Refactor parent module handling in import logic and add generated __init__.py files (#2662)

Author: koxudaxi

src/datamodel_code_generator/parser/base.py

@@ -2426,9 +2426,15 @@ class Processed(NamedTuple):
             imports = module_to_import[module_] = Imports(self.use_exact_imports)
             init = False
             if module_:
-                parent = (*module_[:-1], "__init__.py")
-                if parent not in results:
-                    results[parent] = Result(body="")
+                if len(module_) == 1:
+                    parent = ("__init__.py",)
+                    if parent not in results:
+                        results[parent] = Result(body="")
+                else:
+                    for i in range(1, len(module_)):
+                        parent = (*module_[:i], "__init__.py")
+                        if parent not in results:
+                            results[parent] = Result(body="")
                 if (*module_, "__init__.py") in results:
                     module = (*module_, "__init__.py")
                     init = True

tests/data/expected/main/jsonschema/nested_directory/definitions/relative/__init__.py

@@ -0,0 +1,3 @@
+# generated by datamodel-codegen:
+#   filename:  external_files_in_directory
+#   timestamp: 2019-07-26T00:00:00+00:00

tests/data/expected/main/jsonschema/use_union_operator/definitions/relative/__init__.py

@@ -0,0 +1,3 @@
+# generated by datamodel-codegen:
+#   filename:  external_files_in_directory
+#   timestamp: 2019-07-26T00:00:00+00:00

tests/data/expected/main/openapi/nested_package_enum_default/io/__init__.py

@@ -0,0 +1,3 @@
+# generated by datamodel-codegen:
+#   filename:  nested_package_enum_default.json
+#   timestamp: 1985-10-26T08:21:00+00:00

tests/data/expected/main/openapi/nested_package_enum_default/io/example/__init__.py

@@ -0,0 +1,3 @@
+# generated by datamodel-codegen:
+#   filename:  nested_package_enum_default.json
+#   timestamp: 1985-10-26T08:21:00+00:00