Custom Regular expression in model property ASP.NET MVC4

Question

I need to implement a regular expression validation that allows a-z A-z 0-9 and some special characters _ - . @ &

But should restrict

\ / " : ; * ? " < > { } [ ] ( ) | ! ' % ^

tried this pattern but doesn't work.

[Required]
[Display(Name = "User name")]
[RegularExpression("^[-a-zA-Z0-9_-@]*", ErrorMessage = "Invalid characters!")]
public string UserName { get; set; }

Could you please suggest?

why have you added - two times?

Braj
– Braj

2014-08-23 08:08:27 +00:00
Commented Aug 23, 2014 at 8:08 — Braj
– Braj, Commented Aug 23, 2014 at 8:08
Nope.it is a hyphen and an underscore

Arvind897
– Arvind897

2014-08-23 08:13:12 +00:00
Commented Aug 23, 2014 at 8:13 — Arvind897
– Arvind897, Commented Aug 23, 2014 at 8:13

Braj · Accepted Answer · 2014-08-23 08:01:21Z

2

In regex hyphen has a special meaning in Character class that is used to define the range. It should be escaped or put it in the beginning or ending of the set.

Try

[-\w.@&]

Here \w match any word character [a-zA-Z0-9_]

To validate the whole string use ^ and $ to match start and end of the string respectively.

To avoid blank string try + instead of * like ^[-\w.@&]+$

answered Aug 23, 2014 at 8:01

Braj

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Comments

Rahul Tripathi · Accepted Answer · 2014-08-23 08:10:08Z

1

Try this regex:

/^[ A-Za-z0-9-.@&]*$/

REGEX DEMO

If you want to escape hyphen as starting character:

^(?!-)[A-Za-z0-9-.@&]*$

REGEX DEMO

If you want to restrict it from start and end both then try this:

^(?!-)[A-Za-z0-9-.@&]*+(?<!-)$

REGEX DEMO

edited Aug 23, 2014 at 8:10

answered Aug 23, 2014 at 7:50

Rahul Tripathi

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1 Comment

Braj Over a year ago

hyphen should be escaped or in the beginning or ending in the set.

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