From 80bfa33b3645568f958c0a3fc20eed66d6b2d3ed Mon Sep 17 00:00:00 2001
From: Vladyslav Martynets <Amialc@users.noreply.github.com>
Date: Mon, 16 Jul 2018 13:20:19 +0300
Subject: [PATCH] Replace new() constraints by Activator.CreateInstance() to
 allow using abstract entities as generic parameters

---
 .../OpenIddictEntityFrameworkBuilder.cs       |  8 +++----
 .../OpenIddictEntityFrameworkExtensions.cs    |  8 +++----
 .../Stores/OpenIddictApplicationStore.cs      | 23 +++++++++++++++----
 .../Stores/OpenIddictAuthorizationStore.cs    | 23 +++++++++++++++----
 .../Stores/OpenIddictScopeStore.cs            | 19 +++++++++++++--
 .../Stores/OpenIddictTokenStore.cs            | 23 +++++++++++++++----
 .../OpenIddictEntityFrameworkCoreBuilder.cs   |  8 +++----
 ...OpenIddictEntityFrameworkCoreCustomizer.cs |  8 +++----
 ...OpenIddictEntityFrameworkCoreExtensions.cs | 16 ++++++-------
 .../Stores/OpenIddictApplicationStore.cs      | 23 +++++++++++++++----
 .../Stores/OpenIddictAuthorizationStore.cs    | 23 +++++++++++++++----
 .../Stores/OpenIddictScopeStore.cs            | 19 +++++++++++++--
 .../Stores/OpenIddictTokenStore.cs            | 23 +++++++++++++++----
 .../OpenIddictMongoDbBuilder.cs               |  8 +++----
 .../Stores/OpenIddictApplicationStore.cs      | 19 +++++++++++++--
 .../Stores/OpenIddictAuthorizationStore.cs    | 19 +++++++++++++--
 .../Stores/OpenIddictScopeStore.cs            | 19 +++++++++++++--
 .../Stores/OpenIddictTokenStore.cs            | 19 +++++++++++++--
 18 files changed, 244 insertions(+), 64 deletions(-)

diff --git a/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkBuilder.cs b/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkBuilder.cs
index c3a99690..363231c3 100644
--- a/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkBuilder.cs
+++ b/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkBuilder.cs
@@ -94,10 +94,10 @@ namespace Microsoft.Extensions.DependencyInjection
         /// </summary>
         /// <returns>The <see cref="OpenIddictEntityFrameworkBuilder"/>.</returns>
         public OpenIddictEntityFrameworkBuilder ReplaceDefaultEntities<TApplication, TAuthorization, TScope, TToken, TKey>()
-            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-            where TScope : OpenIddictScope<TKey>, new()
-            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+            where TScope : OpenIddictScope<TKey>
+            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
             Services.Configure<OpenIddictCoreOptions>(options =>
diff --git a/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkExtensions.cs b/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkExtensions.cs
index f1f63302..c1157418 100644
--- a/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkExtensions.cs
+++ b/src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkExtensions.cs
@@ -98,10 +98,10 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <param name="builder">The builder used to configure the Entity Framework context.</param>
         /// <returns>The Entity Framework context builder.</returns>
         public static DbModelBuilder UseOpenIddict<TApplication, TAuthorization, TScope, TToken, TKey>([NotNull] this DbModelBuilder builder)
-            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-            where TScope : OpenIddictScope<TKey>, new()
-            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+            where TScope : OpenIddictScope<TKey>
+            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
             if (builder == null)
diff --git a/src/OpenIddict.EntityFramework/Stores/OpenIddictApplicationStore.cs b/src/OpenIddict.EntityFramework/Stores/OpenIddictApplicationStore.cs
index 4b59dc15..a2cdacc5 100644
--- a/src/OpenIddict.EntityFramework/Stores/OpenIddictApplicationStore.cs
+++ b/src/OpenIddict.EntityFramework/Stores/OpenIddictApplicationStore.cs
@@ -52,9 +52,9 @@ namespace OpenIddict.EntityFramework
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictApplicationStore<TApplication, TAuthorization, TToken, TContext, TKey> : IOpenIddictApplicationStore<TApplication>
-        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -651,7 +651,22 @@ namespace OpenIddict.EntityFramework
         /// whose result returns the instantiated application, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TApplication> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TApplication>(new TApplication());
+        {
+            try
+            {
+                return new ValueTask<TApplication>(Activator.CreateInstance<TApplication>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TApplication>(Task.FromException<TApplication>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new application instance.")
