from_dict customization per data class

Author: trojkat

dacite/core.py

@@ -96,7 +96,10 @@ def _build_value(type_: Type, data: Any, config: Config) -> Any:
     elif is_generic_collection(type_):
         data = _build_value_for_collection(collection=type_, data=data, config=config)
     elif cache(is_dataclass)(type_) and isinstance(data, Mapping):
-        data = from_dict(data_class=type_, data=data, config=config)
+        if hasattr(type_, "from_dict"):
+            data = type_.from_dict(data_class=type_, data=data, config=config)
+        else:
+            data = from_dict(data_class=type_, data=data, config=config)
     for cast_type in config.cast:
         if is_subclass(type_, cast_type):
             if is_generic_collection(type_):

tests/core/test_config.py

@@ -1,4 +1,5 @@
 from dataclasses import dataclass
+from datetime import date
 from enum import Enum
 from typing import Optional, List, Union
 
@@ -225,3 +226,35 @@ class Z:
     result = from_dict(Z, data, Config(strict_unions_match=True))
 
     assert result == Z(u=Y(f=1))
+
+
+def test_custom_from_dict_in_nested_data_class():
+    @dataclass
+    class X:
+        d: date
+        t: str
+
+        def from_dict(data_class, data, config):
+            data["t"] = "prefix {}".format(data["t"])
+            return from_dict(
+                data_class=data_class,
+                data=data,
+                config=Config(type_hooks={date: date.fromtimestamp}),
+            )
+
+    @dataclass
+    class Y:
+        d: date
+        x: X
+
+    config = Config(type_hooks={date: date.fromordinal})
+    data = {"d": 737790, "x": {"d": 1607511900.985121, "t": "abc"}}
+    result = from_dict(Y, data, config=config)
+
+    assert result == Y(
+        d=date(2020, 12, 31),
+        x=X(
+            d=date(2020, 12, 9),
+            t="prefix abc",
+        ),
+    )