[dart] fix nullable nested array item handling in type declarations and native deserialization

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractDartCodegen.java

@@ -554,13 +554,17 @@ public String toDefaultValue(Schema schema) {
 
     @Override
     public String getTypeDeclaration(Schema p) {
+        return getTypeDeclaration(p, false);
+    }
+
+    private String getTypeDeclaration(Schema p, boolean includeNullableSuffix) {
         Schema<?> schema = unaliasSchema(p);
         Schema<?> target = ModelUtils.isGenerateAliasAsModel() ? p : schema;
+        String typeDeclaration;
         if (ModelUtils.isArraySchema(target)) {
             Schema<?> items = ModelUtils.getSchemaItems(schema);
-            return getSchemaType(target) + "<" + getTypeDeclaration(items) + ">";
-        }
-        if (ModelUtils.isMapSchema(target)) {
+            typeDeclaration = getSchemaType(target) + "<" + getTypeDeclaration(items, true) + ">";
+        } else if (ModelUtils.isMapSchema(target)) {
             // Note: ModelUtils.isMapSchema(p) returns true when p is a composed schema that also defines
             // additionalproperties: true
             Schema<?> inner = ModelUtils.getAdditionalProperties(target);
@@ -569,9 +573,16 @@ public String getTypeDeclaration(Schema p) {
                 inner = new StringSchema().description("TODO default missing map inner type to string");
                 p.setAdditionalProperties(inner);
             }
-            return getSchemaType(target) + "<String, " + getTypeDeclaration(inner) + ">";
+            typeDeclaration = getSchemaType(target) + "<String, " + getTypeDeclaration(inner, true) + ">";
+        } else {
+            typeDeclaration = super.getTypeDeclaration(p);
         }
-        return super.getTypeDeclaration(p);
+
+        if (includeNullableSuffix && ModelUtils.isNullable(schema)) {
+            return typeDeclaration + "?";
+        }
+
+        return typeDeclaration;
     }
 
     @Override

modules/openapi-generator/src/main/resources/dart2/serialization/native/native_class.mustache

@@ -198,10 +198,10 @@ class {{{classname}}} {
         {{{name}}}: json[r'{{{baseName}}}'] is List
           ? (json[r'{{{baseName}}}'] as List).map((e) =>
               {{#items.complexType}}
-              {{items.complexType}}.listFromJson(json[r'{{{baseName}}}']){{#uniqueItems}}.toSet(){{/uniqueItems}}
+              e == null ? {{#items.isNullable}}null{{/items.isNullable}}{{^items.isNullable}}const <{{items.complexType}}>[]{{/items.isNullable}} : {{items.complexType}}.listFromJson(e){{#uniqueItems}}.toSet(){{/uniqueItems}}
               {{/items.complexType}}
               {{^items.complexType}}
-              e == null ? {{#items.isNullable}}null{{/items.isNullable}}{{^items.isNullable}}const  <{{items.items.dataType}}>[]{{/items.isNullable}} : (e as List).cast<{{items.items.dataType}}>()
+              e == null ? {{#items.isNullable}}null{{/items.isNullable}}{{^items.isNullable}}const <{{items.items.dataType}}{{#items.items.isNullable}}?{{/items.items.isNullable}}>[]{{/items.isNullable}} : (e as List).map((value) => value as {{items.items.dataType}}{{#items.items.isNullable}}?{{/items.items.isNullable}}).toList(growable: false)
               {{/items.complexType}}
             ).toList()
           :  {{#isNullable}}null{{/isNullable}}{{^isNullable}}const []{{/isNullable}},
@@ -219,7 +219,7 @@ class {{{classname}}} {
             : {{items.complexType}}.mapListFromJson(json[r'{{{baseName}}}']),
                 {{/items.complexType}}
                 {{^items.complexType}}
-            : (json[r'{{{baseName}}}'] as Map<String, dynamic>).map((k, v) => MapEntry(k, v == null ? {{#items.isNullable}}null{{/items.isNullable}}{{^items.isNullable}}const <{{items.items.dataType}}>[]{{/items.isNullable}} : (v as List).cast<{{items.items.dataType}}>())),
+            : (json[r'{{{baseName}}}'] as Map<String, dynamic>).map((k, v) => MapEntry(k, v == null ? {{#items.isNullable}}null{{/items.isNullable}}{{^items.isNullable}}const <{{items.items.dataType}}{{#items.items.isNullable}}?{{/items.items.isNullable}}>[]{{/items.isNullable}} : (v as List).map((value) => value as {{items.items.dataType}}{{#items.items.isNullable}}?{{/items.items.isNullable}}).toList(growable: false))),
                 {{/items.complexType}}
               {{/items.isArray}}
               {{^items.isArray}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/DartClientCodegenTest.java

