Passing non-string header values causes request to silently fail

[edam]

Passing headers that contain non-string values, e.g.:

headers = {
    'X-MeaningOfLife': 42, # not a string
}

Causes the request to fail and, although response is None, no exception is thrown and there is no other sign that the request was not made (that I'm aware of).

[spyoungtech]

Exceptions that occur with AsyncRequests are caught and stored in an exception attribute.

>>> headers = {'foo': 42}
>>> req = grequests.get('https://httpbin.org', headers=headers)
>>> req.send()
<grequests.AsyncRequest object at 0x000001E23EC567F0>
>>> req.response
>>> req.exception # None
InvalidHeader("Value for header {foo: 42} must be of type str or bytes, not <class 'int'>",)

If you're using grequests.map to send the requests, you should use the exception_handler argument to deal with errors.

>>> def exception_handler(req, ex):
...     print(ex)
...     return locals()
...
>>> grequests.map([grequests.get('https://httpbin.org', headers=headers)], exception_handler=exception_handler)
Value for header {foo: 42} must be of type str or bytes, not <class 'int'>
[{'ex': InvalidHeader("Value for header {foo: 42} must be of type str or bytes, not <class 'int'>",), 'req': <grequests.AsyncRequest object at 0x000001E23F99A470>}]

Hope that helps.