improve smart_union

pydantic · Sep 5, 2021 · eeaca09 · eeaca09
1 parent f8c0c56
commit eeaca09
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Showing 2 changed files with 19 additions and 14 deletions.
diff --git a/pydantic/fields.py b/pydantic/fields.py
@@ -956,7 +956,8 @@ def _validate_singleton(
                         if isinstance(v, field.outer_type_):
                             return v, None
                     except TypeError:
-                        pass
+                        if isinstance(v, get_origin(field.outer_type_)):
+                            return v, None
 
             # 1st pass by default or 3rd pass with `smart_union` enabled:
             # check if the value can be coerced into one of the Union types

diff --git a/tests/test_types.py b/tests/test_types.py
@@ -2936,29 +2936,33 @@ class Config:
 
 
 def test_default_union_compound_types():
-    class DefaultModel(BaseModel):
+    class Model(BaseModel):
         values: Union[Dict[str, str], List[str]]
 
-    assert DefaultModel(values={'L': '1'}).dict() == {'values': {'L': '1'}}
-    assert DefaultModel(values=['L1']).dict() == {'values': {'L': '1'}}  # dict(['L1']) == {'L': '1'}
+    assert Model(values={'L': '1'}).dict() == {'values': {'L': '1'}}
+    assert Model(values=['L1']).dict() == {'values': {'L': '1'}}  # dict(['L1']) == {'L': '1'}
 
 
 def test_smart_union_compound_types():
-    """For now, `smart_union` does not support well compound types"""
-
-    class DefaultModel(BaseModel):
+    class Model(BaseModel):
         values: Union[Dict[str, str], List[str]]
 
         class Config:
             smart_union = True
 
-    assert DefaultModel(values={'L': '1'}).dict() == {'values': {'L': '1'}}
-    assert DefaultModel(values=['L1']).dict() == {
-        'values': {'L': '1'}
-    }  # should be `['L1']` once `smart_union` is improved
-    assert DefaultModel(values=('L1',)).dict() == {
-        'values': {'L': '1'}
-    }  # expected! (still coerce as tuple is not a list)
+    assert Model(values={'L': '1'}).dict() == {'values': {'L': '1'}}
+    assert Model(values=['L1']).dict() == {'values': ['L1']}
+    assert Model(values=('L1',)).dict() == {'values': {'L': '1'}}  # expected! (still coerce as tuple is not a list)
+
+
+def test_smart_union_compouned_types_edge_case():
+    """For now, `smart_union` does not support well compound types"""
+
+    class Model(BaseModel):
+        x: Union[List[str], List[int]]
+
+    # should consider [1, 2] valid and not coerce once `smart_union` is improved
+    assert Model(x=[1, 2]).x == ['1', '2']
 
 
 @pytest.mark.parametrize(