handling duplicate keys in HTTP post in order to specify multiple values

Question

Background

• python 2.7
• requests module
• http post with duplicate keys to specify multiple values

Problem

Trevor is using python requests with a website that takes duplicate keys to specify multiple values. The problem is, JSON and Python dictionaries do not allow duplicate keys, so only one of the keys makes it through.

Goal

• The goal is to use python requests to create an HTTP post with duplicate keys for duplicate names in the POST name-value pairs.

Failed attempts

## sample code
payload = {'fname': 'homer', 'lname': 'simpson'
         , 'favefood': 'raw donuts'
         , 'favefood': 'free donuts'
         , 'favefood': 'cold donuts'
         , 'favefood': 'hot donuts'
         }
rtt = requests.post("http://httpbin.org/post", data=payload)

See also

Web links:

• https://duckduckgo.com/?q=python+requests

Question

• How can Trevor accomplish this task using python requests?

Answer 1

You can composite payload in this way:

payload = [
    ('fname', 'homer'), ('lname', 'simpson'),
    ('favefood', 'raw donuts'), ('favefood', 'free donuts'),
]
rtt = requests.post("http://httpbin.org/post", data=payload)

But if your case allows, I prefer POST a JSON with all 'favefoood' in a list:

payload = {'fname': 'homer', 'lname': 'simpson', 
    'favefood': ['raw donuts', 'free donuts']
}
# 'json' param is supported from requests v2.4.2
rtt = requests.post("http://httpbin.org/post", json=payload)

Or if JSON is not preferred, combine all 'favefood' into a string (choose separator carefully):

payload = {'fname': 'homer', 'lname': 'simpson',
    'favefood': '|'.join(['raw donuts', 'free donuts']
}
rtt = requests.post("http://httpbin.org/post", data=payload)