Validate decimal value to 2 decimal places with da

问题:

I have this in my view model:

[Required(ErrorMessage = "Price is required")]
[Range(0.01, 999999999, ErrorMessage = "Price must be greater than 0.00")]
[DisplayName("Price ($)")]
public decimal Price { get; set; }

I'd like to validate that the user doesn't enter more than 2 decimal places. So I'd like to have

Valid values: 12, 12.3, 12.34

Invalid values: 12., 12.345

Is there a way to validate this with a data annotation?

回答1:

You could use the RegularExpression attribute, with a regex that matches your criteria. There are a whole bunch of expressions here that involve numbers, I'm sure one will fit the bill. Here is the link.

This will get you started, though it may not be as inclusive as you want (requires at least one digit leading the decimal point):

[RegularExpression(@"\d+(\.\d{1,2})?", ErrorMessage = "Invalid price")]

Note that it is difficult to emit a precise error message because you don't know which part of the regex failed to match (the string "z.22" has the correct number of decimal places, for example, but is not a valid price).

回答2:

[RegularExpression(@"^\d+.\d{0,2}$",ErrorMessage = "Price can't have more than 2 decimal places")]
public decimal Price { get; set; }

This will cater for 0 to 2 decimal places, or none at all.

回答3:

[RegularExpression(@"^\d+(\.\d)?$", ErrorMessage = "It cannot have more than one decimal point value")]
[Range( 0.1,100)]
public double xyz{get;set;}         

It works for me upto one decimal value

回答4:

You can also create your own Decimal validation attribute, inheriting from RegularExpressionAttribute:

 public class DecimalAttribute : RegularExpressionAttribute
 {
    public int DecimalPlaces { get; set; }
    public DecimalAttribute(int decimalPlaces)
        : base(string.Format(@"^\d*\.?\d{{0,{0}}}$", decimalPlaces))
    {
        DecimalPlaces = decimalPlaces;
    }

    public override string FormatErrorMessage(string name)
    {
        return string.Format("This number can have maximum {0} decimal places", DecimalPlaces);
    }
 }

and register it to enable client-side validation in Application_Start():

DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(DecimalAttribute), typeof(RegularExpressionAttributeAdapter));

回答5:

You can make this validation by using a regular expression and apply it with RegularExpression attribute.

回答6:

I had the same scenario as the OP, yet the answers provided don't give a solution that works for all of the following cases:

12, 12.3 and 12.34

To do that, we use the following regular expression:

[RegularExpression(@"^\d+(.\d{1,2})?$")]

回答7:

Similar to mattytommo. You need to escape '.' - otherwise ANY character will be accepted

[RegularExpression(@"^\d+(\.\d{1,2})?$")]