Passing a JSON object through POST using Python

Question

I'm trying to post a JSON object through a POST. I'm trying to do it as follows:

import json, urllib, urllib2

filename = 'test.json'
race_id = 2530
f = open(filename, 'r')
fdata = json.loads(f.read())
f.close()

prefix = 'localhost:8000'

count = 0
for points in fdata['positions'].iteritems():
    print '--' + str(count) + '--------'
    url = 'http://'+prefix+'/api/points'
    parameters = {'point_data': json.dumps(points), 'race_id': race_id}
    data = urllib.urlencode(parameters)
    print data
    request = urllib2.Request(url, data)
    response = urllib2.urlopen(request)
    count += 1
    break;

print 'Finished adding points'

The data is then received on the other end (I'm using Google App Engine) with:

point_data = json.load(self.request.get('point_data'))

But I get the following error:

ERROR    2010-06-30 15:08:05,367
__init__.py:391] 'unicode' object has no attribute 'read' Traceback (most
recent call last):   File
"/home/ian/workspace/google_appengine/google/appengine/ext/webapp/__init__.py",
line 513, in __call__
    handler.post(*groups)   File "/home/ian/workspace/codebase/track_builder/geo-api.py",
line 276, in post
    point_data = json.load(self.request.get('point_data'))
File
"/home/ian/workspace/google_appengine/lib/django/django/utils/simplejson/__init__.py",
line 208, in load
    return cls(encoding=encoding, **kw).decode(fp.read()) AttributeError: 'unicode' object has
no attribute 'read' INFO    
2010-06-30 15:08:05,376
dev_appserver.py:3266] "POST
/api/points HTTP/1.1" 500 -

Any ideas on how to fix this?

EDIT: As requested here is an example of the points:

(u'1276859700',
{
    u'24': {
        u'tempc': u'-22.7',
        u'gpsq': u'1',
        u'altm': u'65527',
        u'hd': u'112',
        u'hdop': u'0.93',
        u'bton': u'0',
        u'maxv': u'20.15',
        u'idit': u'1',
        u'satc': u'10',
        u'minv': u'20.15',
        u'lat': u'35.271993',
        u'btusr': u'0',
        u'lng': u'-121.845353',
        u'knots': u'7'
    },
    u'11': {
        u'tempc': u'13.0',
        u'gpsq': u'1',
        u'altm': u'65535',
        u'hd': u'130',
        u'hdop': u'0.84',
        u'bton': u'0',
        u'maxv': u'15.96',
        u'idit': u'1',
        u'satc': u'12',
        u'minv': u'15.88',
        u'lat': u'34.877815',
        u'btusr': u'0',
        u'lng': u'-121.386116',
        u'knots': u'8'
    }
}

EDIT 2: Thanks to Daniel Roseman and Nick Johnson who both caught my error. I've changed

point_data = json.loads(self.request.get('point_data'))

This has solved the error but, now I'm getting:

ERROR    2010-06-30 16:07:29,807 __init__.py:391] 'list' object has no attribute 'iteritems'
Traceback (most recent call last):
  File "/home/ian/workspace/google_appengine/google/appengine/ext/webapp/__init__.py", line 513, in __call__
    handler.post(*groups)
  File "/home/ian/workspace/codebase/track_builder/geo-api.py", line 255, in post
    for time, units in point_data.iteritems():
AttributeError: 'list' object has no attribute 'iteritems'
INFO     2010-06-30 16:07:29,816 dev_appserver.py:3266] "POST /api/points HTTP/1.1" 500 -

which relates to the following code:

class TrackPoint(webapp.RequestHandler):
    def post(self):
        point_data = json.loads(self.request.get('point_data'))
        race_id = self.request.get('race_id')
        added = []
        failed = []
        for time, units in point_data.iteritems():
            for unit, data in units.iteritems():
                ...

Any ideas on this one?

Since you haven't provided the actual points object, it's impossible to tell what it was encoded as or why it can't be encoded. You might want to print the points object so we can see what it is. — S.Lott
– S.Lott, Commented Jun 30, 2010 at 15:13
Can you re-paste the stacktrace as code, rather than a quote? SO's quoting has destroyed the original formatting, and it's nearly unreadable. — Nick Johnson
– Nick Johnson, Commented Jun 30, 2010 at 16:01

Daniel Roseman · Accepted Answer · 2010-06-30 15:51:52Z

31

It looks like self.request.get() is returning a unicode object rather than a file-like object. You could try using json.loads() instead of json.load().

answered Jun 30, 2010 at 15:51

Daniel Roseman

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2 Comments

Ian Burris Over a year ago

That seemed to fix the problem. Now I'm getting "AttributeError: 'list' object has no attribute 'iteritems'". Any ideas on this one? I've appended the necessary code in my question above.

Jake Sylvestre Over a year ago

just for clarification, the actual error here was load tries to open the file then load the data, where as loads() is for text.

Nick Johnson · Accepted Answer · 2010-06-30 16:02:34Z

4

json.load() expects a file object, but self.request.get returns the value of the parameter as a string.

The solution is easy: use json.loads.

Also, free tip: I presume from the name that you're bundling your own copy of the json library. App Engine actually includes a copy of simplejson that you can use - just do:

from django.utils import simplejson

answered Jun 30, 2010 at 16:02

Nick Johnson

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Comments

nguyên · Accepted Answer · 2011-06-17 02:42:22Z

1

first in js I recognize that json object must in STRING format (javascript file)

// using jquery, json2
var js = {"name":"nguyen","age":"1"};
$.post("/", {'data': JSON.stringify(js)}, function(ret){
        alert(ret);
    });

then in gae

from django.utils import simplejson as json

class PesonReq(webapp.RequestHandler):
    def post(self):
        t = json.loads(self.request.POST['data'])
        self.response.out.write(t['name'])

edited Jun 17, 2011 at 2:42

answered May 6, 2011 at 9:40

nguyên

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