diff --git a/lib/codegen/csharp/rest_sharp.dart b/lib/codegen/csharp/rest_sharp.dart
index 4d53e685..ebf70787 100644
--- a/lib/codegen/csharp/rest_sharp.dart
+++ b/lib/codegen/csharp/rest_sharp.dart
@@ -40,18 +40,21 @@ class Program
 """;
   String kTemplateFormData = """
       {% if type == "text" -%}
-      request.AddParameter("{{name}}", "{{value}}", ParameterType.RequestBody);
+      request.AddParameter("{{name}}", "{{value}}", ParameterType.GetOrPost);
 {% else -%}
        request.AddFile("{{name}}", "{{value}}");
 {% endif -%}
+""";
+  String kStringFormDataOption = """
+      request.AlwaysMultipartFormData = true;
 """;
   String kTemplateJsonData = """
       var jsonBody = new {{jsonData}};
       request.AddJsonBody(jsonBody);
 """;
   String kTemplateTextData = """
-      var textBody = "{{textData}}";
-      request.AddStringBody(textBody);
+      var textBody = {{textData}};
+      request.AddStringBody(textBody, ContentType.Plain);
 """;
 
   String kStringEnd = """
@@ -144,6 +147,7 @@ class Program
             "type": data["type"]
           });
         }
+        result += kStringFormDataOption;
         result += formDataResult.substring(0, formDataResult.length - 1);
         result += kStringLineBreak;
       }
@@ -167,8 +171,8 @@ class Program
 
       if (requestModel.hasTextData) {
         jj.Template templateTextData = jj.Template(kTemplateTextData);
-        result +=
-            templateTextData.render({"textData": requestModel.requestBody});
+        result += templateTextData
+            .render({"textData": jsonEncode(requestModel.requestBody)});
         result += kStringLineBreak;
       }
 
diff --git a/test/codegen/csharp_rest_sharp_codgen_test.dart b/test/codegen/csharp_rest_sharp_codgen_test.dart
index 852ef906..52fad758 100644
--- a/test/codegen/csharp_rest_sharp_codgen_test.dart
+++ b/test/codegen/csharp_rest_sharp_codgen_test.dart
@@ -497,10 +497,8 @@ class Program
 
       request.AddHeader("Content-Type", "text/plain");
 
-      var textBody = "{
-"text": "I LOVE Flutter"
-}";
-      request.AddStringBody(textBody);
+      var textBody = "{\n\"text\": \"I LOVE Flutter\"\n}";
+      request.AddStringBody(textBody, ContentType.Plain);
 
       var response = await client.ExecuteAsync(request);
       Console.WriteLine("Status Code: " + (int)response.StatusCode);
@@ -614,9 +612,10 @@ class Program
 
       request.AddHeader("Content-Type", "multipart/form-data");
 
-      request.AddParameter("text", "API", ParameterType.RequestBody);
-      request.AddParameter("sep", "|", ParameterType.RequestBody);
-      request.AddParameter("times", "3", ParameterType.RequestBody);
+      request.AlwaysMultipartFormData = true;
+      request.AddParameter("text", "API", ParameterType.GetOrPost);
+      request.AddParameter("sep", "|", ParameterType.GetOrPost);
+      request.AddParameter("times", "3", ParameterType.GetOrPost);
 
       var response = await client.ExecuteAsync(request);
       Console.WriteLine("Status Code: " + (int)response.StatusCode);
@@ -651,9 +650,10 @@ class Program
       request.AddHeader("Content-Type", "multipart/form-data");
       request.AddHeader("User-Agent", "Test Agent");
 
-      request.AddParameter("text", "API", ParameterType.RequestBody);
-      request.AddParameter("sep", "|", ParameterType.RequestBody);
-      request.AddParameter("times", "3", ParameterType.RequestBody);
+      request.AlwaysMultipartFormData = true;
+      request.AddParameter("text", "API", ParameterType.GetOrPost);
+      request.AddParameter("sep", "|", ParameterType.GetOrPost);
+      request.AddParameter("times", "3", ParameterType.GetOrPost);
 
       var response = await client.ExecuteAsync(request);
       Console.WriteLine("Status Code: " + (int)response.StatusCode);
@@ -687,7 +687,8 @@ class Program
 
       request.AddHeader("Content-Type", "multipart/form-data");
 
-      request.AddParameter("token", "xyz", ParameterType.RequestBody);
+      request.AlwaysMultipartFormData = true;
+      request.AddParameter("token", "xyz", ParameterType.GetOrPost);
       request.AddFile("imfile", "/Documents/up/1.png");
 
       var response = await client.ExecuteAsync(request);
@@ -722,7 +723,8 @@ class Program
 
       request.AddHeader("Content-Type", "multipart/form-data");
 
-      request.AddParameter("token", "xyz", ParameterType.RequestBody);
+      request.AlwaysMultipartFormData = true;
+      request.AddParameter("token", "xyz", ParameterType.GetOrPost);
       request.AddFile("imfile", "/Documents/up/1.png");
 
       var response = await client.ExecuteAsync(request);
@@ -760,9 +762,10 @@ class Program
 
       request.AddHeader("Content-Type", "multipart/form-data");
 
-      request.AddParameter("text", "API", ParameterType.RequestBody);
-      request.AddParameter("sep", "|", ParameterType.RequestBody);
-      request.AddParameter("times", "3", ParameterType.RequestBody);
+      request.AlwaysMultipartFormData = true;
+      request.AddParameter("text", "API", ParameterType.GetOrPost);
+      request.AddParameter("sep", "|", ParameterType.GetOrPost);
+      request.AddParameter("times", "3", ParameterType.GetOrPost);
 
       var response = await client.ExecuteAsync(request);
       Console.WriteLine("Status Code: " + (int)response.StatusCode);
@@ -801,7 +804,8 @@ class Program
       request.AddHeader("User-Agent", "Test Agent");
       request.AddHeader("Keep-Alive", "true");
 
-      request.AddParameter("token", "xyz", ParameterType.RequestBody);
+      request.AlwaysMultipartFormData = true;
+      request.AddParameter("token", "xyz", ParameterType.GetOrPost);
       request.AddFile("imfile", "/Documents/up/1.png");
 
       var response = await client.ExecuteAsync(request);