From 46f83665ef74880bbc4a1c1f17ccededa7aaa939 Mon Sep 17 00:00:00 2001
From: David Lord <davidism@gmail.com>
Date: Mon, 24 Apr 2017 10:09:50 -0700
Subject: [PATCH] clean up blueprint json support add changelog for #1898

---
 CHANGES               |  3 +++
 flask/blueprints.py   |  4 ++--
 flask/json.py         | 24 ++++++++++++++----------
 tests/test_helpers.py | 16 +++++++++++-----
 4 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/CHANGES b/CHANGES
index d7f15d66..ae592ba8 100644
--- a/CHANGES
+++ b/CHANGES
@@ -27,8 +27,11 @@ Major release, unreleased
 - ``MethodView`` can inherit method handlers from base classes. (`#1936`_)
 - Errors caused while opening the session at the beginning of the request are
   handled by the app's error handlers. (`#2254`_)
+- Blueprints gained ``json_encoder`` and ``json_decoder`` attributes to
+  override the app's encoder and decoder. (`#1898`_)
 
 .. _#1489: https://github.com/pallets/flask/pull/1489
+.. _#1898: https://github.com/pallets/flask/pull/1898
 .. _#1936: https://github.com/pallets/flask/pull/1936
 .. _#2017: https://github.com/pallets/flask/pull/2017
 .. _#2223: https://github.com/pallets/flask/pull/2223
diff --git a/flask/blueprints.py b/flask/blueprints.py
index 62675204..57d77512 100644
--- a/flask/blueprints.py
+++ b/flask/blueprints.py
@@ -90,10 +90,10 @@ class Blueprint(_PackageBoundObject):
     _got_registered_once = False
 
     #: Blueprint local JSON decoder class to use.
-    # Set to None to use the :class:`~flask.app.Flask.json_encoder`.
+    #: Set to ``None`` to use the app's :class:`~flask.app.Flask.json_encoder`.
     json_encoder = None
     #: Blueprint local JSON decoder class to use.
-    # Set to None to use the :class:`~flask.app.Flask.json_decoder`.
+    #: Set to ``None`` to use the app's :class:`~flask.app.Flask.json_decoder`.
     json_decoder = None
 
     def __init__(self, name, import_name, static_folder=None,
diff --git a/flask/json.py b/flask/json.py
index 77b5fce1..bf8a8843 100644
--- a/flask/json.py
+++ b/flask/json.py
@@ -92,13 +92,16 @@ class JSONDecoder(_json.JSONDecoder):
 def _dump_arg_defaults(kwargs):
     """Inject default arguments for dump functions."""
     if current_app:
-        bp = current_app.blueprints.get(request.blueprint,
-                                        None) if has_request_context() else None
-        kwargs.setdefault('cls',
-                          bp.json_encoder if bp and bp.json_encoder
-                          else current_app.json_encoder)
+        bp = current_app.blueprints.get(request.blueprint) if request else None
+        kwargs.setdefault(
+            'cls',
+            bp.json_encoder if bp and bp.json_encoder
+                else current_app.json_encoder
+        )
+
         if not current_app.config['JSON_AS_ASCII']:
             kwargs.setdefault('ensure_ascii', False)
+
         kwargs.setdefault('sort_keys', current_app.config['JSON_SORT_KEYS'])
     else:
         kwargs.setdefault('sort_keys', True)
@@ -108,11 +111,12 @@ def _dump_arg_defaults(kwargs):
 def _load_arg_defaults(kwargs):
     """Inject default arguments for load functions."""
     if current_app:
-        bp = current_app.blueprints.get(request.blueprint,
-                                        None) if has_request_context() else None
-        kwargs.setdefault('cls',
-                          bp.json_decoder if bp and bp.json_decoder
-                          else current_app.json_decoder)
+        bp = current_app.blueprints.get(request.blueprint) if request else None
+        kwargs.setdefault(
+            'cls',
+            bp.json_decoder if bp and bp.json_decoder
+                else current_app.json_decoder
+        )
     else:
         kwargs.setdefault('cls', JSONDecoder)
 
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index c811e1b7..325713c0 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -271,30 +271,36 @@ class TestJSON(object):
         class X(object):
             def __init__(self, val):
                 self.val = val
+
         class MyEncoder(flask.json.JSONEncoder):
             def default(self, o):
                 if isinstance(o, X):
                     return '<%d>' % o.val
+
                 return flask.json.JSONEncoder.default(self, o)
+
         class MyDecoder(flask.json.JSONDecoder):
             def __init__(self, *args, **kwargs):
                 kwargs.setdefault('object_hook', self.object_hook)
                 flask.json.JSONDecoder.__init__(self, *args, **kwargs)
+
             def object_hook(self, obj):
                 if len(obj) == 1 and '_foo' in obj:
                     return X(obj['_foo'])
+
                 return obj
 
-        blue = flask.Blueprint('blue', __name__)
-        blue.json_encoder = MyEncoder
-        blue.json_decoder = MyDecoder
-        @blue.route('/bp', methods=['POST'])
+        bp = flask.Blueprint('bp', __name__)
+        bp.json_encoder = MyEncoder
+        bp.json_decoder = MyDecoder
+
+        @bp.route('/bp', methods=['POST'])
         def index():
             return flask.json.dumps(flask.request.get_json()['x'])
 
         app = flask.Flask(__name__)
         app.testing = True
-        app.register_blueprint(blue)
+        app.register_blueprint(bp)
 
         c = app.test_client()
         rv = c.post('/bp', data=flask.json.dumps({