user_context is overwritten when Sentry(app) called after @before_request

[iffy]

If you initialize raven.contrib.flask.Sentry after a Flask before_request has been defined (in which sentry.user_context is used), the user context is destroyed when sending errors.

For instance, in the code below the user context sent to Sentry only has an ip address. But if you uncomment "Option A" and comment out the "Option B", the user context contains email=bob@bob.com (and the other items).

from flask import Flask
from raven.contrib.flask import Sentry

app = Flask(__name__)

# Option A
# sentry = Sentry(app)
# message = 'Option A'

@app.before_request
def before_request():
    sentry.user_context({
        'ip_address': '1.2.3.4',
        'email': 'bob@bob.com',
        'username': 'someguy',
        'id': '1238923',
    })
    sentry.extra_context({
        'goo': 'bar',
        'ip_address': '1.2.3.4',
        'email': 'bob@bob.com',
        'username': 'someguy',
        'id': '1238923',
    })

# Option B
sentry = Sentry(app)
message = 'Option B'

@app.route('/')
def index():
    raise Exception(message)

app.run(debug=True)

I think it's because get_user_info in this spot returns None and merging None overwrites existing values:

>>> from raven.context import Context
>>> c = Context()
>>> c.merge({'user': {'foo': 'bar'}})
>>> c
<Context: {'user': {'foo': 'bar'}}>
>>> c.merge({'user': None})
>>> c
<Context: {'user': None}>

So maybe the fix is to have Context.merge treat Nones as {}. Or maybe get_user_info should return {} instead of None.

Or maybe this:

diff --git a/raven/contrib/flask.py b/raven/contrib/flask.py
index a973344..6014c2c 100644
--- a/raven/contrib/flask.py
+++ b/raven/contrib/flask.py
@@ -221,7 +221,7 @@ class Sentry(object):
         except Exception as e:
             self.client.logger.exception(to_unicode(e))
         try:
-            self.client.user_context(self.get_user_info(request))
+            self.client.user_context(self.get_user_info(request) or {})
         except Exception as e:
             self.client.logger.exception(to_unicode(e))

[iffy]

Any update on this?

[iffy]

Is my suggested fix not a good one? Or are you waiting for me to file a PR?

[mitsuhiko]

I am not sure if that is actually the correct fix here. For the moment I think it makes sense to put this into the docs (that you need to initialize this early together with the rest of the app).