use wrap validator to remove failing values

docs_src/query_params/tutorial007_py310.py

@@ -1,4 +1,4 @@
-from typing import Dict, List
+from typing import Annotated, Dict, List, Union
 
 from fastapi import FastAPI, Query
 
@@ -7,14 +7,16 @@ app = FastAPI()
 
 @app.get("/query/mixed-type-params")
 def get_mixed_mapping_mixed_type_query_params(
-    query: int = Query(),
+    query: Annotated[int, Query()] = None,
-    mapping_query_str: Dict[str, str] = Query({}),
+    mapping_query_str_or_int: Annotated[
-    mapping_query_int: Dict[str, int] = Query({}),
+        Union[Dict[str, str], Dict[str, int]], Query()
-    sequence_mapping_queries: Dict[str, List[int]] = Query({}),
+    ] = None,
+    mapping_query_int: Annotated[Dict[str, int], Query()] = None,
+    sequence_mapping_int: Annotated[Dict[str, List[int]], Query()] = None,
 ):
     return {
         "query": query,
-        "string_mapping": mapping_query_str,
+        "mapping_query_str_or_int": mapping_query_str_or_int,
         "mapping_query_int": mapping_query_int,
-        "sequence_mapping_queries": sequence_mapping_queries,
+        "sequence_mapping_int": sequence_mapping_int,
     }

fastapi/_compat/shared.py

@@ -173,7 +173,10 @@ def field_annotation_is_scalar_sequence_mapping(
             if field_annotation_is_scalar_sequence_mapping(arg):
                 at_least_one_scalar_mapping = True
                 continue
-            elif not field_annotation_is_scalar(arg):
+            elif not (
+                field_annotation_is_scalar_sequence_mapping(arg)
+                or field_annotation_is_scalar_mapping(arg)
+            ):
                 return False
         return at_least_one_scalar_mapping
     return lenient_issubclass(origin, Mapping) and all(

fastapi/dependencies/utils.py

@@ -12,7 +12,6 @@ from typing import (
     Mapping,
     Optional,
     Sequence,
-    Set,
     Tuple,
     Type,
     Union,
@@ -64,7 +63,7 @@ from fastapi.security.oauth2 import OAuth2, SecurityScopes
 from fastapi.security.open_id_connect_url import OpenIdConnect
 from fastapi.types import DependencyCacheKey
 from fastapi.utils import create_model_field, get_path_param_names
-from pydantic import BaseModel
+from pydantic import BaseModel, ValidationError, WrapValidator
 from pydantic.fields import FieldInfo
 from starlette.background import BackgroundTasks as StarletteBackgroundTasks
 from starlette.concurrency import run_in_threadpool
@@ -330,6 +329,25 @@ def add_non_field_param_to_dependency(
         return True
     return None
 
+def remove_invalid(v: Any, handler: Callable[[Any], Any]) -> Any:
+    try:
+        return handler(v)
+    except ValidationError as exc:
+        if not isinstance(v, dict):
+            raise exc
+        # remove invalid values from invalid keys and revalidate
+        errors = may_v1._regenerate_error_with_loc(errors=[exc.errors()], loc_prefix=())
+        for err in errors:
+            loc = err.get("loc", ())
+            if len(loc) == 1:
+                v.pop(loc[0], None)
+            elif len(loc) == 2 and isinstance(v.get(loc[0]), list):
+                try:
+                    v[loc[0]].pop(int(loc[1]))
+                except (ValueError, IndexError):
+                    pass
+        return handler(v)
+
 
 @dataclass
 class ParamDetails:
@@ -497,7 +515,16 @@ def analyze_param(
             alias = param_name.replace("_", "-")
         else:
             alias = field_info.alias or param_name
+
         field_info.alias = alias
+
+        if is_scalar_sequence_field(field) or is_scalar_sequence_mapping_field(field):
+            # Wrap the validator to remove invalid values from scalar sequence
+            # and scalar sequence mapping fields instead of failing the whole validation
+            field_info.metadata = getattr(field_info, "metadata", []) + [
+                WrapValidator(remove_invalid)
+            ]
+
         field = create_model_field(
             name=param_name,
             type_=use_annotation_from_field_info,
@@ -702,13 +729,6 @@ async def solve_dependencies(
     )
 
 
-def _extract_error_locs(errors_: Sequence[Any]) -> Set[str]:
-    if isinstance(errors_, list):
-        errors_ = may_v1._regenerate_error_with_loc(errors=errors_, loc_prefix=())
-
-    return {err["loc"][2] for err in errors_ if len(err["loc"]) >= 3}
-
-
 def _validate_value_with_model_field(
     *, field: ModelField, value: Any, values: Dict[str, Any], loc: Tuple[str, ...]
 ) -> Tuple[Any, List[Any]]:
@@ -718,19 +738,6 @@ def _validate_value_with_model_field(
         else:
             return deepcopy(field.default), []
     v_, errors_ = field.validate(value, values, loc=loc)
-    if (
-        errors_
-        and isinstance(field.field_info, params.Query)
-        and isinstance(value, Mapping)
-        and (is_scalar_sequence_mapping_field(field) or is_scalar_mapping_field(field))
-    ):
-        # Remove failing keys from the dict and try to re-validate
-        invalid_keys = _extract_error_locs(errors_)
-        v_, errors_ = field.validate(
-            {k: v for k, v in value.items() if k not in invalid_keys},
-            values,
-            loc=loc,
-        )
 
     if _is_error_wrapper(errors_):  # type: ignore[arg-type]
         return None, [errors_]

tests/test_tutorial/test_query_params/test_tutorial007_py310.py

@@ -15,7 +15,21 @@ def test_foo_needy_very(client: TestClient):
     assert response.status_code == 200
     assert response.json() == {
         "query": 2,
-        "string_mapping": {"foo": "baz"},
+        "mapping_query_str_or_int": {"foo": "baz"},
-        "mapping_query_int": {},
+        "mapping_query_int": None,
-        "sequence_mapping_queries": {},
+        "sequence_mapping_int": None,
     }
+
+
+def test_just_string_not_scalar_mapping(client: TestClient):
+    response = client.get(
+        "/query/mixed-type-params?&query=2&foo=1&bar=3&foo=2&foo=baz"
+    )
+    assert response.status_code == 200
+    assert response.json() == {
+        "query": 2,
+        "mapping_query_str_or_int": {"bar": "3", "foo": "baz"},
+        "mapping_query_int": {"bar": 3},
+        "sequence_mapping_int": {"bar": [3], "foo": [1, 2]},
+    }
+