+                        .Append("Make sure that the application entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom application store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.EntityFramework/Stores/OpenIddictAuthorizationStore.cs b/src/OpenIddict.EntityFramework/Stores/OpenIddictAuthorizationStore.cs
index 0c9f0814..11723500 100644
--- a/src/OpenIddict.EntityFramework/Stores/OpenIddictAuthorizationStore.cs
+++ b/src/OpenIddict.EntityFramework/Stores/OpenIddictAuthorizationStore.cs
@@ -52,9 +52,9 @@ namespace OpenIddict.EntityFramework
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictAuthorizationStore<TAuthorization, TApplication, TToken, TContext, TKey> : IOpenIddictAuthorizationStore<TAuthorization>
-        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -574,7 +574,22 @@ namespace OpenIddict.EntityFramework
         /// whose result returns the instantiated authorization, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TAuthorization> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TAuthorization>(new TAuthorization());
+        {
+            try
+            {
+                return new ValueTask<TAuthorization>(Activator.CreateInstance<TAuthorization>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TAuthorization>(Task.FromException<TAuthorization>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new authorization instance.")
+                        .Append("Make sure that the authorization entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom authorization store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.EntityFramework/Stores/OpenIddictScopeStore.cs b/src/OpenIddict.EntityFramework/Stores/OpenIddictScopeStore.cs
index c3e702c5..34bed152 100644
--- a/src/OpenIddict.EntityFramework/Stores/OpenIddictScopeStore.cs
+++ b/src/OpenIddict.EntityFramework/Stores/OpenIddictScopeStore.cs
@@ -46,7 +46,7 @@ namespace OpenIddict.EntityFramework
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictScopeStore<TScope, TContext, TKey> : IOpenIddictScopeStore<TScope>
-        where TScope : OpenIddictScope<TKey>, new()
+        where TScope : OpenIddictScope<TKey>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -439,7 +439,22 @@ namespace OpenIddict.EntityFramework
         /// whose result returns the instantiated scope, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TScope> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TScope>(new TScope());
+        {
+            try
+            {
+                return new ValueTask<TScope>(Activator.CreateInstance<TScope>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TScope>(Task.FromException<TScope>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new scope instance.")
+                        .Append("Make sure that the scope entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom scope store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.EntityFramework/Stores/OpenIddictTokenStore.cs b/src/OpenIddict.EntityFramework/Stores/OpenIddictTokenStore.cs
index e3855376..11ae518c 100644
--- a/src/OpenIddict.EntityFramework/Stores/OpenIddictTokenStore.cs
+++ b/src/OpenIddict.EntityFramework/Stores/OpenIddictTokenStore.cs
@@ -52,9 +52,9 @@ namespace OpenIddict.EntityFramework
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictTokenStore<TToken, TApplication, TAuthorization, TContext, TKey> : IOpenIddictTokenStore<TToken>
-        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
-        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
+        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
+        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -582,7 +582,22 @@ namespace OpenIddict.EntityFramework
         /// whose result returns the instantiated token, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TToken> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TToken>(new TToken());
+        {
+            try
+            {
+                return new ValueTask<TToken>(Activator.CreateInstance<TToken>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TToken>(Task.FromException<TToken>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new token instance.")
+                        .Append("Make sure that the token entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom token store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreBuilder.cs b/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreBuilder.cs
index 5bd9ff63..051e0ef8 100644
--- a/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreBuilder.cs
+++ b/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreBuilder.cs
@@ -103,10 +103,10 @@ namespace Microsoft.Extensions.DependencyInjection
         /// </summary>
         /// <returns>The <see cref="OpenIddictEntityFrameworkCoreBuilder"/>.</returns>
         public OpenIddictEntityFrameworkCoreBuilder ReplaceDefaultEntities<TApplication, TAuthorization, TScope, TToken, TKey>()
-            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-            where TScope : OpenIddictScope<TKey>, new()
-            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+            where TScope : OpenIddictScope<TKey>
+            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
             Services.Configure<OpenIddictCoreOptions>(options =>
diff --git a/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreCustomizer.cs b/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreCustomizer.cs
index bcbceab6..e254dac5 100644
--- a/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreCustomizer.cs
+++ b/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreCustomizer.cs
@@ -18,10 +18,10 @@ namespace OpenIddict.EntityFrameworkCore
     /// required by the OpenIddict stack in an Entity Framework context.
