c# - Using parameter for StringLength attribute -

the code generated asp.net mvc 3 membership, escpecially property newpassword of class changepasswordmodel looks like:

    [required]     [stringlength(100, minimumlength=6)]     [datatype(datatype.password)]     [display("name = currentpassword")]     public string newpassword { get; set; } 

in order to fill information external parameters using recourcetype:
(in case changing oldpassword , fill attribute display additional data resource

    [required]     [datatype(datatype.password)]     [display(resourcetype = typeof(account), name = "changepasswordcurrent")]     public string oldpassword { get; set; } 

back newpassword. how can substitute minimumlenght membership.minrequiredpasswordlength? : attempt:

    [required]     [stringlength(100, minimumlength=membership.minrequiredpasswordlength)]      [datatype(datatype.password)]     [display(resourcetype=typeof(account), name= "changepasswordnew")]     public string newpassword { get; set; } 

this produces error:

an attribute argument must constant expression, typeof expression or array creation expression of attribute parameter type (http://msdn.microsoft.com/de-de/library/09ze6t76%28v=vs.90%29.aspx)

validation attributes must compiled constants (like error message states). create own validationattribute handles minimum length you.

[attributeusage(attributetargets.field | attributetargets.property, allowmultiple = false, inherited = true)] public sealed class validatepasswordlengthattribute : validationattribute {      private const string defaulterrormessage = "'{0}' must @ least {1} characters long.";      private readonly int _mincharacters = membership.provider.minrequiredpasswordlength;     public validatepasswordlengthattribute() : base(defaulterrormessage)     {     }      public override string formaterrormessage(string name)     {         return string.format(cultureinfo.currentuiculture, errormessagestring, name, _mincharacters);     }      public override bool isvalid(object value)     {         var valueasstring = value.tostring();         return (valueasstring != null) && (valueasstring.length >= _mincharacters);     } } 

then view model (you more fancy , add max length part of dataannotations in validatepasswordlength attribute remove line)

[required] [stringlength(100)]  [datatype(datatype.password)] [display(resourcetype=typeof(account), name= "changepasswordnew")] [validatepasswordlength] public string newpassword { get; set; }