EF Docs (#2634)

website/src/docs/docs.json

@@ -310,6 +310,16 @@
               }
             ]
           },
+          {
+            "path": "integrations",
+            "title": "Integrations",
+            "items": [
+              {
+                "path": "entity-framework",
+                "title": "Entity Framework"
+              }
+            ]
+          },
           {
             "path": "api-reference",
             "title": "API Reference",

website/src/docs/hotchocolate/integrations/entity-framework.md

@@ -0,0 +1,65 @@
+---
+title: Entity Framework
+---
+
+EF Core has seen huge adoption in the .NET world.  
+The execution engine of HotChocolate executes resolvers in parallel. This can lead to exceptions because
+the database context of Entity Framework cannot handle more than one request in parallel. 
+So if you are seeing exceptions like `A second operation started on this context before a previous operation completed.`
+or `Cannot access a disposed object...` the `HotChocolate.Data.EnityFramework` package has you back.
+It provides helpers that make EF integration with HotChocolate a breeze.
+
+The package was build on the foundation of EntityFramework Core v5.0.0.
+
+# Getting Started
+You first need to add the package reference to you project. You can do this with the `dotnet` cli:
+
+```
+  dotnet add package HotChocolate.Data.EntityFramework
+```
+
+The execution engine needs more than one database context. You should register the database context
+in a pool rather than transient. During execution database contexts are taken from this pool and returned
+once the resolver is completed. This has a smaller memory impact, as creating a new context for each resolver.
+
+```csharp
+services.AddPooledDbContextFactory<SomeDbContext>(b => b /*your configuration */)
+```
+
+> ⚠️ **Note:** The configuration of `AddPooledDbContextFactory` replaces the `OnConfiguring` method of the `DBContext`. 
+> You have to move the configuration to the factory method if you use `OnConfiguring`
+
+
+# Using the DBContext
+A resolver has to get a database context from the pool, execute the query and then return the context back to the
+pool. 
+If you annotate you field with `UseDbContext()` all of this is handeled for you
+
+**Code First**
+```csharp
+public class QueryType : ObjectType
+{
+    protected override void Configure(IObjectTypeDescriptor descriptor)
+    {
+        descriptor
+            .Field("users")
+            .UseDbContext<SomeDbContext>()
+            .Resolver((ctx, ct) =>
+                {
+                    return ctx.Service<SomeDbContext>().Users;
+                })
+    }
+}
+```
+
+**Pure Code First**
+```csharp
+public class Query
+{
+    [UseDbContext(typeof(SomeDbContext))]
+    public IQueryable<User> GetUsers([ScopedService] SomeDbContext someDbContext)
+    {
+        return someDbContext.Users;
+    }
+}
+```