1

can't read all data from file useing Python

inside test.txt there is :

{'God': {u'user1@localhost': {}, u'user2@localhost': {}, u'user3@localhost': {}}}

and the code is :

# coding: utf-8

def read_file(filename):
    data=None
    try:
        fp = file(filename)
        data = fp.read()
        fp.close()
    except: pass
    return data

def read():
    file = 'test.txt'
    db = eval(read_file(file))
    if "God" in db:
        for x in db["God"]:
            data = x
            #print(x) $$ it'll print all data True but I do not need it, I will put instructions inside and I do not need to be repeated.
        print(x) # $$ print just 1 data from file

try: read()
except: pass

how can I let it to read all data from file

thx.

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1
  • 2
    As general advice, never eval what you read in from file. Big security risk. Store/convert your data to a more appropriate form if necessary, but never eval. Commented Feb 4, 2015 at 5:45

4 Answers 4

Reset to default
2

To read all data from a text file just use read method of a file object, e.g.

with open('test.txt','r') as f:
    file_content = f.read()
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Comments

0
  1. Read File using with and open method.
  2. eval file content to get content into dictionary format.
  3. Use has_key to check God key is present or not. [use in 'has_key()' or 'in'?
  4. Use 'keys()method to get all keys of God value` dictionary.
  5. use 'join()` string method

code:

def readFile(filepath):
    with open(filepath, "rb") as fp:
        data = fp.read()         
    db = eval(data)
    if "God" in db:
        godkeys= db["God"].keys()
        print "godkeys:-", godkeys
        print "Data:", ','.join(godkeys)

filepath = '/home/infogrid/Desktop/input1.txt'
readFile(filepath)

output:

$ python  workspace/vtestproject/study/test.py
godkeys:- [u'user3@localhost', u'user2@localhost', u'user1@localhost']
Data: user3@localhost,user2@localhost,user1@localhost
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5 Comments

hi, much time taken for to do ctrl+k
has_key has been deprecated for years - preferred form is if "God" in db:
@PaulMcGuire: ok. but can you give more information on it.
@VivekSable - see details in this question stackoverflow.com/questions/1323410/has-key-or-in
@mr.somebody: Working, then upvote/accept answer :), just kidding :)
0

instead of using file() try open() in fact you should get in the habit of that. Developers are directed to use open() instead of file() in all cases.

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1 Comment

same thing file() or open() print just 1 data
-1 
db = eval(read_file(file))

db is a dictionary. Dictionary is collection of many pairs of key and value. To check if some key is in dict, we should use keys() function as below:

if "God" in db.keys():

Also, to get all data in dict, we just use items() to get pair of key and value.

for key, value in db["God"].items():
    print "Key", key
    print "Value", value
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4 Comments

In line with other commenters' cautions about using eval, safer to use ast.literal_eval, which does not have the same risks of accidental or malicious command injection.
if "God" in db: is sufficient to check for a matching key, without incurring the overhead of building the list of keys by calling keys().
we can use if db.has_key("God") instead
Unless you are targeting Python 2.2 or older, please don't use the deprecated method has_key, see comments on VivekSable's answer.

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