     /// </summary>
     public class OpenIddictEntityFrameworkCoreCustomizer<TApplication, TAuthorization, TScope, TToken, TKey> : RelationalModelCustomizer
-        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-        where TScope : OpenIddictScope<TKey>, new()
-        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+        where TScope : OpenIddictScope<TKey>
+        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
         where TKey : IEquatable<TKey>
     {
         public OpenIddictEntityFrameworkCoreCustomizer([NotNull] ModelCustomizerDependencies dependencies)
diff --git a/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreExtensions.cs b/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreExtensions.cs
index 7810b622..ecd86e09 100644
--- a/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreExtensions.cs
+++ b/src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreExtensions.cs
@@ -107,10 +107,10 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <param name="builder">The builder used to configure the Entity Framework context.</param>
         /// <returns>The Entity Framework context builder.</returns>
         public static DbContextOptionsBuilder UseOpenIddict<TApplication, TAuthorization, TScope, TToken, TKey>([NotNull] this DbContextOptionsBuilder builder)
-            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-            where TScope : OpenIddictScope<TKey>, new()
-            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+            where TScope : OpenIddictScope<TKey>
+            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
             if (builder == null)
@@ -153,10 +153,10 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <param name="builder">The builder used to configure the Entity Framework context.</param>
         /// <returns>The Entity Framework context builder.</returns>
         public static ModelBuilder UseOpenIddict<TApplication, TAuthorization, TScope, TToken, TKey>([NotNull] this ModelBuilder builder)
-            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-            where TScope : OpenIddictScope<TKey>, new()
-            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+            where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+            where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+            where TScope : OpenIddictScope<TKey>
+            where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
             if (builder == null)
diff --git a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictApplicationStore.cs b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictApplicationStore.cs
index a956a8d1..b6f40614 100644
--- a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictApplicationStore.cs
+++ b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictApplicationStore.cs
@@ -74,9 +74,9 @@ namespace OpenIddict.EntityFrameworkCore
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictApplicationStore<TApplication, TAuthorization, TToken, TContext, TKey> : IOpenIddictApplicationStore<TApplication>
-        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -718,7 +718,22 @@ namespace OpenIddict.EntityFrameworkCore
         /// whose result returns the instantiated application, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TApplication> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TApplication>(new TApplication());
+        {
+            try
+            {
+                return new ValueTask<TApplication>(Activator.CreateInstance<TApplication>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TApplication>(Task.FromException<TApplication>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new application instance.")
+                        .Append("Make sure that the application entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom application store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictAuthorizationStore.cs b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictAuthorizationStore.cs
index a10c67b5..2d9d826a 100644
--- a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictAuthorizationStore.cs
+++ b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictAuthorizationStore.cs
@@ -74,9 +74,9 @@ namespace OpenIddict.EntityFrameworkCore
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictAuthorizationStore<TAuthorization, TApplication, TToken, TContext, TKey> : IOpenIddictAuthorizationStore<TAuthorization>
-        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
-        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
+        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
+        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -662,7 +662,22 @@ namespace OpenIddict.EntityFrameworkCore
         /// whose result returns the instantiated authorization, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TAuthorization> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TAuthorization>(new TAuthorization());
+        {
+            try
+            {
+                return new ValueTask<TAuthorization>(Activator.CreateInstance<TAuthorization>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TAuthorization>(Task.FromException<TAuthorization>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new authorization instance.")
+                        .Append("Make sure that the authorization entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom authorization store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictScopeStore.cs b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictScopeStore.cs
index e18045d5..a8364dd7 100644
--- a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictScopeStore.cs
+++ b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictScopeStore.cs
@@ -64,7 +64,7 @@ namespace OpenIddict.EntityFrameworkCore
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictScopeStore<TScope, TContext, TKey> : IOpenIddictScopeStore<TScope>
-        where TScope : OpenIddictScope<TKey>, new()
+        where TScope : OpenIddictScope<TKey>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -480,7 +480,22 @@ namespace OpenIddict.EntityFrameworkCore
         /// whose result returns the instantiated scope, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TScope> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TScope>(new TScope());
+        {
+            try
+            {
+                return new ValueTask<TScope>(Activator.CreateInstance<TScope>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TScope>(Task.FromException<TScope>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new scope instance.")
+                        .Append("Make sure that the scope entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom scope store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictTokenStore.cs b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictTokenStore.cs
index e031e744..59c5590b 100644
--- a/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictTokenStore.cs
+++ b/src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictTokenStore.cs
@@ -74,9 +74,9 @@ namespace OpenIddict.EntityFrameworkCore
     /// <typeparam name="TContext">The type of the Entity Framework database context.</typeparam>
     /// <typeparam name="TKey">The type of the entity primary keys.</typeparam>
     public class OpenIddictTokenStore<TToken, TApplication, TAuthorization, TContext, TKey> : IOpenIddictTokenStore<TToken>
-        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>, new()
-        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>, new()
-        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>, new()
+        where TToken : OpenIddictToken<TKey, TApplication, TAuthorization>
+        where TApplication : OpenIddictApplication<TKey, TAuthorization, TToken>
+        where TAuthorization : OpenIddictAuthorization<TKey, TApplication, TToken>
         where TContext : DbContext
         where TKey : IEquatable<TKey>
     {
@@ -660,7 +660,22 @@ namespace OpenIddict.EntityFrameworkCore
         /// whose result returns the instantiated token, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TToken> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TToken>(new TToken());
+        {
+            try
+            {
+                return new ValueTask<TToken>(Activator.CreateInstance<TToken>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TToken>(Task.FromException<TToken>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new token instance.")
+                        .Append("Make sure that the token entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom token store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.MongoDb/OpenIddictMongoDbBuilder.cs b/src/OpenIddict.MongoDb/OpenIddictMongoDbBuilder.cs
index 7a6a41a6..a5834add 100644
--- a/src/OpenIddict.MongoDb/OpenIddictMongoDbBuilder.cs
+++ b/src/OpenIddict.MongoDb/OpenIddictMongoDbBuilder.cs
@@ -78,7 +78,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// </summary>
         /// <returns>The <see cref="OpenIddictMongoDbBuilder"/>.</returns>
         public OpenIddictMongoDbBuilder ReplaceDefaultApplicationEntity<TApplication>()
-            where TApplication : OpenIddictApplication, new()
+            where TApplication : OpenIddictApplication
         {
             Services.Configure<OpenIddictCoreOptions>(options => options.DefaultApplicationType = typeof(TApplication));
 
@@ -90,7 +90,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// </summary>
         /// <returns>The <see cref="OpenIddictMongoDbBuilder"/>.</returns>
         public OpenIddictMongoDbBuilder ReplaceDefaultAuthorizationEntity<TAuthorization>()
-            where TAuthorization : OpenIddictAuthorization, new()
+            where TAuthorization : OpenIddictAuthorization
         {
             Services.Configure<OpenIddictCoreOptions>(options => options.DefaultAuthorizationType = typeof(TAuthorization));
 
@@ -102,7 +102,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// </summary>
         /// <returns>The <see cref="OpenIddictMongoDbBuilder"/>.</returns>
         public OpenIddictMongoDbBuilder ReplaceDefaultScopeEntity<TScope>()
-            where TScope : OpenIddictScope, new()
+            where TScope : OpenIddictScope
         {
             Services.Configure<OpenIddictCoreOptions>(options => options.DefaultScopeType = typeof(TScope));
 
@@ -114,7 +114,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// </summary>
         /// <returns>The <see cref="OpenIddictMongoDbBuilder"/>.</returns>
         public OpenIddictMongoDbBuilder ReplaceDefaultTokenEntity<TToken>()
-            where TToken : OpenIddictToken, new()
+            where TToken : OpenIddictToken
         {
             Services.Configure<OpenIddictCoreOptions>(options => options.DefaultTokenType = typeof(TToken));
 
diff --git a/src/OpenIddict.MongoDb/Stores/OpenIddictApplicationStore.cs b/src/OpenIddict.MongoDb/Stores/OpenIddictApplicationStore.cs
index cbde5016..76cea3b6 100644
--- a/src/OpenIddict.MongoDb/Stores/OpenIddictApplicationStore.cs
+++ b/src/OpenIddict.MongoDb/Stores/OpenIddictApplicationStore.cs
@@ -28,7 +28,7 @@ namespace OpenIddict.MongoDb
     /// </summary>
     /// <typeparam name="TApplication">The type of the Application entity.</typeparam>
     public class OpenIddictApplicationStore<TApplication> : IOpenIddictApplicationStore<TApplication>
-        where TApplication : OpenIddictApplication, new()
+        where TApplication : OpenIddictApplication
     {
         public OpenIddictApplicationStore(
             [NotNull] IMemoryCache cache,
@@ -490,7 +490,22 @@ namespace OpenIddict.MongoDb
         /// whose result returns the instantiated application, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TApplication> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TApplication>(new TApplication());
+        {
+            try
+            {
+                return new ValueTask<TApplication>(Activator.CreateInstance<TApplication>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TApplication>(Task.FromException<TApplication>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new application instance.")
