[dart-dio] Fix parameter generation problems (#10061)

* fix parameter with list of `MultipartFile` being generated as single `MultipartFile`
* generate serializer factories for all container params, not only body params
* fix compilation errors when `skipFormModel=false`

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

@@ -20,6 +20,7 @@ import com.google.common.collect.Sets;
 import io.swagger.v3.oas.models.media.Schema;
 import org.apache.commons.lang3.StringUtils;
 import org.openapitools.codegen.*;
+import org.openapitools.codegen.config.GlobalSettings;
 import org.openapitools.codegen.meta.GeneratorMetadata;
 import org.openapitools.codegen.meta.Stability;
 import org.openapitools.codegen.meta.features.ClientModificationFeature;
@@ -317,13 +318,23 @@ public class DartDioNextClientCodegen extends AbstractDartCodegen {
         for (CodegenOperation op : operationList) {
             for (CodegenParameter param : op.allParams) {
                 if (((op.isMultipart && param.isFormParam) || param.isBodyParam) && (param.isBinary || param.isFile)) {
-                    param.baseType = "MultipartFile";
+                    param.dataType = param.dataType.replace("Uint8List", "MultipartFile");
-                    param.dataType = "MultipartFile";
+                    param.baseType = param.baseType.replace("Uint8List", "MultipartFile");
                     op.imports.add("MultipartFile");
+
+                    if (SERIALIZATION_LIBRARY_BUILT_VALUE.equals(library)) {
+                        boolean skipFormModel = Boolean.parseBoolean(GlobalSettings.getProperty(CodegenConstants.SKIP_FORM_MODEL, "true"));
+                        if (param.isFormParam && param.isContainer && !skipFormModel) {
+                            // Because of skipFormModel=false, there is a model class generated which has
+                            // "BuiltList<Uint8List>" as property and it requires the correct
+                            // serializer imports to be added in order to compile.
+                            addBuiltValueSerializerImport("Uint8List");
+                        }
+                    }
                 }
             }
 
-            // the MultipartFile handling above changes the type of some parameters from
+            // The MultipartFile handling above changes the type of some parameters from
             // `UInt8List`, the default for files, to `MultipartFile`.
             //
             // The following block removes the required import for Uint8List if it is no
@@ -335,8 +346,10 @@ public class DartDioNextClientCodegen extends AbstractDartCodegen {
                 op.imports.remove("Uint8List");
             }
 
-            for (CodegenParameter param : op.bodyParams) {
+            for (CodegenParameter param : op.allParams) {
-                if (param.isContainer) {
+                // Generate serializer factories for all container type parameters.
+                // But skip binary and file parameters, JSON serializers don't make sense there.
+                if (param.isContainer && !(param.isBinary || param.isFile )) {
                     final Map<String, Object> serializer = new HashMap<>();
                     serializer.put("isArray", param.isArray);
                     serializer.put("uniqueItems", param.uniqueItems);
@@ -351,7 +364,9 @@ public class DartDioNextClientCodegen extends AbstractDartCodegen {
                 resultImports.add("package:" + pubName + "/src/api_util.dart");
             }
 
-            if (op.returnContainer != null) {
+            // Generate serializer factories for response types.
+            // But skip binary and file response, JSON serializers don't make sense there.
+            if (op.returnContainer != null && !(op.isResponseBinary || op.isResponseFile)) {
                 final Map<String, Object> serializer = new HashMap<>();
                 serializer.put("isArray", Objects.equals("array", op.returnContainer) || Objects.equals("set", op.returnContainer));
                 serializer.put("uniqueItems", op.uniqueItems);
@@ -367,6 +382,14 @@ public class DartDioNextClientCodegen extends AbstractDartCodegen {
         return objs;
     }
 
