From fa65a07a0c17b8a13e434202b03d33ef3ab1fd01 Mon Sep 17 00:00:00 2001
From: Denis Kataev <bteamko@gmail.com>
Date: Thu, 28 Mar 2019 20:26:06 +0500
Subject: [PATCH] Correct path in nested models (#437)

* Correct path in nested models

* History

* Fix code review
---
 HISTORY.rst                  |  1 +
 pydantic/error_wrappers.py   |  6 +++++-
 tests/test_error_wrappers.py | 18 ++++++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/HISTORY.rst b/HISTORY.rst
index 03c5954..f76d53f 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -8,6 +8,7 @@ v0.21.1 (unreleased)
 * add ``IPv{4,6,Any}Network`` and ``IPv{4,6,Any}Interface`` types from ``ipaddress`` stdlib, #333 by @pilosus
 * add docs for ``datetime`` types, #386 by @pilosus
 * fix to schema generation in dataclass-based models, #408 by @pilosus
+* fix path in nested models #437, by @kataev
 
 
 v0.21.0 (2019-03-15)
diff --git a/pydantic/error_wrappers.py b/pydantic/error_wrappers.py
index a1ae583..c30db5e 100644
--- a/pydantic/error_wrappers.py
+++ b/pydantic/error_wrappers.py
@@ -93,7 +93,11 @@ def flatten_errors(
     for error in errors:
         if isinstance(error, ErrorWrapper):
             if isinstance(error.exc, ValidationError):
-                yield from flatten_errors(error.exc.raw_errors, loc=error.loc)
+                if loc is not None:
+                    error_loc = loc + error.loc
+                else:
+                    error_loc = error.loc
+                yield from flatten_errors(error.exc.raw_errors, loc=error_loc)
             else:
                 yield error.dict(loc_prefix=loc)
         elif isinstance(error, list):
diff --git a/tests/test_error_wrappers.py b/tests/test_error_wrappers.py
index e299a0b..f019cf4 100644
--- a/tests/test_error_wrappers.py
+++ b/tests/test_error_wrappers.py
@@ -243,3 +243,21 @@ x
 x
   field required (type=value_error.missing)"""
     )
+
+
+def test_nested_error():
+    class NestedModel3(BaseModel):
+        x: str
+
+    class NestedModel2(BaseModel):
+        data2: List[NestedModel3]
+
+    class NestedModel1(BaseModel):
+        data1: List[NestedModel2]
+
+    with pytest.raises(ValidationError) as exc_info:
+        NestedModel1(data1=[{'data2': [{'y': 1}]}])
+
+    expected = [{'loc': ('data1', 0, 'data2', 0, 'x'), 'msg': 'field required', 'type': 'value_error.missing'}]
+
+    assert exc_info.value.errors() == expected