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fix json emitter for empty response bodies #178

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Merged
demianbrecht merged 5 commits into from
Jul 22, 2025
Merged

fix json emitter for empty response bodies #178

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16da517
fix json emitter for empty response bodies
demianbrecht Jul 22, 2025
91dd39d
Update django_declarative_apis/resources/emitters.py
demianbrecht Jul 22, 2025
fe2c91f
pr feedback
demianbrecht Jul 22, 2025
81a9a8c
Merge branch 'main' into fix-empty-body-response
demianbrecht Jul 22, 2025
aef8eb9
changelog update, version bump
demianbrecht Jul 22, 2025
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18 changes: 11 additions & 7 deletions django_declarative_apis/resources/emitters.py
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Original file line number Diff line number Diff line change
Expand Up @@ -183,19 +183,23 @@ def decode(self, data):
def render(self, request):
cb = request.GET.get("callback", None)
assert cb is None, "JSONP Callbacks not suppoted"
seria = json.dumps(
self.decode(self.construct()),
cls=DjangoJSONEncoder,
ensure_ascii=False,
indent=4,
)
seria = self.decode(self.construct())
if isinstance(seria, list):
if len(seria) == 0 or (len(seria) == 1 and len(seria[0]) == 0):
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@bgrant bgrant Jul 22, 2025 •
edited
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I assume in some cases self.decode returns a tuple or something and that's the cause of the clause after the or? Is there a possibility of guessing this wrong and getting an IndexError on that seria[0]?

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@demianbrecht demianbrecht Jul 22, 2025

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The base case (len == 0) is a just in case. What we actually see with our current issue is [""]. No, if we have a list of length 1, it would always be accessible and have a length given it's a string (val.decode("utf8") in self.decode)

# the body is empty, no need to run json.dumps
return ""

# Callback
# TODO: do we care about JSONP?
# if cb and is_valid_jsonp_callback_value(cb):
# return '%s(%s)' % (cb, seria)

return seria
return json.dumps(
seria,
cls=DjangoJSONEncoder,
ensure_ascii=False,
indent=4,
)


Emitter.register("json", JSONEmitter, "application/json; charset=utf-8")
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5 changes: 5 additions & 0 deletions tests/resources/test_emitters.py
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Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,11 @@ def test_decode(self):
resp = em.render(django.test.RequestFactory().get("/"))
self.assertEqual(json.loads(resp), ["foo", "bar"])

def test_decode_empty_list(self):
em = emitters.JSONEmitter([""], lambda: None)
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@lukka5 lukka5 Jul 22, 2025

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for completeness don't we want another test with a truly empty list?

resp = em.render(django.test.RequestFactory().get("/"))
self.assertEqual(resp, "")


class DjangoEmitterTestCase(unittest.TestCase):
def test_render_http_response_succes(self):
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