+                        .Append("Make sure that the application entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom application store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.MongoDb/Stores/OpenIddictAuthorizationStore.cs b/src/OpenIddict.MongoDb/Stores/OpenIddictAuthorizationStore.cs
index 537a97ad..cdb0002c 100644
--- a/src/OpenIddict.MongoDb/Stores/OpenIddictAuthorizationStore.cs
+++ b/src/OpenIddict.MongoDb/Stores/OpenIddictAuthorizationStore.cs
@@ -28,7 +28,7 @@ namespace OpenIddict.MongoDb
     /// </summary>
     /// <typeparam name="TAuthorization">The type of the Authorization entity.</typeparam>
     public class OpenIddictAuthorizationStore<TAuthorization> : IOpenIddictAuthorizationStore<TAuthorization>
-        where TAuthorization : OpenIddictAuthorization, new()
+        where TAuthorization : OpenIddictAuthorization
     {
         public OpenIddictAuthorizationStore(
             [NotNull] IMemoryCache cache,
@@ -489,7 +489,22 @@ namespace OpenIddict.MongoDb
         /// whose result returns the instantiated authorization, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TAuthorization> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TAuthorization>(new TAuthorization());
+        {
+            try
+            {
+                return new ValueTask<TAuthorization>(Activator.CreateInstance<TAuthorization>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TAuthorization>(Task.FromException<TAuthorization>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new authorization instance.")
+                        .Append("Make sure that the authorization entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom authorization store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.MongoDb/Stores/OpenIddictScopeStore.cs b/src/OpenIddict.MongoDb/Stores/OpenIddictScopeStore.cs
index 40646907..6f67aa56 100644
--- a/src/OpenIddict.MongoDb/Stores/OpenIddictScopeStore.cs
+++ b/src/OpenIddict.MongoDb/Stores/OpenIddictScopeStore.cs
@@ -28,7 +28,7 @@ namespace OpenIddict.MongoDb
     /// </summary>
     /// <typeparam name="TScope">The type of the Scope entity.</typeparam>
     public class OpenIddictScopeStore<TScope> : IOpenIddictScopeStore<TScope>
-        where TScope : OpenIddictScope, new()
+        where TScope : OpenIddictScope
     {
         public OpenIddictScopeStore(
             [NotNull] IMemoryCache cache,
@@ -394,7 +394,22 @@ namespace OpenIddict.MongoDb
         /// whose result returns the instantiated scope, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TScope> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TScope>(new TScope());
+        {
+            try
+            {
+                return new ValueTask<TScope>(Activator.CreateInstance<TScope>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TScope>(Task.FromException<TScope>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new scope instance.")
+                        .Append("Make sure that the scope entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom scope store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.
diff --git a/src/OpenIddict.MongoDb/Stores/OpenIddictTokenStore.cs b/src/OpenIddict.MongoDb/Stores/OpenIddictTokenStore.cs
index 0fbf9f4a..f41f0542 100644
--- a/src/OpenIddict.MongoDb/Stores/OpenIddictTokenStore.cs
+++ b/src/OpenIddict.MongoDb/Stores/OpenIddictTokenStore.cs
@@ -28,7 +28,7 @@ namespace OpenIddict.MongoDb
     /// </summary>
     /// <typeparam name="TToken">The type of the Token entity.</typeparam>
     public class OpenIddictTokenStore<TToken> : IOpenIddictTokenStore<TToken>
-        where TToken : OpenIddictToken, new()
+        where TToken : OpenIddictToken
     {
         public OpenIddictTokenStore(
             [NotNull] IMemoryCache cache,
@@ -507,7 +507,22 @@ namespace OpenIddict.MongoDb
         /// whose result returns the instantiated token, that can be persisted in the database.
         /// </returns>
         public virtual ValueTask<TToken> InstantiateAsync(CancellationToken cancellationToken)
-            => new ValueTask<TToken>(new TToken());
+        {
+            try
+            {
+                return new ValueTask<TToken>(Activator.CreateInstance<TToken>());
+            }
+
+            catch (MemberAccessException exception)
+            {
+                return new ValueTask<TToken>(Task.FromException<TToken>(
+                    new InvalidOperationException(new StringBuilder()
+                        .AppendLine("An error occurred while trying to create a new token instance.")
+                        .Append("Make sure that the token entity is not abstract and has a public parameterless constructor ")
+                        .Append("or create a custom token store that overrides 'InstantiateAsync()' to use a custom factory.")
+                        .ToString(), exception)));
+            }
+        }
 
         /// <summary>
         /// Executes the specified query and returns all the corresponding elements.