Restore mutable item access to Properties

Resolves #1430.

CHANGES.txt

@@ -10,6 +10,9 @@ This is the first release candidate for 1.10.0.
 
 Changes:
 
+- Mutable item access to Feature, Geometry, and Properties instances has been
+  restored (reported in #1430). This usage should be avoided as instances of
+  these classes will be immutable in a future version.
 - The setup.cfg duplicates project configuration in pyproject.toml and has been
   removed.
 

fiona/model.py

@@ -139,12 +139,15 @@ def _props(self):
         }
 
     def __getitem__(self, item):
-        props = {
-            k: (dict(v) if isinstance(v, Object) else v)
-            for k, v in self._props().items()
-        }
-        props.update(**self._data)
-        return props[item]
+        if item in self._delegated_properties:
+            return getattr(self._delegate, item)
+        else:
+            props = {
+                k: (dict(v) if isinstance(v, Object) else v)
+                for k, v in self._props().items()
+            }
+            props.update(**self._data)
+            return props[item]
 
     def __iter__(self):
         props = self._props()

tests/test_model.py

@@ -342,3 +342,12 @@ def test_feature_repr():
         properties=Properties(a=1, foo="bar"),
     )
     assert repr(feat) == "fiona.Feature(geometry=fiona.Geometry(coordinates=[(0, 0), ...], type='LineString'), id='1', properties=fiona.Properties(a=1, foo='bar'))"
+
+
+def test_issue1430():
+    """__getitem__() returns property, not disconnected dict."""
+    feat = Feature(properties=Properties())
+    with pytest.warns(FionaDeprecationWarning, match="immutable"):
+        feat["properties"]["foo"] = "bar"
+    assert feat["properties"]["foo"] == "bar"
+    assert feat.properties["foo"] == "bar"