This guide will walk you through the manual migration steps to update your Hot Chocolate GraphQL server to version 13.

Start by installing the latest 13.x.x version of all of the HotChocolate.* packages referenced by your project.

Breaking changes

Things that have been removed or had a change in behavior that may cause your code not to compile or lead to unexpected behavior at runtime if not addressed.

@authorize on types

If you previously annotated a type with @authorize, either directly in the schema or via [Authorize] or descriptor.Authorize(), the authorization rule was copied to each field of this type. This meant the authorization rule would be evaluated for each selected field beneath the annotated type in a request. This is inefficient, so we switched to evaluating the authorization rule once on the field that returns the "authorized" type instead.

Let's imagine you currently have the following GraphQL schema:

type Query {
  user: User
}

type User @authorize {
  field1: String
  field2: Int
}

This is how the authorization rule would be evaluated previously and now:

Before

{
  user {
    # The authorization rule is evaluated here since this field is beneath
    # the `User` type, which is annotated with @authorize
    field1
    # The authorization rule is evaluated here since this field is beneath
    # the `User` type, which is annotated with @authorize
    field2
  }
}

After

{
  # The authorization rule is now evaluated here since the `user` field
  # returns the `User` type, which is annotated with @authorize
  user {
    field1
    field2
  }
}

We observed a common pattern to put a '@authorize' directive on the root types and secure all their fields.

With the new default behavior of authorization, this would now fail since annotating the type will ensure that all fields returning instances of this type will be validated. Since there is no field returning the root types in most cases, these authorization rules will have no effect.

With the Authorization overhaul, we also introduced a way to more efficiently implement such a pattern by moving parts of the authorization into the validation.

type Query @authorize(apply: VALIDATION) {
  user: User
}

type User {
  field1: String
  field2: Int
}

The ‘apply‘ argument defines when an authorization rule is applied. In the above case, the validation ensures that the GraphQL request documents authorization rules are fulfilled. We do that by collecting all authorization directives with ‘apply‘ set to ‘Validation‘ and running them before we start the execution.

RegisterDbContext

We changed the default DbContextKind from DbContextKind.Synchronized to DbContextKind.Resolver. If the instance of your DbContext doesn't need to be the same for each executed resolver during a request, this should lead to a performance improvement.

To restore the v12 default behavior, pass the DbContextKind.Synchronized to the RegisterDbContext<T> call.

Before

services.AddGraphQLServer()
    .RegisterDbContext<DbContext>()

After

services.AddGraphQLServer()
    .RegisterDbContext<DbContext>(DbContextKind.Synchronized)

Note: Only add this if your application requires it. You're better off with the new default otherwise.

Batching

As an added security measure, batching has been disabled per default in this release. If you require batching, you now need to explicitly enable it.

app.MapGraphQL().WithOptions(new GraphQLServerOptions
{
    EnableBatching = true
});

Previously you might have also configured the (now replaced) IHttpResultSerializer to produce a JsonArray for your batches:

services.AddHttpResultSerializer(batchSerialization: HttpResultSerialization.JsonArray)

This option has been removed in this release and batch results are now always being delivered through multipart/mixed responses. This allows us to send the batch results back to the client as soon as they are ready, without having to hold on to the result and performing a JSON array aggregation on the server. If you need an aggregated batch result, you should do the aggregation on the client instead.

Learn more about the batching

Nodes batch size

The number of nodes that can be requested through the nodes field is limited to 10 by default. See Nodes batch size for the details.

You can change this default to suite the needs of your application as shown below:

builder.Services.AddGraphQLServer()
    .ModifyOptions(o => o.MaxAllowedNodeBatchSize = 1);

UseOffsetPaging

In this release we aligned the naming of types generated by UseOffsetPaging with the behavior of UsePaging.

[UseOffsetPaging]
public IQueryable<Order> GetUserOrders() => ...

The above resolver would previously generated a schema like this:

type Query {
  userOrders(skip: Int, take: Int): OrderCollectionSegment
}

type OrderCollectionSegment {
  items: [Order!]
  pageInfo: CollectionSegmentInfo!
}

Notice how the CollectionSegment is named after the type being returned and not the name of the field. If you were to create a second resolver returning the same type also annotated with UseOffsetPaging, the previous CollectionSegment would be re-used. This could lead to issues, if you wanted to add additional information to only one of the CollectionSegments.

Given the same resolver from above, we now generate the following schema in v13, where the CollectionSegment is named after the field it's being returned from and not the field's return type:

type Query {
  userOrders(skip: Int, take: Int): UserOrdersCollectionSegment
}

type UserOrdersCollectionSegment {
  items: [Order!]
  pageInfo: CollectionSegmentInfo!
}

If you want to retain the old behavior, you can disable the inferring from the field name either on a per-field basis

[UseOffsetPaging(InferCollectionSegmentNameFromField = false)]

or change the global default

builder.Services
    .AddGraphQLServer()
    .SetPagingOptions(new PagingOptions
    {
        InferCollectionSegmentNameFromField = false
    });

Field naming

Previously only the first character in a property or method name was lowercased in the schema. This worked fine in most cases, but if a name started with multiple uppercase characters or was all uppercase, the resulting field name was pretty weird. In this release we therefore changed how those field names are being inferred.

