urllib - How to urlencode a querystring in Python?

613
votes

I am trying to urlencode this string before I submit. 

queryString = 'eventName=' + evt.fields["eventName"] + '&' + 'eventDescription=' + evt.fields["eventDescription"];
13
pythonurlliburlencode

13 Answers

636
votes

You need to pass your parameters into urlencode() as either a mapping (dict), or a sequence of 2-tuples, like:

>>> import urllib
>>> f = { 'eventName' : 'myEvent', 'eventDescription' : 'cool event'}
>>> urllib.urlencode(f)
'eventName=myEvent&eventDescription=cool+event'

Python 3 or above

Use:

>>> urllib.parse.urlencode(f)
eventName=myEvent&eventDescription=cool+event

Note that this does not do url encoding in the commonly used sense (look at the output). For that use urllib.parse.quote_plus.

1094
votes

Python 2

What you're looking for is urllib.quote_plus:

safe_string = urllib.quote_plus('string_of_characters_like_these:$#@=?%^Q^$')

#Value: 'string_of_characters_like_these%3A%24%23%40%3D%3F%25%5EQ%5E%24'

Python 3

In Python 3, the urllib package has been broken into smaller components. You'll use urllib.parse.quote_plus (note the parse child module)

import urllib.parse
safe_string = urllib.parse.quote_plus(...)
69
votes

Try requests instead of urllib and you don't need to bother with urlencode!

import requests
requests.get('http://youraddress.com', params=evt.fields)

EDIT:

If you need ordered name-value pairs or multiple values for a name then set params like so:

params=[('name1','value11'), ('name1','value12'), ('name2','value21'), ...]

instead of using a dictionary.

38
votes

Context

  • Python (version 2.7.2 )

Problem

  • You want to generate a urlencoded query string.
  • You have a dictionary or object containing the name-value pairs.
  • You want to be able to control the output ordering of the name-value pairs.

Solution

  • urllib.urlencode
  • urllib.quote_plus

Pitfalls

Example

The following is a complete solution, including how to deal with some pitfalls.

### ********************
## init python (version 2.7.2 )
import urllib

### ********************
## first setup a dictionary of name-value pairs
dict_name_value_pairs = {
  "bravo"   : "True != False",
  "alpha"   : "http://www.example.com",
  "charlie" : "hello world",
  "delta"   : "1234567 !@#$%^&*",
  "echo"    : "[email protected]",
  }

### ********************
## setup an exact ordering for the name-value pairs
ary_ordered_names = []
ary_ordered_names.append('alpha')
ary_ordered_names.append('bravo')
ary_ordered_names.append('charlie')
ary_ordered_names.append('delta')
ary_ordered_names.append('echo')

### ********************
## show the output results
if('NO we DO NOT care about the ordering of name-value pairs'):
  queryString  = urllib.urlencode(dict_name_value_pairs)
  print queryString 
  """
  echo=user%40example.com&bravo=True+%21%3D+False&delta=1234567+%21%40%23%24%25%5E%26%2A&charlie=hello+world&alpha=http%3A%2F%2Fwww.example.com
  """

if('YES we DO care about the ordering of name-value pairs'):
  queryString  = "&".join( [ item+'='+urllib.quote_plus(dict_name_value_pairs[item]) for item in ary_ordered_names ] )
  print queryString
  """
  alpha=http%3A%2F%2Fwww.example.com&bravo=True+%21%3D+False&charlie=hello+world&delta=1234567+%21%40%23%24%25%5E%26%2A&echo=user%40example.com
  """
26
votes

Try this:

urllib.pathname2url(stringToURLEncode)

urlencode won't work because it only works on dictionaries. quote_plus didn't produce the correct output.

21
votes

Note that the urllib.urlencode does not always do the trick. The problem is that some services care about the order of arguments, which gets lost when you create the dictionary. For such cases, urllib.quote_plus is better, as Ricky suggested.

7
votes

In Python 3, this worked with me

import urllib

urllib.parse.quote(query)
5
votes

for future references (ex: for python3)

>>> import urllib.request as req
>>> query = 'eventName=theEvent&eventDescription=testDesc'
>>> req.pathname2url(query)
>>> 'eventName%3DtheEvent%26eventDescription%3DtestDesc'
4
votes

For use in scripts/programs which need to support both python 2 and 3, the six module provides quote and urlencode functions:

>>> from six.moves.urllib.parse import urlencode, quote
>>> data = {'some': 'query', 'for': 'encoding'}
>>> urlencode(data)
'some=query&for=encoding'
>>> url = '/some/url/with spaces and %;!<>&'
>>> quote(url)
'/some/url/with%20spaces%20and%20%25%3B%21%3C%3E%26'
3
votes

If the urllib.parse.urlencode( ) is giving you errors , then Try the urllib3 module .

The syntax is as follows :

import urllib3
urllib3.request.urlencode({"user" : "john" })
1
votes

Another thing that might not have been mentioned already is that urllib.urlencode() will encode empty values in the dictionary as the string None instead of having that parameter as absent. I don't know if this is typically desired or not, but does not fit my use case, hence I have to use quote_plus.

0
votes

For Python 3 urllib3 works properly, you can use as follow as per its official docs :

import urllib3

http = urllib3.PoolManager()
response = http.request(
     'GET',
     'https://api.prylabs.net/eth/v1alpha1/beacon/attestations',
     fields={  # here fields are the query params
          'epoch': 1234,
          'pageSize': pageSize 
      } 
 )
response = attestations.data.decode('UTF-8')