Add ModelBase.from_prepended_mapping

Author: bdowning

sql_athame/dataclasses.py

@@ -313,6 +313,16 @@ def from_mapping(cls: type[T], mapping: Mapping[str, Any], /) -> T:
         cls.from_mapping = from_mapping_fn  # type: ignore
         return from_mapping_fn(mapping)
 
+    @classmethod
+    def from_prepended_mapping(
+        cls: type[T], mapping: Mapping[str, Any], prepend: str
+    ) -> T:
+        filtered_dict: dict[str, Any] = {}
+        for k, v in mapping.items():
+            if k.startswith(prepend):
+                filtered_dict[k[len(prepend) :]] = v
+        return cls.from_mapping(filtered_dict)
+
     @classmethod
     def ensure_model(cls: type[T], row: Union[T, Mapping[str, Any]]) -> T:
         if isinstance(row, cls):

tests/test_dataclasses.py

@@ -210,3 +210,7 @@ class Test(ModelBase, table_name="table"):
     assert Test.from_mapping({"foo": "FOO", "bar": "BAR"}) == Test("foo", "BAR")
     # make sure the monkey patching didn't screw things up
     assert Test.from_mapping({"foo": "FOO", "bar": "BAR"}) == Test("foo", "BAR")
+
+    assert Test.from_prepended_mapping(
+        {"p_foo": "FOO", "p_bar": "BAR", "foo": "not foo", "other": "other"}, "p_"
+    ) == Test("foo", "BAR")