Proof of concept RESTful Python server (using web.py) + testing with cURL

Question

I am in the process of writing a proof of concept RESTful server using web.py

Here is the script:

#!/usr/bin/env python
import web
import json


def notfound():
    #return web.notfound("Sorry, the page you were looking for was not found.")
    return json.dumps({'ok':0, 'errcode': 404})

def internalerror():
    #return web.internalerror("Bad, bad server. No donut for you.")
    return json.dumps({'ok':0, 'errcode': 500})


urls = (
    '/(.*)', 'handleRequest',
)


app = web.application(urls, globals())
app.notfound = notfound
app.internalerror = internalerror


class handleRequest:
    def GET(self, method_id):
        if not method_id: 
            return web.notfound()
        else:
            return json.dumps({'ok': method_id})

    def POST(self):
        i = web.input()
        data = web.data() # you can get data use this method
        print data
        pass

if __name__ == "__main__":
    app.run()

I can send GET requests ok, however when I try to send a POST request, I get an internal error. At the moment, I am not sure whether the error is due to cURL not sending the POST correctly (highly unlikely), or whether my server is not correctly implemented (more likely).

This is the command I use to send the POST request:

curl -i -H "Accept: application/json" -X POST -d "value":"30","type":"Tip 3","targetModule":"Target 3","active":true http://localhost:8080/xx/xxx/xxxx

Here is the server response:

me@localhost:~curl -i -H "Accept: application/json" -X POST -d "value":"30","type":"Tip 3","targetModule":"Target 3","active":true http://localhost:8080/xx/xxx/xxxx
HTTP/1.1 500 Internal Server Error
Content-Length: 1382
Content-Type: text/plain

Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/wsgiserver/__init__.py", line 1245, in communicate
    req.respond()
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/wsgiserver/__init__.py", line 775, in respond
    self.server.gateway(self).respond()
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/wsgiserver/__init__.py", line 2018, in respond
    response = self.req.server.wsgi_app(self.env, self.start_response)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/httpserver.py", line 270, in __call__
    return self.app(environ, xstart_response)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/httpserver.py", line 238, in __call__
    return self.app(environ, start_response)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/application.py", line 277, in wsgi
    result = self.handle_with_processors()
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/application.py", line 247, in handle_with_processors
    return process(self.processors)
  File "/usr/local/lib/python2.6/dist-packages/web.py-0.36-py2.6.egg/web/application.py", line 244, in process
    raise self.internalerror()
TypeError: exceptions must be old-style classes or derived from BaseException, not str

What is the cause of the error - and how may I fix it?

Answer 1

There are a few issues here.

1) POST takes 2 arguments (like GET), self and the resource (method_id is fine)
2) When you're making a POST request you're setting "Content-Type" and not "Accept"
3) Your JSON isn't in quotes as a string

If you change your POST to (self, method_id) the following should work:

curl -i -H "Content-Type: application/json" -X POST -d '{"value":"30","type":"Tip 3","targetModule":"Target 3","active":true}' http://127.0.0.1:8080

You should also wrap the block in a try/except to catch errors and do something useful with them:

def POST(self,method_id):
    try:
        i = web.input()
        data = web.data() # you can get data use this method
        return
    except Error(e):
        print e