GraphQL.Client.Abstractions 6.1.0

GraphQL.Client

A GraphQL Client for .NET Standard over HTTP.

Provides the following packages:

Package	Downloads	Nuget Latest
GraphQL.Client
GraphQL.Client.Abstractions
GraphQL.Client.Abstractions.Websocket
GraphQL.Client.LocalExecution
GraphQL.Client.Serializer.Newtonsoft
GraphQL.Client.Serializer.SystemTextJson
GraphQL.Primitives

Specification

The Library will try to follow the following standards and documents:

• GraphQL Specification
• GraphQL HomePage

Usage

The intended use of GraphQLHttpClient is to keep one instance alive per endpoint (obvious in case you're operating full websocket, but also true for regular requests) and is built with thread-safety in mind.

Create a GraphQLHttpClient

// To use NewtonsoftJsonSerializer, add a reference to 
// NuGet package GraphQL.Client.Serializer.Newtonsoft
var graphQLClient = new GraphQLHttpClient(
    "https://api.example.com/graphql", 
    new NewtonsoftJsonSerializer());

[!NOTE] GraphQLHttpClient is meant to be used as a single long-lived instance per endpoint (i.e. register as singleton in a DI system), which should be reused for multiple requests.

Create a GraphQLRequest:

Simple Request:

var heroRequest = new GraphQLRequest {
    Query = """
    {
        hero {
            name
        }
    }
    """
};

OperationName and Variables Request:

var personAndFilmsRequest = new GraphQLRequest {
    Query ="""
    query PersonAndFilms($id: ID) {
        person(id: $id) {
            name
            filmConnection {
                films {
                    title
                }
            }
        }
    }
    """,
    OperationName = "PersonAndFilms",
    Variables = new {
        id = "cGVvcGxlOjE="
    }
};

[!WARNING] Be careful when using byte[] in your variables object, as most JSON serializers will treat that as binary data.

If you really need to send a list of bytes with a byte[] as a source, then convert it to a List<byte> first, which will tell the serializer to output a list of numbers instead of a base64-encoded string.

Execute Query/Mutation

public class ResponseType 
{
    public PersonType Person { get; set; }
}

public class PersonType 
{
    public string Name { get; set; }
    public FilmConnectionType FilmConnection { get; set; }    
}

public class FilmConnectionType {
    public List<FilmContentType> Films { get; set; }    
}

public class FilmContentType {
    public string Title { get; set; }
}

var graphQLResponse = await graphQLClient.SendQueryAsync<ResponseType>(personAndFilmsRequest);

var personName = graphQLResponse.Data.Person.Name;

Using the extension method for anonymously typed responses (namespace GraphQL.Client.Abstractions) you could achieve the same result with the following code:

var graphQLResponse = await graphQLClient.SendQueryAsync(
    personAndFilmsRequest, 
    () => new { person = new PersonType()});
var personName = graphQLResponse.Data.person.Name;

[!IMPORTANT] Note that the field in the GraphQL response which gets deserialized into the response object is the data field.

A common mistake is to try to directly use the PersonType class as response type (because thats the thing you actually want to query), but the returned response object contains a property person containing a PersonType object (like the ResponseType modelled above).

Use Subscriptions

public class UserJoinedSubscriptionResult {
    public ChatUser UserJoined { get; set; }

    public class ChatUser {
        public string DisplayName { get; set; }
        public string Id { get; set; }
    }
}

Create subscription

var userJoinedRequest = new GraphQLRequest {
    Query = @"
    subscription {
        userJoined{
            displayName
            id
        }
    }"
};

IObservable<GraphQLResponse<UserJoinedSubscriptionResult>> subscriptionStream 
    = client.CreateSubscriptionStream<UserJoinedSubscriptionResult>(userJoinedRequest);

var subscription = subscriptionStream.Subscribe(response => 
    {
        Console.WriteLine($"user '{response.Data.UserJoined.DisplayName}' joined")
    });

End Subscription

subscription.Dispose();

Automatic persisted queries (APQ)

Automatic persisted queries (APQ) are supported since client version 6.1.0.

APQ can be enabled by configuring GraphQLHttpClientOptions.EnableAutomaticPersistedQueries to resolve to true.

By default, the client will automatically disable APQ for the current session if the server responds with a PersistedQueryNotSupported error or a 400 or 600 HTTP status code. This can be customized by configuring GraphQLHttpClientOptions.DisableAPQ.

To re-enable APQ after it has been automatically disabled, GraphQLHttpClient needs to be disposed an recreated.

APQ works by first sending a hash of the query string to the server, and only sending the full query string if the server has not yet cached a query with a matching hash. With queries supplied as a string parameter to GraphQLRequest, the hash gets computed each time the request is sent.

When you want to reuse a query string (propably to leverage APQ 😉), declare the query using the GraphQLQuery class. This way, the hash gets computed once on construction of the GraphQLQuery object and handed down to each GraphQLRequest using the query.

GraphQLQuery query = new("""
                         query PersonAndFilms($id: ID) {
                             person(id: $id) {
                                 name
                                 filmConnection {
                                     films {
                                         title
                                     }
                                 }
                             }
                         }
                         """);
                         
var graphQLResponse = await graphQLClient.SendQueryAsync<ResponseType>(
    query, 
    "PersonAndFilms",
    new { id = "cGVvcGxlOjE=" });

Syntax Highlighting for GraphQL strings in IDEs

.NET 7.0 introduced the StringSyntaxAttribute to have a unified way of telling what data is expected in a given string or ReadOnlySpan<char>. IDEs like Visual Studio and Rider can then use this to provide syntax highlighting and checking.

From v6.0.4 on all GraphQL string parameters in this library are decorated with the [StringSyntax("GraphQL")] attribute.

Currently, there is no native support for GraphQL formatting and syntax highlighting in Visual Studio, but the GraphQLTools Extension provides that for you.

For Rider, JetBrains provides a Plugin, too.

To leverage syntax highlighting in variable declarations, use the GraphQLQuery class.

Useful Links

• StarWars Example Server (GitHub)

• StarWars Example Server (EndPoint)

• GitHub GraphQL API Docs

• GitHub GraphQL Explorer

• GitHub GraphQL Endpoint

Blazor WebAssembly Limitations

Blazor WebAssembly differs from other platforms as it does not support all features of other .NET runtime implementations. For instance, the following WebSocket options properties are not supported and will not be set:

• ClientCertificates
• UseDefaultCredentials