Improved error handling

[mfield]

When a request to Sift fails, I want to know if I should retry it. The only way for me to do that right now is to parse the string representation of a sift.client.ApiException based on error messages we've already seen.

For example, this error is retryable:

ApiException: https://api.siftscience.com/v205/events returned non-2XX http status code 400 with error message: Rate limited; too many events have been received in a short period of time. Contact us if you have questions.

But this one is not:

ApiException: https://api.siftscience.com/v205/events returned non-2XX http status code 400 with error message: Invalid field value(s) for fields: $.$session_id. Please check the documentation for valid field values.

Lower level errors that may get raised from the Requests library are also converted to the same sift.client.ApiException, so I lose out on the whole taxonomy of errors in http://docs.python-requests.org/en/master/_modules/requests/exceptions/. I think in our case we'd lean toward an at least once approach rather than an at most once approach so maybe the difference between a ConnectTimeout and a ReadTimeout isn't that huge? It would be nice to have the information available to make a more deliberate decision though.

The sift-ruby approach of putting the response as an attribute of the error seems pretty good. It would give me access to these error codes that are pretty well documented https://siftscience.com/developers/docs/python/apis-overview/core-topics/error-reference.

[ehrmann]

For parameter validation, we should switch to ValueError.

I agree that we need to do a better job signaling if the request should be retried. It might be better to have a field on ApiException like retriable or even just http_status_code and sift_status_code so that we're not as coupled to requests for http, but I'm not opposed to exposing the response in the exception.

[mfield]

Looks like API3 errors may not be parsed correctly. I see this in the sift console

"{\"error\":\"too_many_requests\",\"description\":\"You've sent too many requests to this API recently. Try again later.\"}"

on my end it looks like the description field is not understood as the error message, all I see is

ApiException: https://api3.siftscience.com/v3/accounts/5b2c18de4f0c58535cc39b7c/users/498742366996267018/decisions returned non-2XX http status code 400

[ehrmann]

I think that's just the exception message from requests; we don't parse the response.

[mfield]

I do get more informative error messages from the events api. I'm not sure if it's api/api3 or labels/decisions that explains why.

https://github.com/SiftScience/sift-python/blob/e55afff4fd787d7d56effef013e59e61f79f8444/sift/client.py#L809-L810

[ehrmann]

Oh, there's missing handling in this block: https://github.com/SiftScience/sift-python/blob/e55afff4fd787d7d56effef013e59e61f79f8444/sift/client.py#L797-L802

There should be if 'description' in self.body: (or something similar)

[ehrmann]

We changed the ApiException class to include a lot more metadata.