Merge pull request #3398 from pgjones/toml

Support loading configuration from text files

CHANGES.rst

@@ -7,6 +7,9 @@ Unreleased
 
 -   Add :meth:`sessions.SessionInterface.get_cookie_name` to allow
     setting the session cookie name dynamically. :pr:`3369`
+-   Add :meth:`Config.from_file` to load config using arbitrary file
+    loaders, such as ``toml.load`` or ``json.load``.
+    :meth:`Config.from_json` is deprecated in favor of this. :pr:`3398`
 
 
 Version 1.1.2

docs/config.rst

@@ -393,8 +393,8 @@ The following configuration values are used internally by Flask:
     Added :data:`MAX_COOKIE_SIZE` to control a warning from Werkzeug.
 
 
-Configuring from Files
+Configuring from Python Files
-----------------------
+-----------------------------
 
 Configuration becomes more useful if you can store it in a separate file,
 ideally located outside the actual application package. This makes
@@ -441,6 +441,26 @@ complete reference, read the :class:`~flask.Config` object's
 documentation.
 
 
+Configuring from Data Files
+---------------------------
+
+It is also possible to load configuration from a file in a format of
+your choice using :meth:`~flask.Config.from_file`. For example to load
+from a TOML file:
+
+.. code-block:: python
+
+    import toml
+    app.config.from_file("config.toml", load=toml.load)
+
+Or from a JSON file:
+
+.. code-block:: python
+
+    import json
+    app.config.from_file("config.json", load=json.load)
+
+
 Configuring from Environment Variables
 --------------------------------------
 

src/flask/config.py

@@ -11,10 +11,10 @@
 import errno
 import os
 import types
+import warnings
 
 from werkzeug.utils import import_string
 
-from . import json
 from ._compat import iteritems
 from ._compat import string_types
 
@@ -176,31 +176,63 @@ class Config(dict):
             if key.isupper():
                 self[key] = getattr(obj, key)
 
-    def from_json(self, filename, silent=False):
+    def from_file(self, filename, load, silent=False):
-        """Updates the values in the config from a JSON file. This function
+        """Update the values in the config from a file that is loaded
-        behaves as if the JSON object was a dictionary and passed to the
+        using the ``load`` parameter. The loaded data is passed to the
-        :meth:`from_mapping` function.
+        :meth:`from_mapping` method.
 
-        :param filename: the filename of the JSON file.  This can either be an
+        .. code-block:: python
-                         absolute filename or a filename relative to the
-                         root path.
-        :param silent: set to ``True`` if you want silent failure for missing
-                       files.
 
-        .. versionadded:: 0.11
+            import toml
+            app.config.from_file("config.toml", load=toml.load)
+
+        :param filename: The path to the data file. This can be an
+            absolute path or relative to the config root path.
+        :param load: A callable that takes a file handle and returns a
+            mapping of loaded data from the file.
+        :type load: ``Callable[[Reader], Mapping]`` where ``Reader``
+            implements a ``read`` method.
+        :param silent: Ignore the file if it doesn't exist.
+
+        .. versionadded:: 1.2
         """
         filename = os.path.join(self.root_path, filename)
 
         try:
-            with open(filename) as json_file:
+            with open(filename) as f:
-                obj = json.loads(json_file.read())
+                obj = load(f)
         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_json(self, filename, silent=False):
+        """Update the values in the config from a JSON file. The loaded
+        data is passed to the :meth:`from_mapping` method.
+
+        :param filename: The path to the JSON file. This can be an
+            absolute path or relative to the config root path.
+        :param silent: Ignore the file if it doesn't exist.
+
+        .. deprecated:: 1.2
+            Use :meth:`from_file` with :meth:`json.load` instead.
+
+        .. versionadded:: 0.11
+        """
+        warnings.warn(
+            "'from_json' is deprecated and will be removed in 2.0."
+            " Use 'from_file(filename, load=json.load)' instead.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        from .json import load
+
+        return self.from_file(filename, load, silent=silent)
+
     def from_mapping(self, *mapping, **kwargs):
         """Updates the config like :meth:`update` ignoring items with non-upper
         keys.

tests/test_config.py

@@ -6,6 +6,7 @@
     :copyright: 2010 Pallets
     :license: BSD-3-Clause
 """
+import json
 import os
 import textwrap
 from datetime import timedelta
@@ -27,7 +28,7 @@ def common_object_test(app):
     assert "TestConfig" not in app.config
 
 
-def test_config_from_file():
+def test_config_from_pyfile():
     app = flask.Flask(__name__)
     app.config.from_pyfile(__file__.rsplit(".", 1)[0] + ".py")
     common_object_test(app)
@@ -39,10 +40,10 @@ def test_config_from_object():
     common_object_test(app)
 
 
-def test_config_from_json():
+def test_config_from_file():
     app = flask.Flask(__name__)
     current_dir = os.path.dirname(os.path.abspath(__file__))
-    app.config.from_json(os.path.join(current_dir, "static", "config.json"))
+    app.config.from_file(os.path.join(current_dir, "static", "config.json"), json.load)
     common_object_test(app)
 
 
@@ -116,16 +117,16 @@ def test_config_missing():
     assert not app.config.from_pyfile("missing.cfg", silent=True)
 
 
-def test_config_missing_json():
+def test_config_missing_file():
     app = flask.Flask(__name__)
     with pytest.raises(IOError) as e:
-        app.config.from_json("missing.json")
+        app.config.from_file("missing.json", load=json.load)
     msg = str(e.value)
     assert msg.startswith(
         "[Errno 2] Unable to load configuration file (No such file or directory):"
     )
     assert msg.endswith("missing.json'")
-    assert not app.config.from_json("missing.json", silent=True)
+    assert not app.config.from_file("missing.json", load=json.load, silent=True)
 
 
 def test_custom_config_class():