Fix inconsistent Python union creator function naming

scripts/generate_code.py

@@ -422,6 +422,11 @@ def glob(path, pattern):
     schema="nested_union_test.fbs",
 )
 
+flatc(
+    ["--python", "--gen-object-api"],
+    schema="union_name_test.fbs",
+)
+
 flatc(
     NO_INCL_OPTS + CPP_OPTS,
     schema="default_vectors_strings_test.fbs",

src/idl_gen_python.cpp

@@ -2095,12 +2095,12 @@ class PythonGenerator : public BaseGenerator {
     const auto field_method = namer_.Method(field);
     const auto struct_var = namer_.Variable(struct_def);
     const EnumDef& enum_def = *field.value.type.enum_def;
-    auto union_type = namer_.Type(enum_def);
+    auto union_fn = namer_.Function(enum_def);
 
     if (parser_.opts.include_dependence_headers) {
-      union_type = namer_.NamespacedType(enum_def) + "." + union_type;
+      union_fn = namer_.NamespacedType(enum_def) + "." + union_fn;
     }
-    code += GenIndents(2) + "self." + field_field + " = " + union_type +
+    code += GenIndents(2) + "self." + field_field + " = " + union_fn +
             "Creator(" + "self." + field_field + "Type, " + struct_var + "." +
             field_method + "())";
   }

tests/PythonTest.sh

@@ -28,6 +28,7 @@ ${test_dir}/../flatc -p -o ${gen_code_path} -I include_test monster_extra.fbs --
 ${test_dir}/../flatc -p -o ${gen_code_path} -I include_test arrays_test.fbs --gen-object-api --python-typing
 ${test_dir}/../flatc -p -o ${gen_code_path} -I include_test nested_union_test.fbs --gen-object-api --python-typing --python-decode-obj-api-strings
 ${test_dir}/../flatc -p -o ${gen_code_path} -I include_test service_test.fbs --grpc --grpc-python-typed-handlers --python-typing --no-python-gen-numpy --gen-onefile
+${test_dir}/../flatc -p -o ${gen_code_path} union_name_test.fbs --gen-object-api
 
 # Syntax: run_tests <interpreter> <benchmark vtable dedupes>
 #                   <benchmark read count> <benchmark build count>

tests/py_test.py

@@ -55,6 +55,10 @@
 import monster_test_generated  # the one-file version
 import optional_scalars
 import optional_scalars.ScalarStuff
+import union_name_test.Container  # refers to generated code
+import union_name_test.Foo  # refers to generated code
+import union_name_test.Bar  # refers to generated code
+import union_name_test.my_test_union  # refers to generated code
 
 
 def create_namespace_shortcut(is_onefile):
@@ -3020,6 +3024,50 @@ def test_nested_union_tables(self):
     )
 
 
+class TestUnionCreatorNaming(unittest.TestCase):
+  """Tests that union creator functions use consistent naming (issue #8843).
+
+  Uses a schema with a snake_case union name (my_test_union) to verify that
+  the generated creator function name matches between definition and call site.
+  """
+
+  def test_union_creator_pack_unpack(self):
+    """Pack and UnPack a table with a non-UpperCamel union name."""
+    containerT = union_name_test.Container.ContainerT()
+    containerT.uType = union_name_test.my_test_union.my_test_union.Foo
+    containerT.u = union_name_test.Foo.FooT()
+    containerT.u.val = 42
+
+    b = flatbuffers.Builder(0)
+    b.Finish(containerT.Pack(b))
+
+    container = union_name_test.Container.Container.GetRootAs(
+        b.Bytes, b.Head()
+    )
+    containerT2 = union_name_test.Container.ContainerT.InitFromObj(container)
+
+    self.assertEqual(containerT2.uType, union_name_test.my_test_union.my_test_union.Foo)
+    self.assertEqual(containerT2.u.val, 42)
+
+  def test_union_creator_with_bar(self):
+    """Test the other union variant to ensure all branches work."""
+    containerT = union_name_test.Container.ContainerT()
+    containerT.uType = union_name_test.my_test_union.my_test_union.Bar
+    containerT.u = union_name_test.Bar.BarT()
+    containerT.u.name = "hello"
+
+    b = flatbuffers.Builder(0)
+    b.Finish(containerT.Pack(b))
+
+    container = union_name_test.Container.Container.GetRootAs(
+        b.Bytes, b.Head()
+    )
+    containerT2 = union_name_test.Container.ContainerT.InitFromObj(container)
+
+    self.assertEqual(containerT2.uType, union_name_test.my_test_union.my_test_union.Bar)
+    self.assertEqual(containerT2.u.name, b"hello")
+
+
 class TestBuilderClear(unittest.TestCase):
 
   def test_consistency(self):

tests/union_name_test.fbs

@@ -0,0 +1,21 @@
+// Test for union creator naming consistency (issue #8843).
+// Uses non-UpperCamel union name to verify that Function() naming
+// is used consistently for both definition and call site.
+
+namespace union_name_test;
+
+table Foo {
+  val: int;
+}
+
+table Bar {
+  name: string;
+}
+
+union my_test_union { Foo, Bar }
+
+table Container {
+  u: my_test_union;
+}
+
+root_type Container;

