public static string FromAlphabet(AlphabetSection model)
        {
            if (model.category == "All")
            {
                regexp = "A-Za-z";
            }
            else if (model.category == "Capital")
            {
                regexp = "A-Z";
            }
            else if (model.category == "Small")
            {
                regexp = "a-z";
            }
            else if (model.category == "CustomAlphabet")
            {
                regexp = FromCustomeAlphabet(model.customAlphabet);
            }
            else if (model.category == "CustomText")
            {
                regexp = "(" + model.customText + ")";
            }

            return(regexp);
        }
        public static string FromAtLeastOne(AlphabetSection model, bool isOk)
        {
            string atleast = "";

            if ((model.atLeastOneCapital) && (model.atLeastOneSmall))
            {
                atleast = atleast + "a-zA-Z";
            }
            else if (model.atLeastOneCapital)
            {
                atleast = atleast + "A-Z";
            }
            else if (model.atLeastOneSmall)
            {
                atleast = atleast + "a-z";
            }

            return(atleast);
        }
        public static string FromAtLeastOne(AlphabetSection model)
        {
            string atleast = "";

            if ((model.atLeastOneCapital) && (model.atLeastOneSmall))
            {
                atleast = atleast + "(?=.*[A-Z])(?=.*[a-z])";
            }
            else if (model.atLeastOneCapital)
            {
                atleast = atleast + "(?=.*A-Z])";
            }
            else if (model.atLeastOneSmall)
            {
                atleast = atleast + "(?=.*[a-z])";
            }

            return(atleast);
        }