[dart] Fix enum defaults, Object arrays, and nullable required assertions in native serialization (#23027)

* fix(dart): fix enum defaults, Object arrays, and nullable required assertions in native serialization

* update docs

Author: EddieRydell

docs/generators/dart-dio.md

@@ -58,6 +58,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 ## LANGUAGE PRIMITIVES
 
 <ul class="column-ul">
+<li>Object</li>
 <li>String</li>
 <li>bool</li>
 <li>double</li>

docs/generators/dart.md

@@ -54,6 +54,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 ## LANGUAGE PRIMITIVES
 
 <ul class="column-ul">
+<li>Object</li>
 <li>String</li>
 <li>bool</li>
 <li>double</li>

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

@@ -128,7 +128,8 @@ public AbstractDartCodegen() {
                 "bool",
                 "int",
                 "num",
-                "double"
+                "double",
+                "Object"
         );
 
         typeMapping = new HashMap<>();

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

@@ -119,10 +119,14 @@ class {{{classname}}} {
       // Note 1: the values aren't checked for validity beyond being non-null.
       // Note 2: this code is stripped in release mode!
       assert(() {
-        requiredKeys.forEach((key) {
-          assert(json.containsKey(key), 'Required key "{{{classname}}}[$key]" is missing from JSON.');
-          assert(json[key] != null, 'Required key "{{{classname}}}[$key]" has a null value in JSON.');
-        });
+  {{#vars}}
+    {{#required}}
+        assert(json.containsKey(r'{{{baseName}}}'), 'Required key "{{{classname}}}[{{{baseName}}}]" is missing from JSON.');
+      {{^isNullable}}
+        assert(json[r'{{{baseName}}}'] != null, 'Required key "{{{classname}}}[{{{baseName}}}]" has a null value in JSON.');
+      {{/isNullable}}
+    {{/required}}
+  {{/vars}}
         return true;
       }());
 
@@ -221,7 +225,7 @@ class {{{classname}}} {
         {{{name}}}: mapValueOfType<{{{datatypeWithEnum}}}>(json, r'{{{baseName}}}'){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}},
                 {{/isEnum}}
                 {{#isEnum}}
-        {{{name}}}: {{{enumName}}}.fromJson(json[r'{{{baseName}}}']){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? {{{.}}}{{/defaultValue}}{{/required}},
+        {{{name}}}: {{{enumName}}}.fromJson(json[r'{{{baseName}}}']){{#required}}{{^isNullable}}!{{/isNullable}}{{/required}}{{^required}}{{#defaultValue}} ?? const {{{enumName}}}._({{{.}}}){{/defaultValue}}{{/required}},
                 {{/isEnum}}
               {{/isNumber}}
             {{/isMap}}

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

@@ -17,15 +17,18 @@
 
 package org.openapitools.codegen.dart;
 
-import org.openapitools.codegen.CodegenConstants;
+import org.openapitools.codegen.*;
+import org.openapitools.codegen.config.CodegenConfigurator;
 import org.openapitools.codegen.languages.DartClientCodegen;
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
 import java.io.BufferedReader;
+import java.io.File;
 import java.io.FileInputStream;
 import java.io.InputStreamReader;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
@@ -96,4 +99,74 @@ public void testEnumPropertyWithQuotes() {
         Assert.assertEquals(codegen.toEnumValue("1.0", "number"), "1.0");
         Assert.assertEquals(codegen.toEnumValue("1", "int"), "1");
     }
+
+    private List<File> generateDartNativeFromSpec(String specPath) throws Exception {
+        File output = Files.createTempDirectory("dart-native-test").toFile();
+        output.deleteOnExit();
+
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+                .setGeneratorName("dart")
+                .setInputSpec(specPath)
+                .setOutputDir(output.getAbsolutePath().replace("\\", "/"));
+
+        ClientOptInput opts = configurator.toClientOptInput();
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(opts).generate();
+        files.forEach(File::deleteOnExit);
+        return files;
+    }
+
+    @Test(description = "Object-typed arrays should not produce Object.listFromJson()")
+    public void testObjectArrayDoesNotUseListFromJson() 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("object_array_model.dart"))
+                .findFirst()
+                .orElseThrow(() -> new AssertionError("object_array_model.dart not found in generated files"));
+
+        // Object is a primitive type and has no listFromJson — should use cast<Object>() instead
+        TestUtils.assertFileNotContains(modelFile.toPath(), "Object.listFromJson");
+        TestUtils.assertFileContains(modelFile.toPath(), "cast<Object>");
+    }
+
+    @Test(description = "Enum properties with defaults should emit enum constructor, not string literal")
+    public void testEnumDefaultUsesEnumConstructor() 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("enum_default_model.dart"))
+                .findFirst()
+                .orElseThrow(() -> new AssertionError("enum_default_model.dart not found in generated files"));
+
+        // Default should use const EnumType._('value'), not a bare string literal
+        TestUtils.assertFileNotContains(modelFile.toPath(), "?? 'active'");
+        TestUtils.assertFileContains(modelFile.toPath(),
+                "?? const EnumDefaultModelStatusEnum._('active')");
+    }
+
+    @Test(description = "Required+nullable fields should not assert non-null")
+    public void testRequiredNullableFieldsDoNotAssertNonNull() 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("nullable_required_model.dart"))
+                .findFirst()
+                .orElseThrow(() -> new AssertionError("nullable_required_model.dart not found in generated files"));
+
+        // Required key 'name' (non-nullable) should assert both presence and non-null
+        TestUtils.assertFileContains(modelFile.toPath(),
+                "json.containsKey(r'name')");
+        TestUtils.assertFileContains(modelFile.toPath(),
+                "json[r'name'] != null");
+
+        // Required key 'nickname' (nullable) should assert presence but NOT non-null
+        TestUtils.assertFileContains(modelFile.toPath(),
+                "json.containsKey(r'nickname')");
+        TestUtils.assertFileNotContains(modelFile.toPath(),
+                "json[r'nickname'] != null");
+    }
 }

