Fix missing Field import with multiple aliases on required fields (#2992)

Author: koxudaxi

src/datamodel_code_generator/model/pydantic/base_model.py

@@ -297,10 +297,6 @@ def annotated(self) -> str | None:
     @property
     def imports(self) -> tuple[Import, ...]:
         """Get all required imports including Field if needed."""
-        # Fast path: skip expensive self.field check for simple required fields
-        if self.required and not self.nullable and not self.alias and self.constraints is None and not self.extras:
-            return super().imports
-
         if self.field:
             return chain_as_tuple(super().imports, (IMPORT_FIELD,))
         return super().imports

tests/data/aliases/multiple_aliases_required.json

@@ -0,0 +1,4 @@
+{
+  "name": ["full_name", "customer_name"],
+  "email": ["email_address", "mail"]
+}

tests/data/expected/dynamic_models/multiple_aliases_required.json

@@ -0,0 +1,5 @@
+{
+  "Customer": {
+    "full_name": "John"
+  }
+}

tests/data/expected/dynamic_models/multiple_aliases_required_code.py

@@ -0,0 +1,13 @@
+# generated by datamodel-codegen:
+#   filename:  <dict>
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import AliasChoices, BaseModel, Field
+
+
+class Customer(BaseModel):
+    full_name: str = Field(
+        ..., validation_alias=AliasChoices('name', 'full_name', 'customer_name')
+    )

tests/data/expected/main/jsonschema/jsonschema_multiple_aliases_required_pydantic_v2.py

@@ -0,0 +1,16 @@
+# generated by datamodel-codegen:
+#   filename:  multiple_aliases_required.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import AliasChoices, BaseModel, Field
+
+
+class Root(BaseModel):
+    full_name: str = Field(
+        ..., validation_alias=AliasChoices('name', 'full_name', 'customer_name')
+    )
+    email_address: str = Field(
+        ..., validation_alias=AliasChoices('email', 'email_address', 'mail')
+    )

tests/data/jsonschema/multiple_aliases_required.json

@@ -0,0 +1,10 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Root",
+  "type": "object",
+  "properties": {
+    "name": { "type": "string" },
+    "email": { "type": "string" }
+  },
+  "required": ["name", "email"]
+}

tests/main/jsonschema/test_main_jsonschema.py

@@ -8495,3 +8495,19 @@ def test_main_jsonschema_dynamic_ref_in_defs_pydantic_v2(output_file: Path) -> N
         expected_file="dynamic_ref_in_defs_pydantic_v2.py",
         extra_args=["--output-model-type", "pydantic_v2.BaseModel"],
     )
+
+
+def test_main_jsonschema_multiple_aliases_required_pydantic_v2(output_file: Path) -> None:
+    """Test multiple aliases with AliasChoices on required fields for Pydantic v2. (#2989)."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "multiple_aliases_required.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+        extra_args=[
+            "--aliases",
+            str(ALIASES_DATA_PATH / "multiple_aliases_required.json"),
+            "--output-model-type",
+            "pydantic_v2.BaseModel",
+        ],
+    )

tests/main/test_dynamic_models.py

@@ -459,6 +459,37 @@ def test_execute_multi_module_no_models() -> None:
     assert models == {}
 
 
+def test_multiple_aliases_required_field() -> None:
+    """Test dynamic models with multiple aliases on required fields. (#2989)."""
+    schema = make_object_schema({"name": {"type": "string"}}, required=["name"])
+    config = GenerateConfig(
+        input_file_type=InputFileType.JsonSchema,
+        output_model_type=DataModelType.PydanticV2BaseModel,
+        aliases={"name": ["full_name", "customer_name"]},
+        class_name="Customer",
+    )
+    assert_dynamic_models(
+        schema,
+        {"Customer": {"name": "John"}},
+        EXPECTED_PATH / "multiple_aliases_required.json",
+        config=config,
+    )
+
+
+def test_multiple_aliases_required_field_code_output() -> None:
+    """Test generated code includes Field import with multiple aliases on required fields. (#2989)."""
+    schema = make_object_schema({"name": {"type": "string"}}, required=["name"])
+    config = GenerateConfig(
+        input_file_type=InputFileType.JsonSchema,
+        output_model_type=DataModelType.PydanticV2BaseModel,
+        aliases={"name": ["full_name", "customer_name"]},
+        class_name="Customer",
+    )
+    result = generate(input_=schema, config=config)
+    assert isinstance(result, str)
+    assert_output(result, EXPECTED_PATH / "multiple_aliases_required_code.py")
+
+
 def test_execute_multi_module_enum_only() -> None:
     """Test _execute_multi_module with enum only to cover non-BaseModel branch."""
     from datamodel_code_generator.dynamic import _execute_multi_module