Add support for computed property (#286)

Author: zmievsa

CHANGELOG.md

@@ -5,6 +5,12 @@ Please follow [the Keep a Changelog standard](https://keepachangelog.com/en/1.0.
 
 ## [Unreleased]
 
+## [5.4.2]
+
+### Fixed
+
+* Added support for computed fields
+
 ## [5.4.1]
 
 ### Fixed

cadwyn/schema_generation.py

@@ -236,6 +236,11 @@ def _wrap_validator(func: Callable, is_pydantic_v1_style_validator: Any, decorat
         func = func.__func__
     kwargs = dataclasses.asdict(decorator_info)
     decorator_fields = kwargs.pop("fields", None)
+
+    # wrapped_property is not accepted by computed_field()
+    if isinstance(decorator_info, ComputedFieldInfo):
+        kwargs.pop("wrapped_property", None)
+
     actual_decorator = PYDANTIC_DECORATOR_TYPE_TO_DECORATOR_MAP[type(decorator_info)]
     if is_pydantic_v1_style_validator:
         # There's an inconsistency in their interfaces so we gotta resort to this
@@ -1061,19 +1066,30 @@ def _delete_field_attributes(
 
 
 def _delete_field_from_model(model: _PydanticModelWrapper, field_name: str, version_change_name: str):
-    if field_name not in model.fields:
+    if field_name in model.fields:
+        model.fields.pop(field_name)
+        model.annotations.pop(field_name)
+        for validator_name, validator in model.validators.copy().items():
+            if isinstance(validator, _PerFieldValidatorWrapper) and field_name in validator.fields:
+                validator.fields.remove(field_name)
+                # TODO: This behavior doesn't feel natural
+                if not validator.fields:
+                    model.validators[validator_name].is_deleted = True
+
+    elif (
+        field_name in model.validators
+        and isinstance(model.validators[field_name], _ValidatorWrapper)
+        and hasattr(model.validators[field_name], "decorator")
+        and model.validators[field_name].decorator == pydantic.computed_field
+    ):
+        validator = model.validators[field_name]
+        model.validators[field_name].is_deleted = True
+        model.annotations.pop(field_name, None)
+    else:
         raise InvalidGenerationInstructionError(
             f'You tried to delete a field "{field_name}" from "{model.name}" '
             f'in "{version_change_name}" but it doesn\'t have such a field.',
         )
-    model.fields.pop(field_name)
-    model.annotations.pop(field_name)
-    for validator_name, validator in model.validators.copy().items():
-        if isinstance(validator, _PerFieldValidatorWrapper) and field_name in validator.fields:
-            validator.fields.remove(field_name)
-            # TODO: This behavior doesn't feel natural
-            if not validator.fields:
-                model.validators[validator_name].is_deleted = True
 
 
 class _DummyEnum(Enum):

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "cadwyn"
-version = "5.4.1"
+version = "5.4.2"
 description = "Production-ready community-driven modern Stripe-like API versioning in FastAPI"
 authors = [{ name = "Stanislav Zmiev", email = "zmievsa@gmail.com" }]
 license = "MIT"

tests/test_schema_generation/test_schema_field.py

@@ -3,7 +3,7 @@
 from typing import Annotated, Any, Literal, Union
 
 import pytest
-from pydantic import BaseModel, Field, StringConstraints, ValidationError, conint, constr
+from pydantic import BaseModel, Field, StringConstraints, ValidationError, computed_field, conint, constr
 from pydantic.fields import FieldInfo
 
 from cadwyn.exceptions import (
@@ -762,3 +762,48 @@ def test__schema_field_had__nonexistent_field__should_raise_error(create_runtime
         ),
     ):
         create_runtime_schemas(version_change(schema(SchemaWithOneStrField).field("boo").had(type=int)))
+
+
+def test__schema_with_computed_field__should_be_recreated_in_older_version(
+    create_runtime_schemas: CreateRuntimeSchemas,
+):
+    class SchemaWithComputedField(BaseModel):
+        image_file_key: str = Field(exclude=True)
+
+        @computed_field
+        @property
+        def image_url(self) -> str:
+            return f"https://example.com/{self.image_file_key}"
+
+    schemas = create_runtime_schemas(version_change())
+
+    latest_model = schemas["2001-01-01"][SchemaWithComputedField]
+    old_model = schemas["2000-01-01"][SchemaWithComputedField]
+
+    latest_instance = latest_model(image_file_key="test.jpg")
+    old_instance = old_model(image_file_key="test.jpg")
+
+    assert latest_instance.image_url == "https://example.com/test.jpg"
+    assert old_instance.image_url == "https://example.com/test.jpg"
+
+
+def test__schema_with_computed_field__remove_computed_field(create_runtime_schemas: CreateRuntimeSchemas):
+    class SchemaWithComputedField(BaseModel):
+        image_file_key: str = Field(exclude=True)
+
+        @computed_field
+        @property
+        def image_url(self) -> str:
+            return f"https://example.com/{self.image_file_key}"
+
+    schemas = create_runtime_schemas(version_change(schema(SchemaWithComputedField).field("image_url").didnt_exist))
+
+    latest_model = schemas["2001-01-01"][SchemaWithComputedField]
+    latest_instance = latest_model(image_file_key="test.jpg")
+    assert latest_instance.image_url == "https://example.com/test.jpg"
+
+    old_model = schemas["2000-01-01"][SchemaWithComputedField]
+    old_instance = old_model(image_file_key="test.jpg")
+
+    assert not hasattr(old_instance, "image_url")
+    assert "image_url" not in old_instance.model_dump()