GPOS',
        'AAAA',
        'LOC',
        'NXT',
        'SRV',
        'NAPTR',
        'KX',
        'CERT',
        'A6',
        'DNAME',
        'OPT',
        'APL',
        'DS',
        'SSHFP',
        'IPSECKEY',
        'RRSIG',
        'NSEC',
        'DNSKEY',
        'DHCID',
        'NSEC3',
        'NSEC3PARAM',
        'TLSA',
        'HIP',
        'CDS',
        'CDNSKEY',
        'CSYNC',
        'SPF',
        'UNSPEC',
        'EUI48',
        'EUI64',
        'TKEY',
        'TSIG',
        'IXFR',
        'AXFR',
        'MAILB',
        'MAILA',
        'ANY',
        'URI',
        'CAA',
        'TA',
        'DLV',
    ]
    
    for a in ids:
        try:
            answers = dns.resolver.query(domain, a)
            for rdata in answers:
                print(a, ':', rdata.to_text())
    
        except Exception as e:
            print(e)  # or pass

if __name__ == '__main__':
    get_records('google.com')

References
https://gist.github.com/akshaybabloo/2a1df455e7643926739e934e910cbf2e

Capture and Save IP Camera in Python OpenCV

- by Pupli 
import cv2

#print("Before URL")
cap = cv2.VideoCapture('rtsp://[email protected]:554/cam/realmonitor?channel=1&subtype=1')
#print("After URL")

(grabbed, frame) = cap.read()
fshape = frame.shape
fheight = fshape[0]
fwidth = fshape[1]
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (fwidth,fheight))

while True:

    #print('About to start the Read command')
    ret, frame = cap.read()
    #print('About to show frame of Video.')
    cv2.imshow("Capturing",frame)
    #print('Running..')

    out.write(frame)

    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()

References
https://pupli.net/2021/01/access-ip-camera-in-python-opencv/
https://stackoverflow.com/questions/29317262/opencv-video-saving-in-python

Access IP Camera in Python OpenCV

- by Pupli 
import cv2

#print("Before URL")
cap = cv2.VideoCapture('rtsp://admin:[email protected]/H264?ch=1&subtype=0')
#print("After URL")

while True:

    #print('About to start the Read command')
    ret, frame = cap.read()
    #print('About to show frame of Video.')
    cv2.imshow("Capturing",frame)
    #print('Running..')

    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()

References
https://stackoverflow.com/questions/49978705/access-ip-camera-in-python-opencv
https://dahuawiki.com/Remote_Access/RTSP_via_VLC

SQLite3 and multiple processes

- by Pupli

First, avoid concurrent access to sqlite database files. Concurrency is one of sqlite’s weak points and if you have a highly concurrent application, consider using another database engine.

If you cannot avoid concurrency or drop sqlite, wrap your write transactions in BEGIN IMMEDIATE; … END;. The default transaction mode in sqlite is DEFERRED which means that a lock is acquired only on first actual write attempt. With IMMEDIATE transactions, the lock is acquired immediately, or you get SQLITE_BUSY immediately. When someone holds a lock to the database, other locking attempts will result in SQLITE_BUSY.

Dealing with SQLITE_BUSY is something you have to decide for yourself. For many applications, waiting for a second or two and then retrying works quite all right, giving up after n failed attempts. There are sqlite3 API helpers that make this easy, e.g. sqlite3_busy_handler() and sqlite3_busy_timeout() but it can be done manually as well.

You could also use OS level synchronization to acquire a mutex lock to the database, or use OS level inter-thread/inter-process messaging to signal when one thread is done accessing the database.

If you want to use Python’s automatic transaction handling, leave isolation_level at its default value, or set it to one of the three levels.

If you want to do your own transaction handling, you have to prevent Python from doing its own by setting isolation_level to None.

References
https://stackoverflow.com/questions/1063438/sqlite3-and-multiple-processes
https://stackoverflow.com/questions/41915603/python3-sqlite3-begin-immediate-error