Validating model with regular expression

Question

Hi I am using a validation like below to ensure I am just working on a csv file.

 [RegularExpression(@"(csv)|(CSV)")]
 public string AttachmentFileName { get; set; }

After form submit model returns a value

AttachmentFileName = "UserMapping.csv"

However I am still getting validation error as:

The field AttachmentFileName must match the regular expression '(csv)|(CSV)'.

Where I am doing error? I tested my expression on website, there it seems to work alright.

Answer 1

You may fix it by matching the whole string (RegularExpressionAttribute requires a full string match):

[RegularExpression(@"^.*[.][cC][sS][vV]$")]
public string AttachmentFileName { get; set; }

The ^.*[.][cC][sS][vV]$ pattern matches

• ^ - start of string
• .* - any 0+ chars
• [.] - a dot
• [cC][sS][vV] - csv (case insensitive)
• $ - end of string.