@@ -169,4 +169,18 @@ public void testRequiredNullableFieldsDoNotAssertNonNull() throws Exception {
         TestUtils.assertFileNotContains(modelFile.toPath(),
                 "json[r'nickname'] != null");
     }
+
+    @Test(description = "Nullable nested arrays of complex types should preserve null entries")
+    public void testNullableNestedComplexArraysPreserveNullEntries() throws Exception {
+        List<File> files = generateDartNativeFromSpec(
+                "src/test/resources/3_0/dart/dart-native-deserialization-bugs.yaml");
+
+        File modelFile = files.stream()
+                .filter(f -> f.getName().equals("complex_nested_array_nullable_model.dart"))
+                .findFirst()
+                .orElseThrow(() -> new AssertionError("complex_nested_array_nullable_model.dart not found in generated files"));
+
+        TestUtils.assertFileContains(modelFile.toPath(),
+                "e == null ? null : NullableRequiredModel.listFromJson(e)");
+    }
 }

modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/DartModelTest.java

@@ -716,4 +716,28 @@ public void testParameterUnwrappingBehavior() {
         Assert.assertFalse(filterParam.dataType.startsWith("Optional<"),
                 "Query parameter should not be wrapped with Optional");
     }
+
+    @Test(description = "array items can be nullable")
+    public void arrayItemsCanBeNullable() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/array-nullable-items.yaml");
+        final DefaultCodegen codegen = new DartClientCodegen();
+        codegen.setOpenAPI(openAPI);
+        final ArraySchema schema = (ArraySchema) openAPI.getComponents().getSchemas().get("ArrayWithNullableItemsModel")
+                .getProperties()
+                .get("foo");
+
+        Assert.assertEquals(codegen.getTypeDeclaration(schema), "List<String?>");
+    }
+
+    @Test(description = "nested array items can be nullable")
+    public void nestedArrayItemsCanBeNullable() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/nested-array-nullable-items.yaml");
+        final DefaultCodegen codegen = new DartClientCodegen();
+        codegen.setOpenAPI(openAPI);
+        final ArraySchema schema = (ArraySchema) openAPI.getComponents().getSchemas().get("NestedArrayWithNullableItemsModel")
+                .getProperties()
+                .get("foo");
+
+        Assert.assertEquals(codegen.getTypeDeclaration(schema), "List<List<String?>>");
+    }
 }

modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioModelTest.java

@@ -492,4 +492,32 @@ public void dateDefaultValues() {
         Assert.assertEquals(dateTimeDefault.name, "dateTime");
         Assert.assertNull(dateTimeDefault.defaultValue);
     }
+
+    @Test(description = "array items can be nullable")
+    public void arrayItemsCanBeNullable() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/array-nullable-items.yaml");
+        final DartDioClientCodegen codegen = new DartDioClientCodegen();
+        codegen.additionalProperties().put(CodegenConstants.SERIALIZATION_LIBRARY, DartDioClientCodegen.SERIALIZATION_LIBRARY_BUILT_VALUE);
+        codegen.processOpts();
+        codegen.setOpenAPI(openAPI);
+        final ArraySchema schema = (ArraySchema) openAPI.getComponents().getSchemas().get("ArrayWithNullableItemsModel")
+                .getProperties()
+                .get("foo");
+
+        Assert.assertEquals(codegen.getTypeDeclaration(schema), "BuiltList<String?>");
+    }
+
+    @Test(description = "nested array items can be nullable")
+    public void nestedArrayItemsCanBeNullable() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/nested-array-nullable-items.yaml");
+        final DartDioClientCodegen codegen = new DartDioClientCodegen();
+        codegen.additionalProperties().put(CodegenConstants.SERIALIZATION_LIBRARY, DartDioClientCodegen.SERIALIZATION_LIBRARY_BUILT_VALUE);
+        codegen.processOpts();
+        codegen.setOpenAPI(openAPI);
+        final ArraySchema schema = (ArraySchema) openAPI.getComponents().getSchemas().get("NestedArrayWithNullableItemsModel")
+                .getProperties()
+                .get("foo");
+
+        Assert.assertEquals(codegen.getTypeDeclaration(schema), "BuiltList<BuiltList<String?>>");
+    }
 }

modules/openapi-generator/src/test/resources/3_0/dart/dart-native-deserialization-bugs.yaml

