fix: strictbytes-max-length

changes/4380-JeanArhancet.md

@@ -0,0 +1 @@
+Fix `StrictBytes` does not raise `ValidationError` when `max_length` is present in `Field`

pydantic/schema.py

@@ -57,6 +57,7 @@
     ConstrainedStr,
     SecretBytes,
     SecretStr,
+    StrictBytes,
     conbytes,
     condecimal,
     confloat,
@@ -1087,7 +1088,13 @@ def constraint_func(**kw: Any) -> Type[Any]:
                 constraint_func = constr
             elif issubclass(type_, bytes):
                 attrs = ('max_length', 'min_length', 'regex')
-                constraint_func = conbytes
+                if issubclass(type_, StrictBytes):
+
+                    def constraint_func(**kw: Any) -> Type[Any]:
+                        return type(type_.__name__, (type_,), kw)
+
+                else:
+                    constraint_func = conbytes
             elif issubclass(type_, numeric_types) and not issubclass(
                 type_,
                 (

tests/test_types.py

@@ -1634,6 +1634,18 @@ class Model(BaseModel):
         Model(v=0.42)
 
 
+def test_strict_bytes_max_length():
+    class Model(BaseModel):
+        u: StrictBytes = Field(..., max_length=5)
+
+    assert Model(u=b'foo').u == b'foo'
+
+    with pytest.raises(ValidationError, match='byte type expected'):
+        Model(u=123)
+    with pytest.raises(ValidationError, match='ensure this value has at most 5 characters'):
+        Model(u=b'1234567')
+
+
 def test_strict_bytes_subclass():
     class MyStrictBytes(StrictBytes):
         pass