tornado maps GET and POST arguments to lists. How can I disable this "feature"?

python json tornado cyclone
Abe picture Abe · Apr 27, 2012 · Viewed 26.2k times · Source

The HTTPRequest class in the tornado* web framework helpfully maps GET and POST arguments to lists. I understand why -- in case a given argument name is used multiple times. But for some RequestHandlers, this is a pain. For instance, if I want to pass a json object and parse it as-is on the server.

What's the most straightforward way to disable the map-to-list behavior so that I can send unaltered json to a tornado/cyclone server?

*Cyclone, actually, in case there's an implementation difference here.

Answer

koblas picture koblas · Apr 27, 2012

Instead of accessing self.request.arguments directly you should use the accessor functions:

self.get_argument("ID", default=None, strip=False)

This returns a single item.

If you want to turn the arguments into a JSON object you can quite easily do so: 

json.dumps({ k: self.get_argument(k) for k in self.request.arguments })

Related questions

Python JSON encoder to support datetime?

is there any elegant way to make Python JSON encoder support datetime? some 3rd party module or easy hack? I am using tornado's database wrapper to fetch some rows from db to generate a json. The query result includes a …

Read More
Why can't Python parse this JSON data?

I have this JSON in a file: { "maps": [ { "id": "blabla", "iscategorical": "0" }, { "id": "blabla", "iscategorical": "0" } ], "masks": [ "id": "valore" ], "om_points": "value", "parameters": [ "id": "valore" ] } I wrote this script to print all of the JSON data: import json from pprint import pprint …

Read More
How do I write JSON data to a file?

I have JSON data stored in the variable data. I want to write this to a text file for testing so I don't have to grab the data from the server each time. Currently, I am trying this: obj = open(…

Read More