sending data using post in python to php with variable

I don't mean to sound harsh, but being new to a language is no excuse for not learning the language's syntax (quite on the contrary). This line:

data = "POSTDATA=FromDate="i&ToDate="i"&Countrycode=&InsertedSinceDate=&UpdatedSinceDate=&Pollutant=PM10&Namespace=&Format=XML&UserToken="

is obviously broken and raises a SyntaxError:

bruno@bigb:~/Work/playground$ python
Python 2.7.3 (default, Jun 22 2015, 19:33:41) 
>>> data = "POSTDATA=FromDate="i&ToDate="i"&Countrycode=&InsertedSinceDate=&UpdatedSinceDate=&Pollutant=PM10&Namespace=&Format=XML&UserToken="
  File "<stdin>", line 1
    data = "POSTDATA=FromDate="i&ToDate="i"&Countrycode=&InsertedSinceDate=&UpdatedSinceDate=&Pollutant=PM10&Namespace=&Format=XML&UserToken="
                               ^
SyntaxError: invalid syntax
>>> 

In this statement the rhs expression actually begins with :

• "POSTDATA=FromDate=" which is a legal literal string
• i&ToDate which is parsed as "i" (identifier) "&" (operator) "ToDate" (identifier)

The mere juxtaposition of a literal string and an identifier (without an operator) is actually illegal:

bruno@bigb:~/Work/playground$ python
Python 2.7.3 (default, Jun 22 2015, 19:33:41) 
>>> i = 42
>>> "foo" i
  File "<stdin>", line 1
    "foo" i
          ^
SyntaxError: invalid syntax
>>> 

Obviously what you want here is string concatenation, which is expressed by the add ("+") operator, so it should read:

"POSTDATA=FromDate=" + i

Then since "&ToDate" is supposed to be a string literal instead of an operator and a variable you'd have to quote it:

"POSTDATA=FromDate=" + i + "&ToDate="

Then concatenate the current date again:

"POSTDATA=FromDate=" + i + "&ToDate=" + i + "etc..."

Now in your code i (not how I would have named a date BTW but anyway) is a datetime object, not a string, so now you'll get a TypeError because you cannot concatenate a string with anything else than a string (hopefully - it wouldn't make any sense).

FWIW what you want here is not a datetime object but the textual ("string") representation of the date in the "YYYY-MM-DD" format. You can get this from the datetime object using it's strftime() method:

today = datetime.datetime.now().strftime("%Y-%m-%d)

Now you have a string that you can concatenate:

data = "POSTDATA=FromDate=" + today + "&ToDate=" + today + "etc..."

This being said:

• this kind of operation is usually done using string formatting
• and as Ekrem Dogan mentionned, the simplest solution here is to use a higher-level package that will take care of all the boring details of HTTP requests - requests being the de facto standard.

Forget urllib and urllib2 libraries. I recommend you to use requests library.

Here, solution of your problem using requests library:

import requests, datetime

url = 'http://fme.discomap.eea.europa.eu/fmedatastreaming/AirQuality/AirQualityUTDExport.fmw'
i = datetime.datetime.now()

# add as many parameters as you like
payload = {'FromDate': i, 'ToDate': i, 'Pollutant': 'PM10', 'Format': 'XML'}

# here's the magic happens
r = requests.get(url, params=payload)

# status code of response
print r.status_code

# response text
print r.text 

I want to replace the date 2015-05-01 (from and to) with the current date

To replace the date, you could use string formatting. To post the request and to print the response into stdout:

#!/usr/bin/env python2
import urllib2
import sys
from datetime import date
from contextlib import closing
from shutil import copyfileobj
from urllib import quote

url = 'http://fme.discomap.eea.europa.eu/fmedatastreaming/AirQuality/AirQualityUTDExport.fmw'
data = "POSTDATA=FromDate={now}&ToDate={now}".format(now=quote(date.today()))
data += "&Countrycode=&InsertedSinceDate=&UpdatedSinceDate=&Pollutant=PM10&Namespace=&Format=XML&UserToken=" 
with closing(urllib2.urlopen(url, data)) as response:
    copyfileobj(response, sys.stdout)

In general, consider urllib.urlencode(), to create application/x-www-form-urlencoded data instead of doing it manually.