tests/union_name_test/Bar.py

@@ -0,0 +1,93 @@
+# automatically generated by the FlatBuffers compiler, do not modify
+
+# namespace: union_name_test
+
+import flatbuffers
+from flatbuffers.compat import import_numpy
+np = import_numpy()
+
+class Bar(object):
+    __slots__ = ['_tab']
+
+    @classmethod
+    def GetRootAs(cls, buf, offset=0):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, offset)
+        x = Bar()
+        x.Init(buf, n + offset)
+        return x
+
+    @classmethod
+    def GetRootAsBar(cls, buf, offset=0):
+        """This method is deprecated. Please switch to GetRootAs."""
+        return cls.GetRootAs(buf, offset)
+    # Bar
+    def Init(self, buf, pos):
+        self._tab = flatbuffers.table.Table(buf, pos)
+
+    # Bar
+    def Name(self):
+        o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(4))
+        if o != 0:
+            return self._tab.String(o + self._tab.Pos)
+        return None
+
+def BarStart(builder):
+    builder.StartObject(1)
+
+def Start(builder):
+    BarStart(builder)
+
+def BarAddName(builder, name):
+    builder.PrependUOffsetTRelativeSlot(0, flatbuffers.number_types.UOffsetTFlags.py_type(name), 0)
+
+def AddName(builder, name):
+    BarAddName(builder, name)
+
+def BarEnd(builder):
+    return builder.EndObject()
+
+def End(builder):
+    return BarEnd(builder)
+
+
+class BarT(object):
+
+    # BarT
+    def __init__(
+        self,
+        name = None,
+    ):
+        self.name = name  # type: Optional[str]
+
+    @classmethod
+    def InitFromBuf(cls, buf, pos):
+        bar = Bar()
+        bar.Init(buf, pos)
+        return cls.InitFromObj(bar)
+
+    @classmethod
+    def InitFromPackedBuf(cls, buf, pos=0):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, pos)
+        return cls.InitFromBuf(buf, pos+n)
+
+    @classmethod
+    def InitFromObj(cls, bar):
+        x = BarT()
+        x._UnPack(bar)
+        return x
+
+    # BarT
+    def _UnPack(self, bar):
+        if bar is None:
+            return
+        self.name = bar.Name()
+
+    # BarT
+    def Pack(self, builder):
+        if self.name is not None:
+            name = builder.CreateString(self.name)
+        BarStart(builder)
+        if self.name is not None:
+            BarAddName(builder, name)
+        bar = BarEnd(builder)
+        return bar

tests/union_name_test/Container.py

@@ -0,0 +1,120 @@
+# automatically generated by the FlatBuffers compiler, do not modify
+
+# namespace: union_name_test
+
+import flatbuffers
+from flatbuffers.compat import import_numpy
+np = import_numpy()
+
+class Container(object):
+    __slots__ = ['_tab']
+
+    @classmethod
+    def GetRootAs(cls, buf, offset=0):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, offset)
+        x = Container()
+        x.Init(buf, n + offset)
+        return x
+
+    @classmethod
+    def GetRootAsContainer(cls, buf, offset=0):
+        """This method is deprecated. Please switch to GetRootAs."""
+        return cls.GetRootAs(buf, offset)
+    # Container
+    def Init(self, buf, pos):
+        self._tab = flatbuffers.table.Table(buf, pos)
+
+    # Container
+    def UType(self):
+        o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(4))
+        if o != 0:
+            return self._tab.Get(flatbuffers.number_types.Uint8Flags, o + self._tab.Pos)
+        return 0
+
+    # Container
+    def U(self):
+        o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(6))
+        if o != 0:
+            from flatbuffers.table import Table
+            obj = Table(bytearray(), 0)
+            self._tab.Union(obj, o)
+            return obj
+        return None
+
+def ContainerStart(builder):
+    builder.StartObject(2)
+
+def Start(builder):
+    ContainerStart(builder)
+
+def ContainerAddUType(builder, uType):
+    builder.PrependUint8Slot(0, uType, 0)
+
+def AddUType(builder, uType):
+    ContainerAddUType(builder, uType)
+
+def ContainerAddU(builder, u):
+    builder.PrependUOffsetTRelativeSlot(1, flatbuffers.number_types.UOffsetTFlags.py_type(u), 0)
+
+def AddU(builder, u):
+    ContainerAddU(builder, u)
+
+def ContainerEnd(builder):
+    return builder.EndObject()
+
+def End(builder):
+    return ContainerEnd(builder)
+
+import union_name_test.Bar
+import union_name_test.Foo
+import union_name_test.my_test_union
+try:
+    from typing import Union
+except:
+    pass
+
+class ContainerT(object):
+
+    # ContainerT
+    def __init__(
+        self,
+        uType = 0,
+        u = None,
+    ):
+        self.uType = uType  # type: int
+        self.u = u  # type: Union[None, 'union_name_test.Foo.FooT', 'union_name_test.Bar.BarT']
+
+    @classmethod
+    def InitFromBuf(cls, buf, pos):
+        container = Container()
+        container.Init(buf, pos)
+        return cls.InitFromObj(container)
+
+    @classmethod
+    def InitFromPackedBuf(cls, buf, pos=0):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, pos)
+        return cls.InitFromBuf(buf, pos+n)
+
+    @classmethod
+    def InitFromObj(cls, container):
+        x = ContainerT()
+        x._UnPack(container)
+        return x
+
+    # ContainerT
+    def _UnPack(self, container):
+        if container is None:
+            return
+        self.uType = container.UType()
+        self.u = union_name_test.my_test_union.MyTestUnionCreator(self.uType, container.U())
+
+    # ContainerT
+    def Pack(self, builder):
+        if self.u is not None:
+            u = self.u.Pack(builder)
+        ContainerStart(builder)
+        ContainerAddUType(builder, self.uType)
+        if self.u is not None:
+            ContainerAddU(builder, u)
+        container = ContainerEnd(builder)
+        return container