add few ways to load config

sanic/config.py

@@ -1,7 +1,12 @@
 import os
-
+import errno
 import types
 
+try:
+    import ujson as json
+except ImportError:
+    import json
+
 SANIC_PREFIX = 'SANIC_'
 
 
@@ -97,12 +102,53 @@ class Config(dict):
             if key.isupper():
                 self[key] = getattr(obj, key)
 
+    def from_json(self, filename, silent=False):
+        """Updates the values in the config from a JSON file. This function
+        behaves as if the JSON object was a dictionary and passed to the
+        :meth:`from_mapping` function.
+
+        :param filename: the filename of the JSON file.  This can either be an
+                         absolute filename or a filename relative to the
+                         root path.
+        :param silent: set to ``True`` if you want silent failure for missing
+                       files.
+        """
+        try:
+            with open(filename) as json_file:
+                obj = json.loads(json_file.read())
+        except IOError as e:
+            if silent and e.errno in (errno.ENOENT, errno.EISDIR):
+                return False
+            e.strerror = 'Unable to load configuration file (%s)' % e.strerror
+            raise
+        return self.from_mapping(obj)
+
+    def from_mapping(self, *mapping, **kwargs):
+        """Updates the config like :meth:`update` ignoring items with non-upper
+        keys.
+        """
+        mappings = []
+        if len(mapping) == 1:
+            if hasattr(mapping[0], 'items'):
+                mappings.append(mapping[0].items())
+            else:
+                mappings.append(mapping[0])
+        elif len(mapping) > 1:
+            raise TypeError(
+                'expected at most 1 positional argument, got %d' % len(mapping)
+            )
+        mappings.append(kwargs.items())
+        for mapping in mappings:
+            for (key, value) in mapping:
+                if key.isupper():
+                    self[key] = value
+        return True
+
     def load_environment_vars(self):
+        """Looks for any SANIC_ prefixed environment variables and applies
+        them to the configuration if present.
+        """
         for k, v in os.environ.items():
-            """
-            Looks for any SANIC_ prefixed environment variables and applies
-            them to the configuration if present.
-            """
             if k.startswith(SANIC_PREFIX):
                 _, config_key = k.split(SANIC_PREFIX, 1)
                 self[config_key] = v

tests/test_config.py

@@ -16,18 +16,21 @@ def test_load_from_object():
     assert app.config.CONFIG_VALUE == 'should be used'
     assert 'not_for_config' not in app.config
 
+
 def test_auto_load_env():
     environ["SANIC_TEST_ANSWER"] = "42"
     app = Sanic()
     assert app.config.TEST_ANSWER == "42"
     del environ["SANIC_TEST_ANSWER"]
 
+
 def test_auto_load_env():
     environ["SANIC_TEST_ANSWER"] = "42"
     app = Sanic(load_env=False)
     assert getattr(app.config, 'TEST_ANSWER', None) == None
     del environ["SANIC_TEST_ANSWER"]
 
+
 def test_load_from_file():
     app = Sanic('test_load_from_file')
     config = b"""
@@ -74,6 +77,7 @@ def test_load_from_missing_envvar():
 def test_overwrite_exisiting_config():
     app = Sanic('test_overwrite_exisiting_config')
     app.config.DEFAULT = 1
+
     class Config:
         DEFAULT = 2
 
@@ -85,3 +89,22 @@ def test_missing_config():
     app = Sanic('test_missing_config')
     with pytest.raises(AttributeError):
         app.config.NON_EXISTENT
+
+
+def test_load_from_json():
+    app = Sanic('test_load_from_file')
+    config = b'{"VALUE": "some value"}'
+    with NamedTemporaryFile(mode='wb') as config_file:
+        config_file.write(config)
+        config_file.seek(0)
+        app.config.from_json(config_file.name)
+        assert 'VALUE' in app.config
+        assert app.config.VALUE == 'some value'
+
+
+def test_load_from_mapping():
+    app = Sanic('test_load_from_file')
+    config = {"VALUE": "some value"}
+    app.config.from_mapping(config)
+    assert 'VALUE' in app.config
+    assert app.config.VALUE == 'some value'