Fix #4192 bug with BaseModel.construct and aliased Fields (#4191)

* Fix a bug where BaseModel.construct would not appropriately respect field aliases

* Perhaps do not raise on construct and just apply the fix

* Fix quotes and remove check on allow_population_by_field_name

* Fix lint

* Fix lint, remove bad arg

* Black formatted

* Mmmm black formatter and single quotes linting, what a world

* Added change file

* PR feedback

Co-authored-by: Kyle Amos <kamos@seatgeek.com>

changes/4192-kylebamos.md

@@ -0,0 +1 @@
+Update BaseModel.construct to work with aliased Fields

pydantic/main.py

@@ -588,7 +588,9 @@ def construct(cls: Type['Model'], _fields_set: Optional['SetStr'] = None, **valu
         m = cls.__new__(cls)
         fields_values: Dict[str, Any] = {}
         for name, field in cls.__fields__.items():
-            if name in values:
+            if field.alt_alias and field.alias in values:
+                fields_values[name] = values[field.alias]
+            elif name in values:
                 fields_values[name] = values[name]
             elif not field.required:
                 fields_values[name] = field.get_default()

tests/test_aliases.py

@@ -1,5 +1,6 @@
 import re
-from typing import Any, List, Optional
+from contextlib import nullcontext as does_not_raise
+from typing import Any, ContextManager, List, Optional
 
 import pytest
 
@@ -345,3 +346,39 @@ class Model(BaseModel):
     m = Model(**data)
     assert m.empty_string_key == 123
     assert m.dict(by_alias=True) == data
+
+
+@pytest.mark.parametrize(
+    'use_construct, allow_population_by_field_name_config, arg_name, expectation',
+    [
+        [False, True, 'bar', does_not_raise()],
+        [False, True, 'bar_', does_not_raise()],
+        [False, False, 'bar', does_not_raise()],
+        [False, False, 'bar_', pytest.raises(ValueError)],
+        [True, True, 'bar', does_not_raise()],
+        [True, True, 'bar_', does_not_raise()],
+        [True, False, 'bar', does_not_raise()],
+        [True, False, 'bar_', does_not_raise()],
+    ],
+)
+def test_allow_population_by_field_name_config(
+    use_construct: bool,
+    allow_population_by_field_name_config: bool,
+    arg_name: str,
+    expectation: ContextManager,
+):
+    expected_value: int = 7
+
+    class Foo(BaseModel):
+        bar_: int = Field(..., alias='bar')
+
+        class Config(BaseConfig):
+            allow_population_by_field_name = allow_population_by_field_name_config
+
+    with expectation:
+        if use_construct:
+            f = Foo.construct(**{arg_name: expected_value})
+        else:
+            f = Foo(**{arg_name: expected_value})
+
+        assert f.bar_ == expected_value