Hassle free web communication with urequests.py

December 25

In Micropython, I use the uRequests module extensively to send GET requests to retrieve or action PHP scripts on my webserver. I use this is mostly to send and receive data from a web based database, but the possibilities go much further than that.
The uRequests module handles all of the coding involved in setting up sockets and protocols, handshaking and communicating with servers.
You just install your PHP script on the server, and access it by starting an internet connection in your python code, and sending one request to the server such as "result = urequests.get(url, webpage.php)".

Here is some sample code for uploading some data from a text log to an online database.
Say we want to log battery voltage, temperature, pressure and humidity from sensors every hour along with a timestamp.
As I am running my units on batteries, I don't want to expend the power to use wifi every hour, so I save these in a text file and upload periodically, say twice a day.
Write your code to take these readings and save to a textfile ready formatted to be sent as a PHP query string. This is basically a string with key/value pairs joined by the ampersand character.
You may end up with something like this

voltage=4.4&temp=18.45&humidity=74.87&pressure=1032×tamp=10-12-2025 09:45:00
voltage=4.4&temp=18.45&humidity=74.87&pressure=1032×tamp=10-12-2025 10:45:00
voltage=4.3&temp=18.45&humidity=74.87&pressure=1032×tamp=10-12-2025 11:45:00
voltage=4.3&temp=18.45&humidity=74.87&pressure=1032×tamp=10-12-2025 12:45:00
voltage=4.2&temp=18.45&humidity=74.87&pressure=1032×tamp=10-12-2025 13:45:00

A simple PHP script to accept this data. This is for demonstration only, and contains no validation or error checking.

require ('../../../connect_db.php'); #the location of your SQL database connection string $result='FAIL'; #send success or failure to calling code $batt= $_GET['voltage']; #retreive the values from the query string value pairs into variables $temp= $_GET['temp']; $hum= $_GET['hum']; $pres= $_GET['pres']; $time= $_GET['time']; #create your SQL statement and run it to enter the data into your database $sql = "INSERT INTO logdata (batt, temp, hum, pres, timestamp) VALUES ($batt, $temp, $hum, $pres, '$time');"; $r = mysqli_query ( $dbc, $sql ); $result='OK'; #if it got this far, all good echo $result;
In uPython the code to upload the data would go something like this.
You need to import the urequests module into your code. "import urequests"

url = "http://mywebsite/datalogger/upload.php?" f = open("datalog.txt","r") dataline = '' while dataline not 'EOF' #use strip to remove any carriage return or line feed characters. dataline = f.readline().strip() #replace any spaces with "%20", the HTML for space. If there is a space in #the query string PHP will not work, and there is a space in the timestamp. dataline = dataline.replace(' ', '%20') response = urequests.get(url, dataline) #the response object contains the answer from the server, ie an #error code, or anything the page would send to a browser. f.close() #check the page returned OK and not FAIL, and remove the file if response.text.find('OK') > -1: os.remove("datalog.txt")

Using requests GET for this type of scenario is very straightforward but does have its drawbacks, a major one being security.
GET is not secure at all, as everything is in plain text. A more secure way of sending data is using requests.POST()
but there are caveats which I will go into in the next article.

Using requests to POST data