python 3.8 and pydantic 1 compat

tests/test_forms_defaults.py

@@ -1,29 +1,49 @@
-from typing import Annotated, Optional
+from importlib.metadata import version
+from typing import Optional
 
 import pytest
 from fastapi import FastAPI, Form
-from pydantic import BaseModel, Field, model_validator
+from pydantic import BaseModel, Field
 from starlette.testclient import TestClient
+from typing_extensions import Annotated
+
+PYDANTIC_V2 = int(version("pydantic")[0]) >= 2
+
+if PYDANTIC_V2:
+    from pydantic import model_validator
+else:
+    from pydantic import root_validator
+
+
+def _validate_input(value: dict) -> dict:
+    """
+    model validators in before mode should receive values passed
+    to model instantiation before any further validation
+    """
+    # we should not be double-instantiating the models
+    assert isinstance(value, dict)
+    value["init_input"] = value.copy()
+
+    # differentiate between explicit Nones and unpassed values
+    if "true_if_unset" not in value:
+        value["true_if_unset"] = True
+    return value
 
 
 class Parent(BaseModel):
     init_input: dict
     # importantly, no default here
 
-    @model_validator(mode="before")
-    def validate_inputs(cls, value: dict) -> dict:
-        """
-        model validators in before mode should receive values passed
-        to model instantiation before any further validation
-        """
-        # we should not be double-instantiating the models
-        assert isinstance(value, dict)
-        value["init_input"] = value.copy()
-
-        # differentiate between explicit Nones and unpassed values
-        if "true_if_unset" not in value:
-            value["true_if_unset"] = True
-        return value
+    if PYDANTIC_V2:
+
+        @model_validator(mode="before")
+        def validate_inputs(cls, value: dict) -> dict:
+            return _validate_input(value)
+    else:
+
+        @root_validator(pre=True)
+        def validate_inputs(cls, value: dict) -> dict:
+            return _validate_input(value)
 
 
 class StandardModel(Parent):