From d7fab05c6de35532c2754c6c2d70dcb5e87a67cc Mon Sep 17 00:00:00 2001
From: Chris <chris@komposta.net>
Date: Mon, 14 Jun 2021 22:06:32 +0300
Subject: [PATCH] JSON Parser: try all someclasses for element nodes

---
 tests/fixtures/models.py                     | 20 ++++++++++++++++++++
 tests/formats/dataclass/parsers/test_json.py |  8 ++++++++
 xsdata/formats/dataclass/parsers/json.py     |  7 +++++++
 3 files changed, 35 insertions(+)

diff --git a/tests/fixtures/models.py b/tests/fixtures/models.py
index 6a61fb622..41d020183 100644
--- a/tests/fixtures/models.py
+++ b/tests/fixtures/models.py
@@ -40,6 +40,21 @@ class TypeDuplicate:
     x1: str = field(metadata={"name": "x"})
 
 
+@dataclass
+class BaseA:
+    x: str
+
+
+@dataclass
+class BaseB(BaseA):
+    y: str
+
+
+@dataclass
+class BaseC(BaseB):
+    z: str
+
+
 @dataclass
 class ExtendedType:
     a: Optional[TypeA] = field(default=None)
@@ -75,6 +90,11 @@ class UnionType:
     element: Union[TypeA, TypeB, TypeC, TypeD]
 
 
+@dataclass
+class BaseType:
+    element: BaseA
+
+
 @dataclass
 class AttrsType:
     index: int = field(metadata={"type": "Attribute"})
diff --git a/tests/formats/dataclass/parsers/test_json.py b/tests/formats/dataclass/parsers/test_json.py
index d134d4ecb..bb8ef91fc 100644
--- a/tests/formats/dataclass/parsers/test_json.py
+++ b/tests/formats/dataclass/parsers/test_json.py
@@ -7,6 +7,8 @@
 from tests.fixtures.books import BookForm
 from tests.fixtures.books import Books
 from tests.fixtures.models import AttrsType
+from tests.fixtures.models import BaseC
+from tests.fixtures.models import BaseType
 from tests.fixtures.models import ChoiceType
 from tests.fixtures.models import ExtendedType
 from tests.fixtures.models import TypeA
@@ -223,6 +225,12 @@ def test_bind_dataclass_union(self):
             str(cm.exception),
         )
 
+    def test_bind_dataclass_subclasses(self):
+        data = {"element": {"x": "1", "y": "foo", "z": "1.0"}}
+        actual = self.parser.bind_dataclass(data, BaseType)
+
+        self.assertIsInstance(actual.element, BaseC)
+
     def test_bind_attributes(self):
         data = {"attrs": {"a": 1, "b": 2}, "index": 1}
 
diff --git a/xsdata/formats/dataclass/parsers/json.py b/xsdata/formats/dataclass/parsers/json.py
index 60be71545..a598b1ff2 100644
--- a/xsdata/formats/dataclass/parsers/json.py
+++ b/xsdata/formats/dataclass/parsers/json.py
@@ -258,6 +258,13 @@ def bind_complex_type(self, meta: XmlMeta, var: XmlVar, data: Dict) -> Any:
             return self.bind_best_dataclass(data, meta.element_types)
         else:
             assert var.clazz is not None
+
+            subclasses = set(self.context.get_subclasses(var.clazz))
+            if subclasses:
+                # field annotation is an abstract/base type
+                subclasses.add(var.clazz)
+                return self.bind_best_dataclass(data, subclasses)
+
             return self.bind_dataclass(data, var.clazz)
 
     def bind_derived_value(self, meta: XmlMeta, var: XmlVar, data: Dict) -> T: