Add non-GUID/string primary keys support for OpenIddictToken and add new log messages

samples/Mvc.Server/Startup.cs

@@ -142,7 +142,7 @@ namespace Mvc.Server {
                     // context.Applications.Add(new OpenIddictApplication {
                     //     Id = "resource_server",
                     //     DisplayName = "Main resource server",
-                    //     Secret = "875sqd4s5d748z78z7ds1ff8zz8814ff88ed8ea4z4zzd",
+                    //     Secret = Crypto.HashPassword("secret_secret_secret"),
                     //     Type = OpenIddictConstants.ClientTypes.Confidential
                     // });
 

src/OpenIddict.Core/Infrastructure/OpenIddictProvider.Revocation.cs

@@ -5,11 +5,13 @@
  */
 
 using System;
+using System.Diagnostics;
 using System.Threading.Tasks;
 using AspNet.Security.OpenIdConnect.Extensions;
 using AspNet.Security.OpenIdConnect.Server;
 using JetBrains.Annotations;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 
 namespace OpenIddict.Infrastructure {
     public partial class OpenIddictProvider<TUser, TApplication, TAuthorization, TScope, TToken> : OpenIdConnectServerProvider
@@ -88,24 +90,24 @@ namespace OpenIddict.Infrastructure {
             // If the received token is not a refresh token, set Revoked
             // to false to indicate that the token cannot be revoked.
             if (!context.Ticket.IsRefreshToken()) {
+                services.Logger.LogError("The revocation request was rejected because the token was not a refresh token.");
+
                 context.Revoked = false;
 
                 return;
             }
 
             // Extract the token identifier from the authentication ticket.
-            // If the identifier cannot be extracted, abort the revocation.
             var identifier = context.Ticket.GetTicketId();
-            if (string.IsNullOrEmpty(identifier)) {
+            Debug.Assert(!string.IsNullOrEmpty(identifier),
-                context.Revoked = true;
+                "The refresh token should contain a ticket identifier.");
-
-                return;
-            }
 
             // Retrieve the token from the database. If the token cannot be found,
             // assume it is invalid and consider the revocation as successful.
             var token = await services.Tokens.FindByIdAsync(identifier);
             if (token == null) {
+                services.Logger.LogInformation("The refresh token '{Identifier}' was already revoked.", identifier);
+
                 context.Revoked = true;
 
                 return;
@@ -114,6 +116,8 @@ namespace OpenIddict.Infrastructure {
             // Revoke the refresh token.
             await services.Tokens.RevokeAsync(token);
 
+            services.Logger.LogInformation("The refresh token '{Identifier}' was revoked.", identifier);
+
             context.Revoked = true;
         }
     }

src/OpenIddict.Core/Infrastructure/OpenIddictProvider.Serialization.cs

@@ -4,7 +4,7 @@
  * the license and the contributors participating to this project.
  */
 
-using System.Diagnostics;
+using System;
 using System.Threading.Tasks;
 using AspNet.Security.OpenIdConnect.Extensions;
 using AspNet.Security.OpenIdConnect.Server;
@@ -17,14 +17,16 @@ namespace OpenIddict.Infrastructure {
         public override async Task SerializeRefreshToken([NotNull] SerializeRefreshTokenContext context) {
             var services = context.HttpContext.RequestServices.GetRequiredService<OpenIddictServices<TUser, TApplication, TAuthorization, TScope, TToken>>();
 
-            // Note: the identifier cannot be null as it's always
+            // Persist a new token entry in the database.
-            // generated by the OpenID Connect server middleware
+            var identifier = await services.Tokens.CreateAsync(OpenIdConnectConstants.TokenTypeHints.RefreshToken);
-            // before invoking the SerializeRefreshToken event.
+            if (string.IsNullOrEmpty(identifier)) {
-            Debug.Assert(!string.IsNullOrEmpty(context.Ticket.GetTicketId()),
+                throw new InvalidOperationException("The unique key associated with a refresh token cannot be null or empty.");
-                "The unique identifier associated with the refresh token was missing or empty.");
+            }
 
-            // Only persist the refresh token identifier in the database.
+            // Attach the key returned by the underlying store
-            await services.Tokens.CreateAsync(context.Ticket.GetTicketId(), OpenIdConnectConstants.TokenTypeHints.RefreshToken);
+            // to the refresh token to override the default GUID
+            // generated by the OpenID Connect server middleware.
+            context.Ticket.SetTicketId(identifier);
         }
     }
 }

src/OpenIddict.Core/Managers/OpenIddictApplicationManager.cs

@@ -52,8 +52,11 @@ namespace OpenIddict {
         /// Creates a new application.
         /// </summary>
         /// <param name="application">The application to create.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
-        public virtual Task CreateAsync(TApplication application) {
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the unique identifier associated with the application.
+        /// </returns>
+        public virtual Task<string> CreateAsync(TApplication application) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -65,7 +68,10 @@ namespace OpenIddict {
         /// Retrieves an application using its unique identifier.
         /// </summary>
         /// <param name="identifier">The unique identifier associated with the application.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the client application corresponding to the identifier.
+        /// </returns>
         public virtual Task<TApplication> FindByIdAsync(string identifier) {
             return Store.FindByIdAsync(identifier, CancellationToken);
         }
@@ -74,7 +80,10 @@ namespace OpenIddict {
         /// Retrieves an application using its post_logout_redirect_uri.
         /// </summary>
         /// <param name="url">The post_logout_redirect_uri associated with the application.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation, whose result
+        /// returns the client application corresponding to the post_logout_redirect_uri.
+        /// </returns>
         public virtual Task<TApplication> FindByLogoutRedirectUri(string url) {
             return Store.FindByLogoutRedirectUri(url, CancellationToken);
         }
@@ -83,7 +92,10 @@ namespace OpenIddict {
         /// Retrieves the client type associated with an application.
         /// </summary>
         /// <param name="application">The application.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the client type of the application (by default, "public").
+        /// </returns>
         public virtual async Task<string> GetClientTypeAsync(TApplication application) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
@@ -105,7 +117,10 @@ namespace OpenIddict {
         /// Retrieves the display name associated with an application.
         /// </summary>
         /// <param name="application">The application.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the display name associated with the application.
+        /// </returns>
         public virtual Task<string> GetDisplayNameAsync(TApplication application) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
@@ -119,7 +134,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="address">The address that should be compared to the redirect_uri stored in the database.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns a boolean indicating whether the redirect_uri was valid.
+        /// </returns>
         public virtual async Task<bool> ValidateRedirectUriAsync(TApplication application, string address) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
@@ -141,6 +159,10 @@ namespace OpenIddict {
         /// <param name="application">The application.</param>
         /// <param name="secret">The secret that should be compared to the client_secret stored in the database.</param>
         /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns a boolean indicating whether the client secret was valid.
+        /// </returns>
         public virtual async Task<bool> ValidateSecretAsync(TApplication application, string secret) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));

src/OpenIddict.Core/Managers/OpenIddictTokenManager.cs

@@ -75,7 +75,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="user">The user corresponding to the identity.</param>
         /// <param name="scopes">The scopes granted by the resource owner.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the <see cref="ClaimsIdentity"/> corresponding to the user.
+        /// </returns>
         public virtual async Task<ClaimsIdentity> CreateIdentityAsync(TUser user, IEnumerable<string> scopes) {
             if (user == null) {
                 throw new ArgumentNullException(nameof(user));
@@ -145,26 +148,27 @@ namespace OpenIddict {
         /// <summary>
         /// Creates a new token, defined by a unique identifier and a token type.
         /// </summary>
-        /// <param name="identifier">The unique identifier associated with the token to create.</param>
         /// <param name="type">The token type.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
-        public virtual Task CreateAsync(string identifier, string type) {
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
-            if (string.IsNullOrEmpty(identifier)) {
+        /// whose result returns the unique identifier associated with the token.
-                throw new ArgumentException("The identifier cannot be null or empty", nameof(identifier));
+        /// </returns>
-            }
+        public virtual Task<string> CreateAsync(string type) {
-
             if (string.IsNullOrEmpty(type)) {
                 throw new ArgumentException("The token type cannot be null or empty", nameof(type));
             }
 
-            return Store.CreateAsync(identifier, type, CancellationToken);
+            return Store.CreateAsync(type, CancellationToken);
         }
 