+    private void addBuiltValueSerializerImport(String type) {
+        additionalProperties.compute("builtValueSerializerImports", (k, v) -> {
+            Set<String> imports = v == null ? Sets.newHashSet() : ((Set<String>) v);
+            imports.addAll(rewriteImports(Sets.newHashSet(type), true));
+            return imports;
+        });
+    }
+
     private Set<String> rewriteImports(Set<String> originalImports, boolean isModel) {
         Set<String> resultImports = Sets.newHashSet();
         for (String modelImport : originalImports) {

modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/serialize.mustache

@@ -2,7 +2,7 @@
       {{#isMultipart}}
       _bodyData = FormData.fromMap(<String, dynamic>{
         {{#formParams}}
-        {{^required}}{{^isNullable}}if ({{{paramName}}} != null) {{/isNullable}}{{/required}}r'{{{baseName}}}': {{#isFile}}{{{paramName}}}{{/isFile}}{{^isFile}}encodeFormParameter(_serializers, {{{paramName}}}, const FullType({{^isContainer}}{{{baseType}}}{{/isContainer}}{{#isContainer}}Built{{#isMap}}Map{{/isMap}}{{#isArray}}{{#uniqueItems}}Set{{/uniqueItems}}{{^uniqueItems}}List{{/uniqueItems}}{{/isArray}}, [{{#isMap}}FullType(String), {{/isMap}}FullType({{{baseType}}})]{{/isContainer}})){{/isFile}},
+        {{^required}}{{^isNullable}}if ({{{paramName}}} != null) {{/isNullable}}{{/required}}r'{{{baseName}}}': {{#isFile}}{{{paramName}}}{{#isArray}}.toList(){{/isArray}}{{/isFile}}{{^isFile}}encodeFormParameter(_serializers, {{{paramName}}}, const FullType({{^isContainer}}{{{baseType}}}{{/isContainer}}{{#isContainer}}Built{{#isMap}}Map{{/isMap}}{{#isArray}}{{#uniqueItems}}Set{{/uniqueItems}}{{^uniqueItems}}List{{/uniqueItems}}{{/isArray}}, [{{#isMap}}FullType(String), {{/isMap}}FullType({{{baseType}}})]{{/isContainer}})){{/isFile}},
         {{/formParams}}
       });
       {{/isMultipart}}

modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/serializers.mustache

@@ -11,7 +11,9 @@ import 'package:{{pubName}}/src/model/date.dart';{{/useDateLibCore}}
 {{#useDateLibTimeMachine}}import 'package:time_machine/time_machine.dart';
 import 'package:{{pubName}}/src/offset_date_serializer.dart';{{/useDateLibTimeMachine}}
 {{#models}}{{#model}}import 'package:{{pubName}}/src/model/{{classFilename}}.dart';
-{{/model}}{{/models}}
+{{/model}}{{/models}}{{#builtValueSerializerImports}}import '{{{.}}}';
+{{/builtValueSerializerImports}}
+
 part 'serializers.g.dart';
 
 @SerializersFor([{{#models}}{{#model}}

samples/openapi3/client/petstore/dart-dio-next/petstore_client_lib_fake/lib/src/serializers.dart

@@ -110,14 +110,26 @@ part 'serializers.g.dart';
   User,
 ])
 Serializers serializers = (_$serializers.toBuilder()
+      ..addBuilderFactory(
+        const FullType(BuiltList, [FullType(String)]),
+        () => ListBuilder<String>(),
+      )
       ..addBuilderFactory(
         const FullType(BuiltMap, [FullType(String), FullType(String)]),
         () => MapBuilder<String, String>(),
       )
+      ..addBuilderFactory(
+        const FullType(BuiltList, [FullType(String)]),
+        () => ListBuilder<String>(),
+      )
       ..addBuilderFactory(
         const FullType(BuiltSet, [FullType(Pet)]),
         () => SetBuilder<Pet>(),
       )
+      ..addBuilderFactory(
+        const FullType(BuiltSet, [FullType(String)]),
+        () => SetBuilder<String>(),
+      )
       ..addBuilderFactory(
         const FullType(BuiltList, [FullType(Pet)]),
         () => ListBuilder<Pet>(),