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

@@ -0,0 +1,34 @@
+openapi: 3.0.0
+info:
+  title: Dart Native Deserialization Bugs
+  description: Test spec for verifying fixes to Dart native serialization codegen bugs.
+  version: 1.0.0
+paths: {}
+components:
+  schemas:
+    ObjectArrayModel:
+      type: object
+      properties:
+        items:
+          type: array
+          items: {}
+    EnumDefaultModel:
+      type: object
+      properties:
+        status:
+          type: string
+          enum:
+            - active
+            - inactive
+          default: active
+    NullableRequiredModel:
+      type: object
+      required:
+        - name
+        - nickname
+      properties:
+        name:
+          type: string
+        nickname:
+          type: string
+          nullable: true

samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/model/api_response.dart

@@ -89,10 +89,6 @@ class ApiResponse {
       // Note 1: the values aren't checked for validity beyond being non-null.
       // Note 2: this code is stripped in release mode!
       assert(() {
-        requiredKeys.forEach((key) {
-          assert(json.containsKey(key), 'Required key "ApiResponse[$key]" is missing from JSON.');
-          assert(json[key] != null, 'Required key "ApiResponse[$key]" has a null value in JSON.');
-        });
         return true;
       }());
 

samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/model/category.dart

@@ -73,10 +73,6 @@ class Category {
       // Note 1: the values aren't checked for validity beyond being non-null.
       // Note 2: this code is stripped in release mode!
       assert(() {
-        requiredKeys.forEach((key) {
-          assert(json.containsKey(key), 'Required key "Category[$key]" is missing from JSON.');
-          assert(json[key] != null, 'Required key "Category[$key]" has a null value in JSON.');
-        });
         return true;
       }());
 

samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/model/order.dart

@@ -122,10 +122,6 @@ class Order {
       // Note 1: the values aren't checked for validity beyond being non-null.
       // Note 2: this code is stripped in release mode!
       assert(() {
-        requiredKeys.forEach((key) {
-          assert(json.containsKey(key), 'Required key "Order[$key]" is missing from JSON.');
-          assert(json[key] != null, 'Required key "Order[$key]" has a null value in JSON.');
-        });
         return true;
       }());
 

samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/model/pet.dart

@@ -102,10 +102,10 @@ class Pet {
       // Note 1: the values aren't checked for validity beyond being non-null.
       // Note 2: this code is stripped in release mode!
       assert(() {
-        requiredKeys.forEach((key) {
-          assert(json.containsKey(key), 'Required key "Pet[$key]" is missing from JSON.');
-          assert(json[key] != null, 'Required key "Pet[$key]" has a null value in JSON.');
-        });
+        assert(json.containsKey(r'name'), 'Required key "Pet[name]" is missing from JSON.');
+        assert(json[r'name'] != null, 'Required key "Pet[name]" has a null value in JSON.');
+        assert(json.containsKey(r'photoUrls'), 'Required key "Pet[photoUrls]" is missing from JSON.');
+        assert(json[r'photoUrls'] != null, 'Required key "Pet[photoUrls]" has a null value in JSON.');
         return true;
       }());