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Localizing/Overriding ASP.NET Identity 3 Error Messages in ASP.NET Core

 

        Introduction:

 

                 If you ever develop an app with modern ASP.NET Identity framework then you know that at specific condition ASP.NET Identity returns some specific errors. For example, if email is invalid then framework will return Email 'x@y.com' is invalid message. These error messages are great but what if you want to override these error message. For example, if you are developing multi-lingual site then these error messages does not make any sense. ASP.NET Identity 3 makes it very easy to override/localize these identity error messages. There was no easy way to override these messages in ASP.NET Identity 2.x.x. In-fact 2 years ago, I opened an issue at codeplex. The issue was closed and then re-opened because the team now is planning to port this functionality form version 3 to version 2. In this post, I will show you how we can override these error messages in ASP.NET Identity 3.  

 

        Description:

 

                    Note that I am using beta5 at the time of writing. We just need add a class inheriting from IdentityErrorDescriber class, 

 

view sourceprint?
001 public class MyIdentityErrorDescriber : IdentityErrorDescriber
002 {
003     public MyIdentityErrorDescriber()
004     {
005     }
006  
007     public override IdentityError ConcurrencyFailure()
008     {
009         //return new IdentityError
010         //{
011         //    Code = nameof(ConcurrencyFailure),
012         //    Description = Resources.ConcurrencyFailure
013         //};
014         return base.ConcurrencyFailure();
015     }
016  
017     public override IdentityError DefaultError()
018     {
019         return base.DefaultError();
020     }
021  
022     public override IdentityError DuplicateEmail(string email)
023     {
024         return base.DuplicateEmail(email);
025     }
026  
027     public override IdentityError DuplicateRoleName(string name)
028     {
029         return base.DuplicateRoleName(name);
030     }
031  
032     public override IdentityError DuplicateUserName(string name)
033     {
034         return base.DuplicateUserName(name);
035     }
036  
037     public override IdentityError InvalidEmail(string email)
038     {
039         return base.InvalidEmail(email);
040     }
041  
042     public override IdentityError InvalidRoleName(string name)
043     {
044         return base.InvalidRoleName(name);
045     }
046  
047     public override IdentityError InvalidToken()
048     {
049         return base.InvalidToken();
050     }
051  
052     public override IdentityError InvalidUserName(string name)
053     {
054         return base.InvalidUserName(name);
055     }
056  
057     public override IdentityError LoginAlreadyAssociated()
058     {
059         return base.LoginAlreadyAssociated();
060     }
061  
062     public override IdentityError PasswordMismatch()
063     {
064         return base.PasswordMismatch();
065     }
066  
067     public override IdentityError PasswordRequiresDigit()
068     {
069         return base.PasswordRequiresDigit();
070     }
071  
072     public override IdentityError PasswordRequiresLower()
073     {
074         return base.PasswordRequiresLower();
075     }
076  
077     public override IdentityError PasswordRequiresNonLetterAndDigit()
078     {
079         return base.PasswordRequiresNonLetterAndDigit();
080     }
081  
082     public override IdentityError PasswordRequiresUpper()
083     {
084         return base.PasswordRequiresUpper();
085     }
086  
087     public override IdentityError PasswordTooShort(int length)
088     {
089         return base.PasswordTooShort(length);
090     }
091  
092     public override IdentityError UserAlreadyHasPassword()
093     {
094         return base.UserAlreadyHasPassword();
095     }
096  
097     public override IdentityError UserAlreadyInRole(string role)
098     {
099         return base.UserAlreadyInRole(role);
100     }
101  
102     public override IdentityError UserLockoutNotEnabled()
103     {
104         return base.UserLockoutNotEnabled();
105     }
106  
107     public override IdentityError UserNotInRole(string role)
108     {
109         return base.UserNotInRole(role);
110     }
111 }

 

                    For each error, we just need to return IdentityError object which include Code and Description properties. Code is a short-error-message and Description include the details of the error. In real world application, we can get the error-messages from resource files. Currently, there is very little support of localization(including ASP.NET Core application cannot add resx file from Visual Studio). But its coming. Now we just need to register this class in Startup.ConfigureServices method,

 

view sourceprint?
1 services.AddTransient<IdentityErrorDescriber, MyIdentityErrorDescriber>();

 

        Summary:

 

                    ASP.NET Identity 3 makes it very easy to override the internal error messages that framework returns during validation. In this article, I showed you how we can localize these error messages.

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