CODEWITHSUNDEEP
python
Arun
Arun

Reputation: 1220

Issue in Writing the contents of a variable to a file

I'm trying to get the SPF records of a domains and the domains are read from a file.When i am trying to get the spf contents and write it to a file and the code gives me the results of last domain got from input file. 

Example `Input_Domains.txt`

blah.com
box.com
marketo.com

The output,I get is only for the marketo.com

#!/usr/bin/python

import sys
import socket
import dns.resolver
import re


def getspf (domain):
   answers = dns.resolver.query(domain, 'TXT')
   for rdata in answers:
     for txt_string in rdata.strings:
       if txt_string.startswith('v=spf1'):
         return txt_string.replace('v=spf1','')

with open('Input_Domains.txt','r') as f:
     for line in f:
        full_spf=getspf(line.strip())
my_file=open("out_spf.txt","w")
my_file.write(full_spf)
my_file.close()

How can i solve this by writing all the spf contents of domains which i got it to file,Any suggestions please ?

Upvotes: 0

Views: 45

Answers (2)

machine yearning
machine yearning

Reputation: 10119

Try using a generator expression inside your with block, instead of a regular for loop:

full_spf = '\n'.join(getspf(line.strip()) for line in f)

This will grab all the lines at once, do your custom getspf operations to them, and then join them with newlines between.

The advantage to doing it this way is that conceptually you're doing a single transformation over the data. There's nothing inherently "loopy" about taking a block of data and processing it line-by-line, since it could be done in any order, all lines are independent. By doing it with a generator expression you are expressing your algorithm as a single transformation-and-assignment operation.

Edit: Small oversight, since join needs a list of strings, you'll have to return at least an empty string in every case from your getspf function, rather than defaulting to None when you don't return anything.

Upvotes: 2

The6thSense
The6thSense

Reputation: 8335

It is because you are rewriting full_spf all the time so only last value is stored

with open('Input_Domains.txt','r') as f:
    for line in f:
        full_spf=getspf(line.strip())

Modification:

with open('Input_Domains.txt','r') as f:
    full_spf=""
    for line in f:
        full_spf+=getspf(line.strip())+"\n"

Upvotes: 3

Related Questions