         /// <summary>
-        /// Retrieves an token using its unique identifier.
+        /// Retrieves a token using its unique identifier.
         /// </summary>
         /// <param name="identifier">The unique identifier associated with the token.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the token corresponding to the unique identifier.
+        /// </returns>
         public virtual Task<TToken> FindByIdAsync(string identifier) {
             if (string.IsNullOrEmpty(identifier)) {
                 throw new ArgumentException("The identifier cannot be null or empty", nameof(identifier));

src/OpenIddict.Core/Stores/IOpenIddictApplicationStore.cs

@@ -18,15 +18,21 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application to create.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
-        Task CreateAsync(TApplication application, CancellationToken cancellationToken);
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the unique identifier associated with the application.
+        /// </returns>
+        Task<string> CreateAsync(TApplication application, CancellationToken cancellationToken);
 
         /// <summary>
         /// Retrieves an application using its unique identifier.
         /// </summary>
         /// <param name="identifier">The unique identifier associated with the application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the client application corresponding to the identifier.
+        /// </returns>
         Task<TApplication> FindByIdAsync(string identifier, CancellationToken cancellationToken);
 
         /// <summary>
@@ -34,7 +40,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="url">The post_logout_redirect_uri associated with the application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation, whose result
+        /// returns the client application corresponding to the post_logout_redirect_uri.
+        /// </returns>
         Task<TApplication> FindByLogoutRedirectUri(string url, CancellationToken cancellationToken);
 
         /// <summary>
@@ -42,7 +51,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the client type of the application (by default, "public").
+        /// </returns>
         Task<string> GetClientTypeAsync(TApplication application, CancellationToken cancellationToken);
 
         /// <summary>
@@ -50,7 +62,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the display name associated with the application.
+        /// </returns>
         Task<string> GetDisplayNameAsync(TApplication application, CancellationToken cancellationToken);
 
         /// <summary>
@@ -58,7 +73,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the redirect_uri associated with the application.
+        /// </returns>
         Task<string> GetRedirectUriAsync(TApplication application, CancellationToken cancellationToken);
 
         /// <summary>
@@ -66,7 +84,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the hashed secret associated with the application.
+        /// </returns>
         Task<string> GetHashedSecretAsync(TApplication application, CancellationToken cancellationToken);
     }
 }

src/OpenIddict.Core/Stores/IOpenIddictTokenStore.cs

@@ -16,18 +16,23 @@ namespace OpenIddict {
         /// <summary>
         /// Creates a new token, defined by a unique identifier and a token type.
         /// </summary>
-        /// <param name="identifier">The unique identifier associated with the token to create.</param>
         /// <param name="type">The token type.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
-        Task CreateAsync(string identifier, string type, CancellationToken cancellationToken);
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the unique identifier associated with the token.
+        /// </returns>
+        Task<string> CreateAsync(string type, CancellationToken cancellationToken);
 
         /// <summary>
         /// Retrieves an token using its unique identifier.
         /// </summary>
         /// <param name="identifier">The unique identifier associated with the token.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the token corresponding to the unique identifier.
+        /// </returns>
         Task<TToken> FindByIdAsync(string identifier, CancellationToken cancellationToken);
 
         /// <summary>

src/OpenIddict.EntityFramework/Models/OpenIddictApplication.cs

@@ -55,6 +55,6 @@ namespace OpenIddict {
         /// Gets or sets the application type
         /// associated with the current application.
         /// </summary>
-        public virtual string Type { get; set; }
+        public virtual string Type { get; set; } = OpenIddictConstants.ClientTypes.Public;
     }
 }

src/OpenIddict.EntityFramework/Stores/OpenIddictApplicationStore.cs

@@ -41,14 +41,22 @@ namespace OpenIddict {
         /// <param name="application">The application to create.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
         /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
-        public virtual Task CreateAsync(TApplication application, CancellationToken cancellationToken) {
+        public virtual async Task<string> CreateAsync(TApplication application, CancellationToken cancellationToken) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
             }
 
+            // Ensure that the key type can be serialized.
+            var converter = TypeDescriptor.GetConverter(typeof(TKey));
+            if (!converter.CanConvertTo(typeof(string))) {
+                throw new InvalidOperationException($"The '{typeof(TKey).Name}' key type is not supported.");
+            }
+
             Context.Add(application);
 
-            return Context.SaveChangesAsync(cancellationToken);
+            await Context.SaveChangesAsync(cancellationToken);
+
+            return converter.ConvertToInvariantString(application.Id);
         }
 
         /// <summary>
@@ -56,7 +64,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="identifier">The unique identifier associated with the application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the client application corresponding to the identifier.
+        /// </returns>
         public virtual Task<TApplication> FindByIdAsync(string identifier, CancellationToken cancellationToken) {
             var converter = TypeDescriptor.GetConverter(typeof(TKey));
 
@@ -76,7 +87,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="url">The post_logout_redirect_uri associated with the application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation, whose result
+        /// returns the client application corresponding to the post_logout_redirect_uri.
+        /// </returns>
         public virtual Task<TApplication> FindByLogoutRedirectUri(string url, CancellationToken cancellationToken) {
             return Applications.SingleOrDefaultAsync(application => application.LogoutRedirectUri == url, cancellationToken);
         }
@@ -86,7 +100,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the client type of the application (by default, "public").
+        /// </returns>
         public virtual Task<string> GetClientTypeAsync(TApplication application, CancellationToken cancellationToken) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
@@ -100,7 +117,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the display name associated with the application.
+        /// </returns>
         public virtual Task<string> GetDisplayNameAsync(TApplication application, CancellationToken cancellationToken) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
@@ -114,7 +134,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the redirect_uri associated with the application.
+        /// </returns>
         public virtual Task<string> GetRedirectUriAsync(TApplication application, CancellationToken cancellationToken) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));
@@ -128,7 +151,10 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="application">The application.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the hashed secret associated with the application.
+        /// </returns>
         public virtual Task<string> GetHashedSecretAsync(TApplication application, CancellationToken cancellationToken) {
             if (application == null) {
                 throw new ArgumentNullException(nameof(application));

src/OpenIddict.EntityFramework/Stores/OpenIddictTokenStore.cs

@@ -38,24 +38,25 @@ namespace OpenIddict {
         /// <summary>
         /// Creates a new token, defined by a unique identifier and a token type.
         /// </summary>
-        /// <param name="identifier">The unique identifier associated with the token to create.</param>
         /// <param name="type">The token type.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
-        public virtual Task CreateAsync(string identifier, string type, CancellationToken cancellationToken) {
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the unique identifier associated with the token.
+        /// </returns>
+        public virtual async Task<string> CreateAsync(string type, CancellationToken cancellationToken) {
+            // Ensure that the key type can be serialized.
             var converter = TypeDescriptor.GetConverter(typeof(TKey));
-
+            if (!converter.CanConvertTo(typeof(string))) {
-            // Ensure that the key type is compatible with string keys.
+                throw new InvalidOperationException($"The '{typeof(TKey).Name}' key type is not supported.");
-            if (!converter.CanConvertFrom(typeof(string))) {
-                return Task.FromResult(0);
             }
 
-            var key = (TKey) converter.ConvertFromInvariantString(identifier);
+            var token = new TToken { Type = type };
-
-            var token = new TToken { Id = key, Type = type };
             Tokens.Add(token);
 
-            return Context.SaveChangesAsync(cancellationToken);
+            await Context.SaveChangesAsync(cancellationToken);
+
+            return converter.ConvertToInvariantString(token.Id);
         }
 
         /// <summary>
@@ -63,12 +64,14 @@ namespace OpenIddict {
         /// </summary>
         /// <param name="identifier">The unique identifier associated with the token.</param>
         /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-        /// <returns>A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation,
+        /// whose result returns the token corresponding to the unique identifier.
+        /// </returns>
         public virtual Task<TToken> FindByIdAsync(string identifier, CancellationToken cancellationToken) {
-            var converter = TypeDescriptor.GetConverter(typeof(TKey));
-
             // If the string key cannot be converted to TKey, return null
             // to indicate that the requested token doesn't exist.
+            var converter = TypeDescriptor.GetConverter(typeof(TKey));
             if (!converter.CanConvertFrom(typeof(string))) {
                 return Task.FromResult<TToken>(null);
             }