From b9595fa22862e9af3420c8e814ff20508f98ae04 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebasti=C3=A1n=20Ram=C3=ADrez?= <tiangolo@gmail.com>
Date: Fri, 6 Feb 2026 19:23:14 +0100
Subject: [PATCH] =?UTF-8?q?=F0=9F=94=A5=20Remove=20logic=20no=20longer=20n?=
 =?UTF-8?q?ecessary=20without=20having=20to=20support=20Pydantic=20v1?=
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---
 fastapi/_compat/v2.py | 96 ++++---------------------------------------
 1 file changed, 7 insertions(+), 89 deletions(-)

diff --git a/fastapi/_compat/v2.py b/fastapi/_compat/v2.py
index 1b98b74e58..766976a974 100644
--- a/fastapi/_compat/v2.py
+++ b/fastapi/_compat/v2.py
@@ -1,7 +1,7 @@
 import re
 import warnings
 from collections.abc import Sequence
-from copy import copy, deepcopy
+from copy import copy
 from dataclasses import dataclass, is_dataclass
 from enum import Enum
 from functools import lru_cache
@@ -305,94 +305,12 @@ def get_definitions(
         if "description" in item_def:
             item_description = cast(str, item_def["description"]).split("\f")[0]
             item_def["description"] = item_description
-    new_mapping, new_definitions = _remap_definitions_and_field_mappings(
-        model_name_map=model_name_map,
-        definitions=definitions,  # type: ignore[arg-type]
-        field_mapping=field_mapping,
-    )
-    return new_mapping, new_definitions
-
-
-def _replace_refs(
-    *,
-    schema: dict[str, Any],
-    old_name_to_new_name_map: dict[str, str],
-) -> dict[str, Any]:
-    new_schema = deepcopy(schema)
-    for key, value in new_schema.items():
-        if key == "$ref":
-            value = schema["$ref"]
-            if isinstance(value, str):
-                ref_name = schema["$ref"].split("/")[-1]
-                if ref_name in old_name_to_new_name_map:
-                    new_name = old_name_to_new_name_map[ref_name]
-                    new_schema["$ref"] = REF_TEMPLATE.format(model=new_name)
-            continue
-        if isinstance(value, dict):
-            new_schema[key] = _replace_refs(
-                schema=value,
-                old_name_to_new_name_map=old_name_to_new_name_map,
-            )
-        elif isinstance(value, list):
-            new_value = []
-            for item in value:
-                if isinstance(item, dict):
-                    new_item = _replace_refs(
-                        schema=item,
-                        old_name_to_new_name_map=old_name_to_new_name_map,
-                    )
-                    new_value.append(new_item)
-
-                else:
-                    new_value.append(item)
-            new_schema[key] = new_value
-    return new_schema
-
-
-def _remap_definitions_and_field_mappings(
-    *,
-    model_name_map: ModelNameMap,
-    definitions: dict[str, Any],
-    field_mapping: dict[
-        tuple[ModelField, Literal["validation", "serialization"]], JsonSchemaValue
-    ],
-) -> tuple[
-    dict[tuple[ModelField, Literal["validation", "serialization"]], JsonSchemaValue],
-    dict[str, Any],
-]:
-    old_name_to_new_name_map = {}
-    for field_key, schema in field_mapping.items():
-        model = field_key[0].type_
-        if model not in model_name_map or "$ref" not in schema:
-            continue
-        new_name = model_name_map[model]
-        old_name = schema["$ref"].split("/")[-1]
-        if old_name in {f"{new_name}-Input", f"{new_name}-Output"}:
-            continue
-        old_name_to_new_name_map[old_name] = new_name
-
-    new_field_mapping: dict[
-        tuple[ModelField, Literal["validation", "serialization"]], JsonSchemaValue
-    ] = {}
-    for field_key, schema in field_mapping.items():
-        new_schema = _replace_refs(
-            schema=schema,
-            old_name_to_new_name_map=old_name_to_new_name_map,
-        )
-        new_field_mapping[field_key] = new_schema
-
-    new_definitions = {}
-    for key, value in definitions.items():
-        if key in old_name_to_new_name_map:
-            new_key = old_name_to_new_name_map[key]
-        else:
-            new_key = key
-        new_value = _replace_refs(
-            schema=value,
-            old_name_to_new_name_map=old_name_to_new_name_map,
-        )
-        new_definitions[new_key] = new_value
-    return new_field_mapping, new_definitions
+    # definitions: dict[DefsRef, dict[str, Any]]
+    # but mypy complains about general str in other places that are not declared as
+    # DefsRef, although DefsRef is just str:
+    # DefsRef = NewType('DefsRef', str)
+    # So, a cast to simplify the types here
+    return field_mapping, cast(dict[str, dict[str, Any]], definitions)
 
 
 def is_scalar_field(field: ModelField) -> bool: