public override string Validate(string propertyName) { if (!DoValidation) { return(null); } switch (propertyName) { case nameof(SkillName): if (SkillName.IsNullOrWhiteSpace()) { return(string.Format(Constants.FieldMustBeFilledMessageFormat, nameof(SkillName))); } else if (!SkillName.IsLengthBetween(2, 50)) { return(string.Format(Constants.LengthErrorMessageFormat, nameof(SkillName), 2, 50)); } break; } return(null); }