Question

I have the following code working

    [Required(ErrorMessage = "Price is required.")]
    [Range(typeof(Decimal), "1", "9999", ErrorMessage = "Price xx.xx")]
    public decimal? productPrice { get; set; }

When the page is submitted with
Price = EMPTY Field error message is “Price is required.”.
Price = over 9999 error message is “Price xx.xx”.

However, when I type ‘aaaa’ the error message is
“The field productPrice must be a number.”

How can I change the message if type in not correct?
Like : “Price must be a decimal/number between 1-9999.

—- UPDATE: —-
The below code worked with

NULL, Not Decimal, Between Range, BUT not working with “.1”.

    [Required(ErrorMessage = "Price is required.")]
    [RegularExpression(@"[0-9]*\.?[0-9]+", ErrorMessage = "Price must be a Numbers only.")]
    [Range(typeof(Decimal), "1", "9999", ErrorMessage = "Price must be a decimal/number between {1} and {2}.")]
    public decimal? productPrice { get; set; }

Answer 1

You can try with the regular expression:

[RegularExpression(@"[0-9]*\.?[0-9]+", ErrorMessage = "{0} must be a Number.")]

you can also try the Data Annotations Extensions:
http://dataannotationsextensions.org/Home/Wiki

Or write your own implementation,something like this :
https://github.com/srkirkland/DataAnnotationsExtensions/blob/master/DataAnnotationsExtensions/DigitsAttribute.cs

UPDATE
With REGEX (Matches $9,999.99 | $0.70 | .1)

[RegularExpression(@"^\$?([1-9]{1}[0-9]{0,2}(\,[0-9]{3})*(\.[0-9]{0,2})?|[1-9]{1}[0-9]{0,}(\.[0-9]{0,2})?|0(\.[0-9]{0,2})?|(\.[0-9]{1,2})?)$", ErrorMessage = "{0} must be a Number.")]

Or using Range with a slight modification to @Martin suggestion (actually is a better solution):

[Range(typeof(Decimal), "0", "9999", ErrorMessage = "{0} must be a decimal/number between {1} and {2}.")]