Allow exceptions to always be raised on view errors

The current behavior to swallow exceptions makes it really hard to
track down bugs in the system. I would recommend to make this the default,
but I don’t want to impose so here’s a solution which requires the
config option `ADMIN_RAISE_ON_VIEW_EXCEPTION` to be set.

flask_admin/contrib/sqla/view.py

@@ -10,7 +10,7 @@ from sqlalchemy.exc import IntegrityError
 from sqlalchemy.sql.expression import cast
 from sqlalchemy import Unicode
 
-from flask import flash
+from flask import current_app, flash
 
 from flask_admin._compat import string_types, text_type
 from flask_admin.babel import gettext, ngettext, lazy_gettext
@@ -996,6 +996,9 @@ class ModelView(BaseModelView):
     # Error handler
     def handle_view_exception(self, exc):
         if isinstance(exc, IntegrityError):
+            if current_app.config.get('ADMIN_RAISE_ON_VIEW_EXCEPTION'):
+                raise
+            else:
                 flash(gettext('Integrity error. %(message)s', message=text_type(exc)), 'error')
             return True
 

flask_admin/model/base.py

@@ -7,8 +7,8 @@ from math import ceil
 
 from werkzeug import secure_filename
 
-from flask import (request, redirect, flash, abort, json, Response,
-                   get_flashed_messages, stream_with_context)
+from flask import (current_app, request, redirect, flash, abort, json,
+                   Response, get_flashed_messages, stream_with_context)
 from jinja2 import contextfunction
 try:
     import tablib
@@ -1441,6 +1441,9 @@ class BaseModelView(BaseView, ActionsMixin):
             flash(as_unicode(exc), 'error')
             return True
 
+        if current_app.config.get('ADMIN_RAISE_ON_VIEW_EXCEPTION'):
+            raise
+
         if self._debug:
             raise