fixed

Sieve/Services/SieveProcessor.cs

@@ -501,13 +501,58 @@ namespace Sieve.Services
                 case FilterOperator.LessThanOrEqualTo:
                     return sResult + "<=" + value;
                 case FilterOperator.Contains:
-                    return sResult + ".Contains(" + value.ToLower() + ")";
+                    return sResult + ".Contains(" + RemoveSignAndLowerCase4VietnameseString(value) + ")";
                 case FilterOperator.StartsWith:
-                    return sResult + ".Contains(" + value.ToLower() + ")";
+                    return sResult + ".Contains(" + RemoveSignAndLowerCase4VietnameseString(value) + ")";
                 default:
                     return sResult + "=" + value;
             }
         }
+
+        
+            private static string[] VietnameseSigns = new string[]
+            {
+
+            "aAeEoOuUiIdDyY",
+
+            "áàạảãâấầậẩẫăắằặẳẵ",
+
+            "ÁÀẠẢÃÂẤẦẬẨẪĂẮẰẶẲẴ",
+
+            "éèẹẻẽêếềệểễ",
+
+            "ÉÈẸẺẼÊẾỀỆỂỄ",
+
+            "óòọỏõôốồộổỗơớờợởỡ",
+
+            "ÓÒỌỎÕÔỐỒỘỔỖƠỚỜỢỞỠ",
+
+            "úùụủũưứừựửữ",
+
+            "ÚÙỤỦŨƯỨỪỰỬỮ",
+
+            "íìịỉĩ",
+
+            "ÍÌỊỈĨ",
+
+            "đ",
+
+            "Đ",
+
+            "ýỳỵỷỹ",
+
+            "ÝỲỴỶỸ"
+            };
+            public static string RemoveSignAndLowerCase4VietnameseString(string str)
+            {
+                str = str.ToLower();
+                for (int i = 1; i < VietnameseSigns.Length; i++)
+                {
+                    for (int j = 0; j < VietnameseSigns[i].Length; j++)
+                        str = str.Replace(VietnameseSigns[i][j], VietnameseSigns[0][i - 1]);
+                }
+                return str;
+            }
             private static Expression GetExpression(TFilterTerm filterTerm, dynamic filterValue, dynamic propertyValue, bool bCaseSensitive)
         {
             switch (filterTerm.OperatorParsed)