How can i read large EmailMessage object using wb if the file is large using python3?-CodePudding

I wish to write a very large EmailMessage object using binary in small sizes just like it is done using buffer.read(1024). IS there a way? I have tried like this which is wrong as the Email Message object is not having read() method:

    with open(complete_path,'wb ') as fp:
        while True:
            x = msg.read(1024)
            if x:
                fp.write(x.as_bytes())
            else:
                break
        fp.write(x.as_bytes())

Here msg is the EmailMessage object and trying to save it at location complete_path When tried with below code it works for most of the mails but does not complete and gets stuck for few mails and generated zombies:

      with open(complete_path,'wb ') as fp:
          fp.write(msg.as_bytes())

I am reading the email in a fuglu plugin and not from a file. Please guide.

CodePudding user response：

Try using this:

import email
import os

# Open the file in binary mode
with open(complete_path, 'rb') as fp:
    msg = email.message_from_binary_file(fp)

# Write the message to a file in binary mode
with open(complete_path, 'wb ') as fp:
    fp.write(msg.as_bytes())

import email
import os

def read_email_from_file(filename):
    with open(filename, 'rb') as fp:
        msg = email.message_from_binary_file(fp)
    return msg

def write_email_to_file(msg, filename):
    with open(filename, 'wb ') as fp:
        fp.write(msg.as_bytes())


def main():
    msg = read_email_from_file(complete_path)
    write_email_to_file(msg, 'email.txt')


if __name__ == '__main__':
    main()

I hope it would help. Change it according to your requirements if you like.

CodePudding user response：

It sounds like you're trying to write an EmailMessage object to a file in binary format, and you want to do it in smaller chunks to avoid running out of memory.

One way to write the EmailMessage object to the file in smaller chunks is to use the as_bytes() method of the EmailMessage object to convert the message to a bytes object, and then write the bytes to the file using the write() method of the file object in a loop. This can be done as follows:

# Convert the EmailMessage object to a bytes object
msg_bytes = msg.as_bytes()

# Open the file in binary write mode
with open(complete_path, 'wb') as fp:
    # Write the bytes to the file in small chunks
    for i in range(0, len(msg_bytes), 1024):
        fp.write(msg_bytes[i:i 1024])

This will write the EmailMessage object to the file in binary format in small chunks, which should avoid running out of memory.

You can then use the read() method of the file object to read the data from the file in smaller chunks, if necessary. For example:

with open(complete_path, 'rb') as fp:
    while True:
        chunk = fp.read(1024)
        if chunk:
            # Do something with the chunk of data
        else:
            break

I hope this helps! Let me know if you have any other questions.

CodePudding user response：

You can use the with statement in Python to read large files. This ensures that the file is properly closed after you are done reading from it, even if an error occurs. Here is an example:

with open('large_file.txt', 'wb ') as f:
  email_message = f.read()

The wb mode opens the file in binary mode for reading and writing. This allows you to read the EmailMessage object from the file and make any necessary changes to it.

Note that if the file is extremely large, it may not fit entirely in memory. In this case, you will need to read the file in chunks and process each chunk separately. You can use the read method to read a specific number of bytes from the file, like this:

chunk_size = 1024  # number of bytes to read at a time
with open('large_file.txt', 'wb ') as f:
  while True:
    chunk = f.read(chunk_size)
    if not chunk:
      # reached the end of the file
      break

    # process the chunk here

This will read the file in chunks of chunk_size bytes, allowing you to process the file in smaller pieces and avoid running out of memory. You can adjust the chunk size to find a balance between memory usage and performance.

CodePudding user response：

You can use the as_bytes() method to convert the EmailMessage object to a bytes object and write it to a file.

Here is an example of how you could do that:

import email

# Create an EmailMessage object
msg = email.message.EmailMessage()
msg['Subject'] = 'Some subject'
msg['From'] = '[email protected]'
msg['To'] = '[email protected]'

# Set the body of the email
msg.set_content('This is the body of the email')

# Convert the EmailMessage object to bytes
msg_bytes = msg.as_bytes()

# Write the bytes to a file
with open(complete_path, 'wb ') as fp:
    fp.write(msg_bytes)

Note that this will write the entire email message to the file in one go, without using a loop like in your code. This should work for most emails, and should not result in zombies or other issues.

If you want to read the email message from the file again, you can use the from_bytes() method to convert the bytes back to an EmailMessage object:

# Read the bytes from the file
with open(complete_path, 'rb') as fp:
    msg_bytes = fp.read()

# Convert the bytes to an EmailMessage object
msg = email.message_from_bytes(msg_bytes)

# Print the subject of the email
print(msg['Subject'])