Before

FooBar --> fooBar
IPAddress --> iPAddress
PLZ --> pLZ

After

FooBar --> fooBar
IPAddress --> ipAddress
PLZ --> plz

If you need to retain the old naming behavior or the inferred field name doesn't match your expectation, you can still explicitly override the name of the fields in question.

IHttpResultSerializer

In this release we have replaced the IHttpResultSerializer, and consequently the DefaultHttpResultSerializer, with the IHttpResponseFormatter and DefaultHttpResponseFormatter.

Below you can see how you can port your custom HTTP status code generation logic to the new contract:

Before

builder.Services.AddHttpResultSerializer<CustomHttpResultSerializer>();

// ...

public class CustomHttpResultSerializer : DefaultHttpResultSerializer
{
    public override HttpStatusCode GetStatusCode(IExecutionResult result)
    {
        if (result is IQueryResult queryResult &&
            queryResult.Errors?.Count > 0 &&
            queryResult.Errors.Any(error => error.Code == "SOME_AUTH_ISSUE"))
        {
            return HttpStatusCode.Forbidden;
        }

        return base.GetStatusCode(result);
    }
}

After

builder.Services.AddHttpResponseFormatter<CustomHttpResponseFormatter>();

// ...

public class CustomHttpResponseFormatter : DefaultHttpResponseFormatter
{
    protected override HttpStatusCode OnDetermineStatusCode(
        IQueryResult result, FormatInfo format,
        HttpStatusCode? proposedStatusCode)
    {
        if (result.Errors?.Count > 0 &&
            result.Errors.Any(error => error.Code == "SOME_AUTH_ISSUE"))
        {
            return HttpStatusCode.Forbidden;
        }

        return base.OnDetermineStatusCode(result, format, proposedStatusCode);
    }
}

HTTP transport

With this release we adopted the latest GraphQL over HTTP specification changes.

Most notably the server now returns the Content-Type: application/graphql-response+json;charset=utf-8 response header for requests without an Accept: application/json request header. This might break expectations of existing clients. Apollo Federation Gateway (@apollo/gateway) for example still expects responses from subgraphs to contain the Content-Type: application/json header.

If you need to support legacy clients that do not yet support the GraphQL over HTTP specification, you can

1. Send the Accept: application/json header in requests from the legacy client
2. Infer application/json as the Accept header value for requests with a missing Accept header or Accept: */*, by setting the HttpTransportVersion to Legacy:

builder.Services.AddHttpResponseFormatter(new HttpResponseFormatterOptions {
    HttpTransportVersion = HttpTransportVersion.Legacy
});

An Accept header with the value application/json will opt you out of the GraphQL over HTTP specification. The response Content-Type will now be application/json and a status code of 200 will be returned for every request, even if it had validation errors or a valid response could not be produced.

Learn more about the HTTP transport

DataLoaderAttribute

Previously you might have annotated DataLoaders in your resolver method signature with the [DataLoader] attribute. This attribute has been removed in v13 and can be safely removed from your code.

Before

public async Task<User> GetUserByIdAsync(string id, [DataLoader] UserDataLoader loader)
    => await loader.LoadAsync(id);

After

public async Task<User> GetUserByIdAsync(string id, UserDataLoader loader)
    => await loader.LoadAsync(id);

ITopicEventReceiver / ITopicEventSender

Previously you could use any type as the topic for an event stream. In this release we are requiring the topic to be a string.

Before

ITopicEventReceiver.SubscribeAsync<TTopic, TMessage>(TTopic topic,
    CancellationToken cancellationToken);

ITopicEventSender.SendAsync<TTopic, TMessage>(TTopic topic, TMessage message,
    CancellationToken cancellationToken)

After

ITopicEventReceiver.SubscribeAsync<TMessage>(string topicName,
    CancellationToken cancellationToken);

ITopicEventSender.SendAsync<TMessage>(string topicName, TMessage message,
    CancellationToken cancellationToken)

TopicAttribute

Previously you might have annotated the [Topic] attribute on a method argument, to designate its runtime value as a dynamic topic. Now we no longer allow the attribute on arguments, but only on the method itself.

Before

public class Subscription
{
    [Subscribe]
    public Book BookPublished([Topic] string author, [EventMessage] Book book)
        => book;
}

After

public class Subscription
{
    [Subscribe]
    // What's in between the curly braces must match an argument name.
    [Topic("{author}")]
    public Book BookPublished(string author, [EventMessage] Book book)
        => book;
}

AddInMemorySubscriptions / AddRedisSubscriptions

We moved the extension methods from the IServiceCollection to our IRequestExecutorBuilder.

