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I want to use a 'static readonly' field from a Settings class, this is where all my hardcoded code is, such as error messages and constants, in a [StringLength] attribute for a ViewModel. However, StringLength, does not accept attribute arguments that aren't constant expression, typeof expression or array expressions. However the field I use cannot be changed to a constant expression because it uses other constant fields and thus gives an error.

I know there's a way around this by using the string and constant expression

The reason why I want this is because it will make things very easy changable in the future if I were to change some hardcoded code. The hardcoded code is used in multiple locations such as model classes and view models, since they have the same requirements.

I tried using a property getter for this field that is a constant but that doesn't seem to work either. I've googled and looked here on stackoverflow, but can't quite seem to find anyone with the exact same issue.

I also tried using a string.Format() as argument, althought this is NOT the solution I want because then I still have to change this message in multiple locations.

The error occurs for Settings.LastNameLength in the line of StringLength.

    public class DeelnemerViewModels
    {
...
        [Display (Name = "Lastname", Prompt = "Doe")]
        [Required (ErrorMessage = Settings.fieldNeeded)]
        [StringLength (Settings.maxAmountOfCharactersLastName, MinimumLength = Settings.minAmountOfCharactersLastname, ErrorMessage = Settings.LastNameLength)]
        public string Lastname { get; set; }
...

    }

    public static class Settings
    {
...
        public const int minAmountOfCharactersLastname = 2;
        public const int maxAmountOfCharactersLastName = 50;

        public static readonly string LastNameLength =
            "The lastname does not fit the requirements. The lastname must atleast be "
            + minAmountOfCharactersLastname + " characters long and at max "
            + maxAmountOfCharactersLastName + " characters long.";
...
    }
Ruben Szekér
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    How is this different from the question you asked the other day? https://stackoverflow.com/q/55742092/491907 you can only use constants, Types or arrays of Constants/Types – pinkfloydx33 Apr 19 '19 at 09:19
  • It's different since I cannot convert this static readonly to a cons because then it gives the error that a constant cannot use other consts, therefore it doesn't work. – Ruben Szekér Apr 19 '19 at 11:32

0 Answers0