&stream=True fails for JSON results

[davidmegginson]

Adding &stream=True works for CSV and XML results, but not for JSON.

Confirmation links

The following queries return only 665 activities as of 2018-08-30, so size is not likely an issue.

[200 Success] http://datastore.iatistandard.org/api/1/access/activity.xml?recipient-country=GN&end-date__gt=2018-01-01&stream=True

[200 Success] http://datastore.iatistandard.org/api/1/access/activity.xml?recipient-country=GN&end-date__gt=2018-01-01&stream=True

[Redirects to following, then 500 Internal Server Error] http://datastore.iatistandard.org/api/1/access/activity.json?recipient-country=GN&end-date__gt=2018-01-01&stream=True

[500 Internal Server Error] http://datastore.iatistandard.org/api/1/access/activity.json?recipient-country=GN&end-date__gt=2018-01-01&stream=True

[davidmegginson]

To confirm that the issue isn't the result size, this query returns all of the existing JSON results with &limit=700:

http://datastore.iatistandard.org/api/1/access/activity.json?recipient-country=GN&end-date__gt=2018-01-01&limit=700

[andylolz]

The JSON serialiser uses the following wrapper around a query, to make it “quack like a pagination object”:

IATI-Datastore/iati_datastore/iatilib/frontend/api1.py

Lines 181 to 191 in 6fe7aba

	class Stream(object):
	"""
	Wrapper to make a query object quack like a pagination object
	"""
	limit = ''
	offset = ''
	def __init__(self, query):
	self.items = query
	self.total = query.count()

However, the query isn’t actually executed, so serialisation fails. I’ve sent a fix (#317).