1358328 - API Request is not returning JSON when it should.

Status: RESOLVED WONTFIX

(Webtools Graveyard :: DXR, defect)

Description

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

I'm trying to use DXR's JSON API in Treeherder, but I'm having some issues getting it to return JSON.

My request sets an Accept header of "application/json, text/plain, */*", which I would expect to prefer application/json, but instead I receive the html search results.

If I manually take out the "text/plain, */*", so my Accept header is just "application/json", I do get JSON results, but I'd rather not have to override Angular's $http framework to do that if I don't have to.


I'm not entirely sure why it's not sending JSON back for my request. As far as I can see from https://github.com/mozilla/dxr/blob/f3cc71a98975c99c34483fdc827489245b9387b9/dxr/app.py#L690 it should try to take the best option between 'application/json' and 'text/html' from the request's Accept header. Since the only one of those present is 'application/json', I'd assume `best` is 'application/json'.
The only thing I can think of is that since `request.accept_mimetypes['text/html']` is not defined, that greater-than check becomes false.

I'll put up a totally-untested patch to maybe fix this in a bit.

Comment 1

[Ed Morley [:emorley]]

accept_mimetypes comes from werkzeug:
https://github.com/pallets/werkzeug/blob/fbfa21e03286c05aa618138b20ee5823a3bac080/werkzeug/wrappers.py#L1325-L1329
https://github.com/pallets/werkzeug/blob/9c1ef73eb82f37a3b8e6b1f9f62685faae18b2f8/werkzeug/datastructures.py#L1726-L1750
https://github.com/pallets/werkzeug/blob/9c1ef73eb82f37a3b8e6b1f9f62685faae18b2f8/werkzeug/datastructures.py#L1753-L1805

Testing should be possible via:
```
from werkzeug.http import parse_accept_header
from werkzeug.datastructures import MIMEAccept

accept_mimetypes = parse_accept_header('application/json, text/plain, */*', MIMEAccept)
best = accept_mimetypes.best_match(...)
```

At a first glance I'd try making the greater than conditional a greater than or equal to.

Alternatively, perhaps this should just be using `accept_json()`?
https://github.com/pallets/werkzeug/blob/9c1ef73eb82f37a3b8e6b1f9f62685faae18b2f8/werkzeug/datastructures.py#L1803

Comment 2

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

Weird, I'm running this script:
```
from werkzeug.http import parse_accept_header
from werkzeug.datastructures import MIMEAccept

accept_mimetypes = parse_accept_header('application/json, text/plain, */*', MIMEAccept)
best = accept_mimetypes.best_match(['application/json', 'text/html'])

print accept_mimetypes
print best
print accept_mimetypes['application/json']
print accept_mimetypes['text/html']
print accept_mimetypes['text/plain']
```

Which then prints out:
```
text/plain,application/json,*/*
application/json
1
1
1
```

If I change accept_mimetypes like this:
```
accept_mimetypes = parse_accept_header('application/json', MIMEAccept)
```
It prints out:
```
application/json
application/json
1
0
0
```



And if I change it like:
```
accept_mimetypes = parse_accept_header('application/json, text/html', MIMEAccept)
```
It prints out:
```
text/html,application/json
application/json
1
1
0
```

So is it the wildcard at the end that's making this condition useless?

Comment 3

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

And indeed, if I change the accept_mimetypes line to be only '*/*', each of the checks returns '1'.

Comment 4

[Sylvestre Ledru [:Sylvestre]]

DXR is no longer available. Searchfox is now replacing it.
See meta bug 1669906 & https://groups.google.com/g/mozilla.dev.platform/c/jDRjrq3l-CY for more details.