diff --git a/modules/openapi-generator/src/main/resources/dart-dio/api.mustache b/modules/openapi-generator/src/main/resources/dart-dio/api.mustache
index a7f830a51352..82b6057a683e 100644
--- a/modules/openapi-generator/src/main/resources/dart-dio/api.mustache
+++ b/modules/openapi-generator/src/main/resources/dart-dio/api.mustache
@@ -76,13 +76,19 @@ class {{classname}} {
         {{/hasFormParams}}
         {{#bodyParam}}
 
-            {{#isArray}}
+        {{#isArray}}
         const type = FullType(BuiltList, [FullType({{baseType}})]);
         final serializedBody = _serializers.serialize({{paramName}}, specifiedType: type);
-            {{/isArray}}
-            {{^isArray}}
-        final serializedBody = _serializers.serialize({{paramName}});
-            {{/isArray}}
+        {{/isArray}}
+        {{^isArray}}
+        {{#isPrimitiveType}}
+        var serializedBody = {{paramName}};
+        {{/isPrimitiveType}}
+        {{^isPrimitiveType}}
+        final bodySerializer = _serializers.serializerForType({{baseType}});
+        final serializedBody = _serializers.serializeWith(bodySerializer, {{paramName}});
+        {{/isPrimitiveType}}
+        {{/isArray}}
         final json{{paramName}} = json.encode(serializedBody);
         bodyData = json{{paramName}};
         {{/bodyParam}}
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
index c975d10e631f..4e37f1e056a1 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
@@ -43,7 +43,8 @@ class PetApi {
             'application/xml',
         ];
 
-        final serializedBody = _serializers.serialize(body);
+        final bodySerializer = _serializers.serializerForType(Pet);
+        final serializedBody = _serializers.serializeWith(bodySerializer, body);
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
@@ -347,7 +348,8 @@ class PetApi {
             'application/xml',
         ];
 
-        final serializedBody = _serializers.serialize(body);
+        final bodySerializer = _serializers.serializerForType(Pet);
+        final serializedBody = _serializers.serializeWith(bodySerializer, body);
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
index eb62c2dc17f5..260956e42153 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
@@ -205,7 +205,8 @@ class StoreApi {
 
         final List<String> contentTypes = [];
 
-        final serializedBody = _serializers.serialize(body);
+        final bodySerializer = _serializers.serializerForType(Order);
+        final serializedBody = _serializers.serializeWith(bodySerializer, body);
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
index 9183e1f5a76a..64d597726099 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
@@ -37,7 +37,8 @@ class UserApi {
 
         final List<String> contentTypes = [];
 
-        final serializedBody = _serializers.serialize(body);
+        final bodySerializer = _serializers.serializerForType(User);
+        final serializedBody = _serializers.serializeWith(bodySerializer, body);
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
@@ -394,7 +395,8 @@ class UserApi {
 
         final List<String> contentTypes = [];
 
-        final serializedBody = _serializers.serialize(body);
+        final bodySerializer = _serializers.serializerForType(User);
+        final serializedBody = _serializers.serializeWith(bodySerializer, body);
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
index 29837e6354be..646a68b206ec 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
@@ -43,7 +43,8 @@ class PetApi {
             'application/xml',
         ];
 
-        final serializedBody = _serializers.serialize(pet);
+        final bodySerializer = _serializers.serializerForType(Pet);
+        final serializedBody = _serializers.serializeWith(bodySerializer, pet);
         final jsonpet = json.encode(serializedBody);
         bodyData = jsonpet;
 
@@ -360,7 +361,8 @@ class PetApi {
             'application/xml',
         ];
 
-        final serializedBody = _serializers.serialize(pet);
+        final bodySerializer = _serializers.serializerForType(Pet);
+        final serializedBody = _serializers.serializeWith(bodySerializer, pet);
         final jsonpet = json.encode(serializedBody);
         bodyData = jsonpet;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
index cc30e5b55972..e7f61eb64090 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
@@ -207,7 +207,8 @@ class StoreApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(order);
+        final bodySerializer = _serializers.serializerForType(Order);
+        final serializedBody = _serializers.serializeWith(bodySerializer, order);
         final jsonorder = json.encode(serializedBody);
         bodyData = jsonorder;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
index c7ba72a9a88a..b3291c98cda8 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
@@ -39,7 +39,8 @@ class UserApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(user);
+        final bodySerializer = _serializers.serializerForType(User);
+        final serializedBody = _serializers.serializeWith(bodySerializer, user);
         final jsonuser = json.encode(serializedBody);
         bodyData = jsonuser;
 
