Add documentation for the Entity Framework 6.x integration

integrations/entity-framework.md

@@ -0,0 +1,103 @@
+# Entity Framework 6.x integration
+
+## Basic configuration
+
+To configure OpenIddict to use Entity Framework 6.x as the database for applications, authorizations, scopes and tokens, you'll need to:
+  - **Reference the `OpenIddict.EntityFramework` package**:
+
+    ```xml
+    <PackageReference Include="OpenIddict.EntityFramework" Version="3.1.1" />
+    ```
+
+  - **Create a database context deriving from `DbContext` and register the OpenIddict entities in the model**:
+
+    ```csharp
+    public class ApplicationDbContext : DbContext
+    {
+        protected override void OnModelCreating(DbModelBuilder modelBuilder)
+        {
+            base.OnModelCreating(modelBuilder);
+
+            modelBuilder.UseOpenIddict();
+        }
+    }
+    ```
+
+  - **Configure OpenIddict to use the Entity Framework 6.x stores**:
+
+    ```csharp
+    services.AddOpenIddict()
+        .AddCore(options =>
+        {
+            options.UseEntityFramework()
+                   .UseDbContext<ApplicationDbContext>();
+        });
+    ```
+
+  - **Use migrations or recreate the database to add the OpenIddict entities**.
+For more information, read [Code First Migrations](https://docs.microsoft.com/en-us/ef/ef6/modeling/code-first/migrations/).
+
+## Advanced configuration
+
+### Use a custom primary key type
+
+By default, the Entity Framework 6.x integration uses `string` primary keys, which matches the default key type used by ASP.NET Identity.
+
+> [!WARNING]
+> Unlike Entity Framework Core, Entity Framework 6.x doesn't support closed generic types, which prevents using the OpenIddict entities
+> without subclassing them. As such, using a custom primary key type is a bit more complicated with Entity Framework 6.x than with
+> Entity Framework Core and requires implementing custom entities, as highlighted in the next section.
+
+### Use custom entities
+
+For applications that require storing additional data alongside the properties used by OpenIddict, custom entities can be used. For that, you need to:
+  - **Create custom entities**:
+
+    ```csharp
+    public class CustomApplication : OpenIddictEntityFrameworkApplication<long, CustomAuthorization, CustomToken>
+    {
+        public string CustomProperty { get; set; }
+    }
+
+    public class CustomAuthorization : OpenIddictEntityFrameworkAuthorization<long, CustomApplication, CustomToken>
+    {
+        public string CustomProperty { get; set; }
+    }
+
+    public class CustomScope : OpenIddictEntityFrameworkScope<long>
+    {
+        public string CustomProperty { get; set; }
+    }
+
+    public class CustomToken : OpenIddictEntityFrameworkToken<long, CustomApplication, CustomAuthorization>
+    {
+        public string CustomProperty { get; set; }
+    }
+    ```
+
+  - **Call the generic `ReplaceDefaultEntities<TApplication, TAuthorization, TScope, TToken, TKey>()` method to force OpenIddict to use the custom entities**:
+
+    ```csharp
+    services.AddOpenIddict()
+        .AddCore(options =>
+        {
+            // Configure OpenIddict to use the custom entities.
+            options.UseEntityFramework()
+                   .UseDbContext<ApplicationDbContext>()
+                   .ReplaceDefaultEntities<CustomApplication, CustomAuthorization, CustomScope, CustomToken, long>();
+        });
+    ```
+
+  - **Register the custom entities in the model**:
+
+    ```csharp
+    public class ApplicationDbContext : DbContext
+    {
+        protected override void OnModelCreating(DbModelBuilder modelBuilder)
+        {
+            base.OnModelCreating(modelBuilder);
+
+            modelBuilder.UseOpenIddict<CustomApplication, CustomAuthorization, CustomScope, CustomToken, long>();
+        }
+    }
+    ```

integrations/toc.yml

@@ -1,6 +1,9 @@
 - name: Introduction
   href: index.md
 
+- name: Entity Framework
+  href: entity-framework.md
+
 - name: Entity Framework Core
   href: entity-framework-core.md