diff --git a/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/Contracts/Requests/GeneratePreviewReportRequest.cs b/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/Contracts/Requests/GeneratePreviewReportRequest.cs
index 00cadf35..b65a876b 100644
--- a/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/Contracts/Requests/GeneratePreviewReportRequest.cs
+++ b/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/Contracts/Requests/GeneratePreviewReportRequest.cs
@@ -7,6 +7,23 @@ using Microsoft.SqlTools.Hosting.Protocol.Contracts;
 
 namespace Microsoft.SqlTools.ServiceLayer.TableDesigner.Contracts
 {
+    /// <summary>
+    /// The service request to generate preview report describing the changes.
+    /// </summary>
+
+    public class GeneratePreviewReportResult 
+    {
+        /// <summary>
+        /// The report generated for publish preview
+        /// </summary>
+        public string Report;
+
+        /// <summary>
+        /// format (mimetype) of the string
+        /// </summary>
+        public string MimeType;
+    }
+    
     /// <summary>
     /// The service request to generate preview report describing the changes.
     /// </summary>
@@ -15,6 +32,6 @@ namespace Microsoft.SqlTools.ServiceLayer.TableDesigner.Contracts
         /// <summary>
         /// Request definition
         /// </summary>
-        public static readonly RequestType<TableInfo, string> Type = RequestType<TableInfo, string>.Create("tabledesigner/generatepreviewreport");
+        public static readonly RequestType<TableInfo, GeneratePreviewReportResult> Type = RequestType<TableInfo, GeneratePreviewReportResult>.Create("tabledesigner/generatepreviewreport");
     }
 }
diff --git a/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/TableDesignerService.cs b/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/TableDesignerService.cs
index f038dc36..c5a6991e 100644
--- a/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/TableDesignerService.cs
+++ b/src/Microsoft.SqlTools.ServiceLayer/TableDesigner/TableDesignerService.cs
@@ -161,13 +161,17 @@ namespace Microsoft.SqlTools.ServiceLayer.TableDesigner
             });
         }
 
-        private Task HandleGeneratePreviewReportRequest(TableInfo tableInfo, RequestContext<string> requestContext)
+        private Task HandleGeneratePreviewReportRequest(TableInfo tableInfo, RequestContext<GeneratePreviewReportResult> requestContext)
         {
-            return this.HandleRequest<string>(requestContext, async () =>
+            return this.HandleRequest<GeneratePreviewReportResult>(requestContext, async () =>
             {
                 var table = this.GetTableDesigner(tableInfo);
                 var report = table.GenerateReport();
-                await requestContext.SendResult(report);
+                var generatePreviewReportResult = new GeneratePreviewReportResult();
+                // TODO - set report type by caohai
+                generatePreviewReportResult.Report = report;
+                generatePreviewReportResult.MimeType = "text/plain";
+                await requestContext.SendResult(generatePreviewReportResult);
             });
         }