@@ -437,7 +438,8 @@ class UserApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(user);
+        final bodySerializer = _serializers.serializerForType(User);
+        final serializedBody = _serializers.serializeWith(bodySerializer, user);
         final jsonuser = json.encode(serializedBody);
         bodyData = jsonuser;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart
index bb7458c32f1e..b0a1bb7491b8 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart
@@ -38,7 +38,8 @@ class AnotherFakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(modelClient);
+        final bodySerializer = _serializers.serializerForType(ModelClient);
+        final serializedBody = _serializers.serializeWith(bodySerializer, modelClient);
         final jsonmodelClient = json.encode(serializedBody);
         bodyData = jsonmodelClient;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart
index 4347da0f2542..4e054b7de8a1 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart
@@ -108,7 +108,8 @@ class FakeApi {
             'application/xml',
         ];
 
-        final serializedBody = _serializers.serialize(pet);
+        final bodySerializer = _serializers.serializerForType(Pet);
+        final serializedBody = _serializers.serializeWith(bodySerializer, pet);
         final jsonpet = json.encode(serializedBody);
         bodyData = jsonpet;
 
@@ -164,7 +165,7 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(body);
+        var serializedBody = body;
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
@@ -227,7 +228,8 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(outerComposite);
+        final bodySerializer = _serializers.serializerForType(OuterComposite);
+        final serializedBody = _serializers.serializeWith(bodySerializer, outerComposite);
         final jsonouterComposite = json.encode(serializedBody);
         bodyData = jsonouterComposite;
 
@@ -291,7 +293,7 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(body);
+        var serializedBody = body;
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
@@ -354,7 +356,7 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(body);
+        var serializedBody = body;
         final jsonbody = json.encode(serializedBody);
         bodyData = jsonbody;
 
@@ -417,7 +419,8 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(fileSchemaTestClass);
+        final bodySerializer = _serializers.serializerForType(FileSchemaTestClass);
+        final serializedBody = _serializers.serializeWith(bodySerializer, fileSchemaTestClass);
         final jsonfileSchemaTestClass = json.encode(serializedBody);
         bodyData = jsonfileSchemaTestClass;
 
@@ -470,7 +473,8 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(user);
+        final bodySerializer = _serializers.serializerForType(User);
+        final serializedBody = _serializers.serializeWith(bodySerializer, user);
         final jsonuser = json.encode(serializedBody);
         bodyData = jsonuser;
 
@@ -521,7 +525,8 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(modelClient);
+        final bodySerializer = _serializers.serializerForType(ModelClient);
+        final serializedBody = _serializers.serializeWith(bodySerializer, modelClient);
         final jsonmodelClient = json.encode(serializedBody);
         bodyData = jsonmodelClient;
 
@@ -793,7 +798,8 @@ class FakeApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(requestBody);
+        final bodySerializer = _serializers.serializerForType(String);
+        final serializedBody = _serializers.serializeWith(bodySerializer, requestBody);
         final jsonrequestBody = json.encode(serializedBody);
         bodyData = jsonrequestBody;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart
index 568b5043f6d9..ce622874e326 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart
@@ -38,7 +38,8 @@ class FakeClassnameTags123Api {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(modelClient);
+        final bodySerializer = _serializers.serializerForType(ModelClient);
+        final serializedBody = _serializers.serializeWith(bodySerializer, modelClient);
         final jsonmodelClient = json.encode(serializedBody);
         bodyData = jsonmodelClient;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart
index 7f79f93ca0af..e340d126ccf6 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart
@@ -43,7 +43,8 @@ class PetApi {
             'application/xml',
         ];
 
-        final serializedBody = _serializers.serialize(pet);
+        final bodySerializer = _serializers.serializerForType(Pet);
+        final serializedBody = _serializers.serializeWith(bodySerializer, pet);
         final jsonpet = json.encode(serializedBody);
         bodyData = jsonpet;
 
@@ -347,7 +348,8 @@ class PetApi {
             'application/xml',
         ];
 
-        final serializedBody = _serializers.serialize(pet);
+        final bodySerializer = _serializers.serializerForType(Pet);
+        final serializedBody = _serializers.serializeWith(bodySerializer, pet);
         final jsonpet = json.encode(serializedBody);
         bodyData = jsonpet;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart
index 98f0a4f507b7..ea1d9cbdd4f6 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart
@@ -207,7 +207,8 @@ class StoreApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(order);
+        final bodySerializer = _serializers.serializerForType(Order);
+        final serializedBody = _serializers.serializeWith(bodySerializer, order);
         final jsonorder = json.encode(serializedBody);
         bodyData = jsonorder;
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart
index 52a48e251df7..63865bc24438 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart
@@ -39,7 +39,8 @@ class UserApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(user);
+        final bodySerializer = _serializers.serializerForType(User);
+        final serializedBody = _serializers.serializeWith(bodySerializer, user);
         final jsonuser = json.encode(serializedBody);
         bodyData = jsonuser;
 
@@ -402,7 +403,8 @@ class UserApi {
             'application/json',
         ];
 
-        final serializedBody = _serializers.serialize(user);
+        final bodySerializer = _serializers.serializerForType(User);
+        final serializedBody = _serializers.serializeWith(bodySerializer, user);
         final jsonuser = json.encode(serializedBody);
         bodyData = jsonuser;