[dart-dio] Fixes issues around formData

Author: josh-burton

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

@@ -197,6 +197,8 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("pubspec.mustache", "", "pubspec.yaml"));
         supportingFiles.add(new SupportingFile("analysis_options.mustache", "", "analysis_options.yaml"));
         supportingFiles.add(new SupportingFile("apilib.mustache", libFolder, "api.dart"));
+        supportingFiles.add(new SupportingFile("api_util.mustache", libFolder, "api_util.dart"));
+
         supportingFiles.add(new SupportingFile("serializers.mustache", libFolder, "serializers.dart"));
 
         supportingFiles.add(new SupportingFile("gitignore.mustache", "", ".gitignore"));
@@ -304,6 +306,10 @@ public Map<String, Object> postProcessOperationsWithModels(Map<String, Object> o
             op.vendorExtensions.put("isForm", isForm);
             op.vendorExtensions.put("isMultipart", isMultipart);
 
+            if (op.getHasFormParams()) {
+                fullImports.add("package:" + pubName + "/api_util.dart");
+            }
+
             Set<String> imports = new HashSet<>();
             for (String item : op.imports) {
                 if (!modelToIgnore.contains(item.toLowerCase(Locale.ROOT))) {
@@ -314,6 +320,7 @@ public Map<String, Object> postProcessOperationsWithModels(Map<String, Object> o
             }
             modelImports.addAll(imports);
             op.imports = imports;
+
         }
 
         objs.put("modelImports", modelImports);

modules/openapi-generator/src/main/resources/dart-dio/api.mustache

@@ -40,9 +40,9 @@ class {{classname}} {
 
         List<String> contentTypes = [{{#consumes}}"{{{mediaType}}}"{{#hasMore}},{{/hasMore}}{{/consumes}}];
 
-
-        {{#formParams}}
+        {{#hasFormParams}}
         Map<String, dynamic> formData = {};
+        {{#formParams}}
         {{#isMultipart}}
             {{^isFile}}
                 if ({{paramName}} != null) {
@@ -55,8 +55,9 @@ class {{classname}} {
                 }
             {{/isFile}}
         {{/isMultipart}}
-        bodyData = FormData.fromMap(formData);
         {{/formParams}}
+        bodyData = FormData.fromMap(formData);
+        {{/hasFormParams}}
 
         {{#bodyParam}}
             {{#isListContainer}}

modules/openapi-generator/src/main/resources/dart-dio/api_util.mustache

@@ -0,0 +1,18 @@
+/// Format the given parameter object into string.
+String parameterToString(dynamic value) {
+  if (value == null) {
+    return '';
+  } else if (value is DateTime) {
+    return value.toUtc().toIso8601String();
+  {{#models}}
+    {{#model}}
+      {{#isEnum}}
+  } else if (value is {{classname}}) {
+    return {{classname}}TypeTransformer().encode(value).toString();
+      {{/isEnum}}
+    {{/model}}
+  {{/models}}
+  } else {
+    return value.toString();
+  }
+}