From 22fccb536644c2a82db0ae169ea20c19a64cca13 Mon Sep 17 00:00:00 2001
From: Serge Matveenko <lig@pydantic.dev>
Date: Fri, 23 Jun 2023 12:35:18 +0200
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20Raise=20`PydanticSerializationUn?=
 =?UTF-8?q?expectedValue`=20in=20root=20model=20serializer=20only=20if=20s?=
 =?UTF-8?q?trict=20check=20is=20enabled?=
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---
 src/serializers/type_serializers/model.rs | 10 ++++++---
 tests/serializers/test_model_root.py      | 26 +++++++++++++++++++++++
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/src/serializers/type_serializers/model.rs b/src/serializers/type_serializers/model.rs
index edb7d42ce..bd3777318 100644
--- a/src/serializers/type_serializers/model.rs
+++ b/src/serializers/type_serializers/model.rs
@@ -166,9 +166,13 @@ impl TypeSerializer for ModelSerializer {
         if self.root_model {
             extra.field_name = Some(ROOT_FIELD);
             let py = value.py();
-            let root = value
-                .getattr(intern!(py, ROOT_FIELD))
-                .map_err(|_| PydanticSerializationUnexpectedValue::new_err(None))?;
+            let root = value.getattr(intern!(py, ROOT_FIELD)).map_err(|original_err| {
+                if extra.check.enabled() {
+                    PydanticSerializationUnexpectedValue::new_err(None)
+                } else {
+                    original_err
+                }
+            })?;
             self.serializer.to_python(root, include, exclude, &extra)
         } else if self.allow_value(value, &extra)? {
             let inner_value = self.get_inner_value(value, &extra)?;
diff --git a/tests/serializers/test_model_root.py b/tests/serializers/test_model_root.py
index f4f582994..05600b5b6 100644
--- a/tests/serializers/test_model_root.py
+++ b/tests/serializers/test_model_root.py
@@ -179,3 +179,29 @@ class Model(RootModel):
 
     assert s.to_python(m) == [1, 2, {'value': 'abc'}]
     assert s.to_json(m) == b'[1,2,{"value":"abc"}]'
+
+
+def test_construct_nested():
+    class RModel(RootModel):
+        root: int
+
+    class BModel(BaseModel):
+        value: RModel
+
+    s = SchemaSerializer(
+        core_schema.model_schema(
+            BModel,
+            core_schema.model_fields_schema(
+                {
+                    'value': core_schema.model_field(
+                        core_schema.model_schema(RModel, core_schema.int_schema(), root_model=True)
+                    )
+                }
+            ),
+        )
+    )
+
+    m = BModel(value=42)
+
+    with pytest.raises(AttributeError, match="'int' object has no attribute 'root'"):
+        s.to_python(m)