How to solve this file handling issue?

[GiggsB]

Hi,

I am using the below code to store data on Raspberry Pi using UART whenever it receives any data. Raspberry Pi receives data continuously for 6 seconds. I want to store this data in a single file and open a new one when Raspberry Pi receives data at a later time.

But in my code, whenever Raspberry Pi receives data, a new file is getting created every second and data is being stored in each of those files instead of storing the whole data in the same file. Can someone help/suggest how I can solve the issue? Thanks.

import time
import serial
import datetime
import os

ser = serial.Serial(port='/dev/serial0', baudrate=900000, parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        bytesize=serial.EIGHTBITS, rtscts=1,)

while (True):
    if (ser.inWaiting() > 0):
        outputFilePath = os.path.join(os.path.dirname(__file__),
               datetime.datetime.now().strftime("%dT%H.%M.%S") + ".csv")
        text_file = open(outputFilePath, 'a')
        data_str = ser.read(ser.inWaiting())
        text_file.write(data_str)
        #text_file.flush()
	if ("D" in data_str):        
		text_file.close()
    time.sleep(0.01)

[Gribouillis]

You could perhaps refactor it like this

import time
import serial
import datetime
import os
 
ser = serial.Serial(port='/dev/serial0', baudrate=900000, parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        bytesize=serial.EIGHTBITS, rtscts=1,)
 
def output_file_path():
    return os.path.join(os.path.dirname(__file__),
               datetime.datetime.now().strftime("%dT%H.%M.%S") + ".csv")
 
while (True):
    if ser.inWaiting():
        with open(output_file_path(), 'w') as text_file:
            while True:
                while not ser.inWaiting():
                    time.sleep(0.01)
                data_str = ser.read(ser.inWaiting())
                text_file.write(data_str)
                if "D" in data_str:
                    break
    time.sleep(0.01)

[GiggsB]

You could perhaps refactor it like this

Thank you. It works like a charm. I am a beginner at python, I understood your logic, but I have one doubt. How is this function closing the file, since we are not explicitly closing it? Thanks.

[Gribouillis]

When the program exits the with open... block, the file is automatically closed.