@@ -32,3 +32,13 @@ components:
         nickname:
           type: string
           nullable: true
+    ComplexNestedArrayNullableModel:
+      type: object
+      properties:
+        matrix:
+          type: array
+          items:
+            type: array
+            nullable: true
+            items:
+              $ref: '#/components/schemas/NullableRequiredModel'

modules/openapi-generator/src/test/resources/3_0/nested-array-nullable-items.yaml

@@ -0,0 +1,28 @@
+openapi: 3.0.0
+info:
+  title: Nested array nullable items
+  version: latest
+paths:
+  '/':
+    get:
+      operationId: operation
+      responses:
+        '200':
+          description: Success
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/NestedArrayWithNullableItemsModel'
+components:
+  schemas:
+    NestedArrayWithNullableItemsModel:
+      required:
+        - foo
+      properties:
+        foo:
+          type: array
+          items:
+            type: array
+            items:
+              type: string
+              nullable: true

samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/doc/NullableClass.md

@@ -15,11 +15,11 @@ Name | Type | Description | Notes
 **dateProp** | [**DateTime**](DateTime.md) |  | [optional] 
 **datetimeProp** | [**DateTime**](DateTime.md) |  | [optional] 
 **arrayNullableProp** | **List<Object>** |  | [optional] 
-**arrayAndItemsNullableProp** | **List<Object>** |  | [optional] 
-**arrayItemsNullable** | **List<Object>** |  | [optional] 
+**arrayAndItemsNullableProp** | **List<Object?>** |  | [optional] 
+**arrayItemsNullable** | **List<Object?>** |  | [optional] 
 **objectNullableProp** | **Map<String, Object>** |  | [optional] 
-**objectAndItemsNullableProp** | **Map<String, Object>** |  | [optional] 
-**objectItemsNullable** | **Map<String, Object>** |  | [optional] 
+**objectAndItemsNullableProp** | **Map<String, Object?>** |  | [optional] 
+**objectItemsNullable** | **Map<String, Object?>** |  | [optional] 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 

samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/nullable_class.dart

@@ -137,7 +137,7 @@ class NullableClass {
   )
 
 
-  final List<Object>? arrayAndItemsNullableProp;
+  final List<Object?>? arrayAndItemsNullableProp;
 
 
 
@@ -149,7 +149,7 @@ class NullableClass {
   )
 
 
-  final List<Object>? arrayItemsNullable;
+  final List<Object?>? arrayItemsNullable;
 
 
 
@@ -173,7 +173,7 @@ class NullableClass {
   )
 
 
-  final Map<String, Object>? objectAndItemsNullableProp;
+  final Map<String, Object?>? objectAndItemsNullableProp;
 
 
 
@@ -185,7 +185,7 @@ class NullableClass {
   )
 
 
-  final Map<String, Object>? objectItemsNullable;
+  final Map<String, Object?>? objectItemsNullable;
 
 
 

samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/NullableClass.md

@@ -15,11 +15,11 @@ Name | Type | Description | Notes
 **dateProp** | [**Date**](Date.md) |  | [optional] 
 **datetimeProp** | [**DateTime**](DateTime.md) |  | [optional] 
 **arrayNullableProp** | [**BuiltList<JsonObject>**](JsonObject.md) |  | [optional] 
-**arrayAndItemsNullableProp** | [**BuiltList<JsonObject>**](JsonObject.md) |  | [optional] 
-**arrayItemsNullable** | [**BuiltList<JsonObject>**](JsonObject.md) |  | [optional] 
+**arrayAndItemsNullableProp** | [**BuiltList<JsonObject?>**](JsonObject.md) |  | [optional] 
+**arrayItemsNullable** | [**BuiltList<JsonObject?>**](JsonObject.md) |  | [optional] 
 **objectNullableProp** | [**BuiltMap<String, JsonObject>**](JsonObject.md) |  | [optional] 
-**objectAndItemsNullableProp** | [**BuiltMap<String, JsonObject>**](JsonObject.md) |  | [optional] 
-**objectItemsNullable** | [**BuiltMap<String, JsonObject>**](JsonObject.md) |  | [optional] 
+**objectAndItemsNullableProp** | [**BuiltMap<String, JsonObject?>**](JsonObject.md) |  | [optional] 
+**objectItemsNullable** | [**BuiltMap<String, JsonObject?>**](JsonObject.md) |  | [optional] 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 

samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/doc/NullableClass.md

@@ -15,11 +15,11 @@ Name | Type | Description | Notes
 **dateProp** | [**DateTime**](DateTime.md) |  | [optional] 
 **datetimeProp** | [**DateTime**](DateTime.md) |  | [optional] 
 **arrayNullableProp** | **List<Object>** |  | [optional] [default to const []]
-**arrayAndItemsNullableProp** | **List<Object>** |  | [optional] [default to const []]
-**arrayItemsNullable** | **List<Object>** |  | [optional] [default to const []]
+**arrayAndItemsNullableProp** | **List<Object?>** |  | [optional] [default to const []]
+**arrayItemsNullable** | **List<Object?>** |  | [optional] [default to const []]
 **objectNullableProp** | **Map<String, Object>** |  | [optional] [default to const {}]
-**objectAndItemsNullableProp** | **Map<String, Object>** |  | [optional] [default to const {}]
-**objectItemsNullable** | **Map<String, Object>** |  | [optional] [default to const {}]
+**objectAndItemsNullableProp** | **Map<String, Object?>** |  | [optional] [default to const {}]
+**objectItemsNullable** | **Map<String, Object?>** |  | [optional] [default to const {}]
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 

samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/model/additional_properties_class.dart

@@ -67,7 +67,7 @@ class AdditionalPropertiesClass {
         mapOfMapProperty: mapCastOfType<String, dynamic>(json, r'map_of_map_property') ?? const {},
         mapOfArrayInteger: json[r'map_of_array_integer'] == null
           ? const {}
-            : (json[r'map_of_array_integer'] as Map<String, dynamic>).map((k, v) => MapEntry(k, v == null ? const <int>[] : (v as List).cast<int>())),
+            : (json[r'map_of_array_integer'] as Map<String, dynamic>).map((k, v) => MapEntry(k, v == null ? const <int>[] : (v as List).map((value) => value as int).toList(growable: false))),
       );
     }
     return null;

samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/model/array_of_array_of_number_only.dart

@@ -53,7 +53,7 @@ class ArrayOfArrayOfNumberOnly {
       return ArrayOfArrayOfNumberOnly(
         arrayArrayNumber: json[r'ArrayArrayNumber'] is List
           ? (json[r'ArrayArrayNumber'] as List).map((e) =>
-              e == null ? const  <num>[] : (e as List).cast<num>()
+              e == null ? const <num>[] : (e as List).map((value) => value as num).toList(growable: false)
             ).toList()
           :  const [],
       );

samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/model/array_test.dart

@@ -68,12 +68,12 @@ class ArrayTest {
             : const [],
         arrayArrayOfInteger: json[r'array_array_of_integer'] is List
           ? (json[r'array_array_of_integer'] as List).map((e) =>
-              e == null ? const  <int>[] : (e as List).cast<int>()
+              e == null ? const <int>[] : (e as List).map((value) => value as int).toList(growable: false)
             ).toList()
           :  const [],
         arrayArrayOfModel: json[r'array_array_of_model'] is List
           ? (json[r'array_array_of_model'] as List).map((e) =>
-              ReadOnlyFirst.listFromJson(json[r'array_array_of_model'])
+              e == null ? const <ReadOnlyFirst>[] : ReadOnlyFirst.listFromJson(e)
             ).toList()
           :  const [],
       );

samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/model/nullable_class.dart

@@ -41,15 +41,15 @@ class NullableClass {
 
   List<Object>? arrayNullableProp;
 
-  List<Object>? arrayAndItemsNullableProp;
+  List<Object?>? arrayAndItemsNullableProp;
 
-  List<Object> arrayItemsNullable;
+  List<Object?> arrayItemsNullable;
 
   Map<String, Object>? objectNullableProp;
 
-  Map<String, Object>? objectAndItemsNullableProp;
+  Map<String, Object?>? objectAndItemsNullableProp;
 
-  Map<String, Object> objectItemsNullable;
+  Map<String, Object?> objectItemsNullable;
 
   @override
   bool operator ==(Object other) => identical(this, other) || other is NullableClass &&