AttributeError: 'str' object has no attribute 'items'

In the following code:

#!/usr/local/bin/python
import json

APPLICATION_NAME = 'cc9226315643df89-36bf02429075329d0ba36748360d050c'

HEADERS1 = json.dumps(dict(Destination = u"/api/af/latest/applications/%s/rulesets" % (APPLICATION_NAME)))
print "Headers1 is %s" % (HEADERS1)
HEADERS2 = {'Destination': '/api/af/latest/applications/%s/rulesets' % (APPLICATION_NAME)}
print "Headers2 is %s" % (HEADERS2)

I get the following output:

Headers1 is {"Destination": "/api/af/latest/applications/cc9226315643df89-36bf02429075329d0ba36748360d050c/rulesets"}
Headers2 is {'Destination': '/api/af/latest/applications/cc9226315643df89-36bf02429075329d0ba36748360d050c/rulesets'}

but when I try to use either HEADER1 or HEADER2 in a REST call using requests(), I get very different results:

SERVER_URL = 'http://1.1.33.109:8087%s' % (APP_PATH)
REQ_DATA = None
print "Headers are: ", HEADERS
print "SERVER_URL is: ", SERVER_URL
print "Request Data is:", REQ_DATA
print ""

RESPONSE = requests.request(
    'MOVE', 
    SERVER_URL, 
    auth = ('admin', 'admin'), 
    verify = False, 
    data = REQ_DATA,
    headers = HEADERS1 )     #<-- If I use HEADER1 it breaks, if I use HEADER2 it works
print "Move Ruleset back to the Application RESULT: %s\n" % (RESPONSE)

I get the following with HEADER1:

Traceback (most recent call last):
   File "./myrest.py", line 234, in <module>
     headers = HEADERS1 )
   File "/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/requests/api.py", line 44, in request
     return session.request(method=method, url=url, **kwargs)
   File "/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/requests/sessions.py", line 324, in request
     prep = req.prepare()
   File "/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/requests/models.py", line 223, in prepare
     p.prepare_headers(self.headers)
   File "/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/requests/models.py", line 340, in prepare_headers
     headers = dict((name.encode('ascii'), value) for name, value in headers.items())
AttributeError: 'str' object has no attribute 'items'

If I use HEADER2 it executes cleanly:

Move Ruleset back to the Application RESULT: Response [200]

Can anyone explain what the differences are?

You are passing in a string; headers can't ever be a JSON encoded string, it is always a Python dictionary.

The print results are deceptive; JSON encoded objects look a lot like Python dictionary representations but they are far from the same thing.

The requests API clearly states that headers must be a dictionary:

• headers – (optional) Dictionary of HTTP Headers to send with the Request.

JSON data is something you'd send as content to another server, not something you'd use to communicate with a Python API.