Before

builder.Services.AddInMemorySubscriptions();
// or
builder.Services.AddRedisSubscriptions();

After

builder.Services
    .AddGraphQLServer()
    .AddInMemorySubscriptions()
    // or
    .AddRedisSubscriptions();

@defer / @stream

@defer and @stream have now been disabled per default. If you want to continue using them, you have to opt-in now:

services.AddGraphQLServer()
    .ModifyOptions(o =>
    {
        o.EnableDefer = true;
        o.EnableStream = true;
    });

If your client is setting an Accept header value that doesn't include multipart/mixed or text/event-stream, the server will no longer produce a response, because the client is signaling that it can't handle a streamed response. In order for the server to produce a streamed response, you now need to either

1. Omit the Accept header
2. Send an Accept header with the value */*, signaling that your client can handle any format
3. Send an Accept header which includes multipart/mixed and/or text/event-stream

There have also been changes to the response format of streamed responses. You can checkout the currently proposed format here.

NameString

In this release we have abandoned the NameString in favor of simple strings. Most commonly you would encounter the NameString when defining names for fields or types. Since string was already implicitly converted to NameString, there shouldn't be any issues unless you were instantiating a NameString yourself.

IResolverContext / IMiddlewareContext

Previously you could access properties like Document and RootType directly on the IResolverContext or the IMiddlewareContext. In this release we have moved these properties and they can now be accessed through the Operation property on the contexts. We have also removed the deprecated properties Field and FieldSelection.

context.Document --> context.Operation.Document context.RootType --> context.Operation.RootType context.Field --> context.Selection.Field context.FieldSelection --> context.Selection.SyntaxNode

Deprecations

Things that will continue to function this release, but we encourage you to move away from.

ScopedServiceAttribute

In this release, we are deprecating the [ScopedService] attribute and encourage you to use RegisterDbContext<T>(DbContextKind.Pooled) instead.

Checkout this part of our Entity Framework documentation to learn how to register your DbContext with DbContextKind.Pooled.

Afterward you just need to update your resolvers:

Before

[UseDbContext]
public IQueryable<User> GetUsers([ScopedService] MyDbContext dbContext)
    => dbContext.Users;

After

public IQueryable<User> GetUsers(MyDbContext dbContext)
    => dbContext.Users;

If you've been using [ScopedService] without a pooled DbContext, you can recreate its behavior by switching it out for [LocalState("FullName")] (where FullName is the full name of the method argument type).

SubscribeAndResolve

Before

public class Subscription
{
    [SubscribeAndResolve]
    public ValueTask<ISourceStream<Book>> BookPublished(string author,
        [Service] ITopicEventReceiver receiver)
    {
        var topic = $"{author}_PublishedBook";

        return receiver.SubscribeAsync<string, Book>(topic);
    }
}

After

public class Subscription
{
    public ValueTask<ISourceStream<Book>> SubscribeToPublishedBooks(
        string author, ITopicEventReceiver receiver)
    {
        var topic = $"{author}_PublishedBook";

        return receiver.SubscribeAsync<Book>(topic);
    }

    [Subscribe(With = nameof(SubscribeToPublishedBooks))]
    public Book BookPublished(string author, [EventMessage] Book book)
        => book;
}

LocalValue / ScopedValue / GlobalValue

We aligned the naming of state related APIs:

IResolverContext

• IResolverContext.GetGlobalValue --> IResolverContext.GetGlobalStateOrDefault
• IResolverContext.GetOrAddGlobalValue --> IResolverContext.GetOrSetGlobalState
• IResolverContext.SetGlobalValue --> IResolverContext.SetGlobalState
• IResolverContext.RemoveGlobalValue --> Removed
• IResolverContext.GetScopedValue --> IResolverContext.GetScopedStateOrDefault
• IResolverContext.GetOrAddScopedValue --> IResolverContext.GetOrSetScopedState
• IResolverContext.SetScopedValue --> IResolverContext.SetScopedState
• IResolverContext.RemoveScopedValue --> IResolverContext.RemoveScopedState
• IResolverContext.GetLocalValue --> IResolverContext.GetLocalStateOrDefault
• IResolverContext.GetOrAddLocalValue --> IResolverContext.GetOrSetLocalState
• IResolverContext.SetLocalValue --> IResolverContext.SetLocalState
• IResolverContext.RemoveLocalValue --> IResolverContext.RemoveLocalState

IQueryRequestBuilder

• IQueryRequestBuilder.SetProperties --> IQueryRequestBuilder.InitializeGlobalState
• IQueryRequestBuilder.SetProperty --> IQueryRequestBuilder.SetGlobalState
• IQueryRequestBuilder.AddProperty --> IQueryRequestBuilder.AddGlobalState
• IQueryRequestBuilder.TryAddProperty --> IQueryRequestBuilder.TryAddGlobalState
• IQueryRequestBuilder.TryRemoveProperty --> IQueryRequestBuilder.RemoveGlobalState