Force formatting text encoded by user

I used a ViewModel class as described below:

public class ProductCreateModel
{
    [Display开发者_运维问答Name("Id product:")]
    [Required(ErrorMessage = "Please enter the id.")]
    public string IdProduct { get; set; }

    [DisplayName("Description:")]
    [Required(ErrorMessage = "Please enter the description.")]
    public string Description { get; set; }
}

How can I proceed to force users to encode an id product in format 11.111 so 2 numbers followed by dot followed by 3 numbers.

Thank you for your time.

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You could use a Regex validator:

[DisplayName("Id product:")]
[Required(ErrorMessage = "Please enter the id.")]
[RegularExpression(@"^[0-9]{2}\.[0-9]{3}$")]
public string IdProduct { get; set; }

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You can use a regular expression validation attribute like this:

[RegularExpression(@"^\d{2}\.\d{3}?$")