A collection of classes, tools, and utilities for creating Relay.js compatible GraphQL servers in dotnet.
Provides the following packages:
| Package | Downloads | NuGet Latest |
|---|---|---|
| GraphQL.Relay |  |
 |
Add the Nuget package:
$> dotnet add package GraphQL.RelayEnsure your resolver for GraphQL can resolve:
ConnectionType<>EdgeType<>NodeInterfacePageInfoType
If you're using the resolver from MVC (IServiceProvider), that might look like this:
services.AddTransient(typeof(ConnectionType<>));
services.AddTransient(typeof(EdgeType<>));
services.AddTransient<NodeInterface>();
services.AddTransient<PageInfoType>();Included are a few GraphQL types and helpers for creating Connections, Mutations, and Nodes
A top level Schema query type, which defines the required node root query;
public class StarWarsQuery : QueryGraphType
{
public StarWarsQuery() {
Field<DroidType>(
"hero",
resolve: context => new Droid { DroidId = "1", Name = "R2-D2" }
);
}
}
public class StarWarsSchema : Schema
{
public StarWarsSchema() {
Query = new StarWarsQuery();
}
}NodeTypes, are ObjectGraphTypes that implement the NodeInterface
and provide a GetById method, which allows Relay (via the node() Query) to refetch nodes when it needs to.
Nodes, also provide a convenient Id() method for defining global id fields, derived from the type Name and Id.
If your underlying type has a name conflict on the field id, the "local" Id will be prefixed with the type name,
e.g. Droid.Id -> droidId
public class Droid
{
public string DroidId { get; set; }
public string Name { get; set; }
}
public class DroidType : NodeGraphType<Droid>
{
public DroidType()
{
Name = "Droid";
Id(d => d.DroidId); // adds an id Field as well as the `Droid` id field
Field<StringGraphType>("name", "The name of the droid.");
}
public override Droid GetById(string droidId) {
return StarWarsData.GetDroidByIdAsync(droidId);
}
}Relay mutations specify a few constraints on top of the general GraphQL mutations. To accommodate this, there are mutation specific GraphTypes provided.
The top level mutation type attached to the GraphQL Schema
public class StarWarsMutation : MutationGraphType
{
public StarWarsMutation() {
Mutation<CreateDroidInput, CreateDroidPayload>("createDroid");
Mutation<DeleteDroidInput, DeleteDroidPayload>("deleteDroid");
}
}
public class StarWarsSchema : Schema
{
public StarWarsSchema() {
Query = new StarWarsQuery();
Mutation = new StarWarsMutation();
}
}An simple base class that defines a clientMutationId field. functionally identical to InputObjectGraphType otherwise
MutationPayloadGraphType<TSource, TOut>, MutationPayloadGraphType<TSource>, MutationPayloadGraphType
The output ObjectGraphType containing the mutation payload, functionally similar to an ObjectGraphType with the
addition of requiring a MutateAndGetPayload() method used to resolve the payload from the inputs.
public class CreateDroidPayload : MutationPayloadGraphType<DroidPayload, Task<DroidPayload>>
{
public CreateDroidPayload()
{
Name = "CreateDroidPayload";
Field(
name: "droid",
type: typeof(Droid));
}
public override async Task<DroidPayload> MutateAndGetPayload(MutationInputs inputs)
{
string name = inputs.Get<string>("name");
Droid newDroid = await StarWarsData.CreateDroidAsync(name)
return new DroidPayload {
Droid = newDroid
};
}
}Luckily GraphQL-dotnet already provides helpful utilities for creating connection fields, on GraphTypes. In addition
included here are a few more helpful methods for creating relay compatible Connections from IEnumerables.
Creates a connection from an existing list of objects.
public class Droid
{
public string DroidId { get; set; }
public string Name { get; set; }
public IEnumerable<Droid> Friends { get; set; }
}
public class DroidType : ObjectGraphType<Droid>
{
public DroidType()
{
Name = "Droid";
Field<StringGraphType>("name", "The name of the droid.");
Connection<DroidType>()
.Name("friends")
.Resolve(context =>
ConnectionUtils.ToConnection(c.Source.Friends, context));
}
}ConnectionUtils.ToConnection(IEnumerable items, ResolveConnectionContext context, int sliceStartIndex, int totalCount)
Similar to the above, but creates a connection with the correct cursors, when you only have a slice of the entire set of items. Windowing the items based on the arguments.
Convert a connection item cursor to the int index of the item in the set.
Convert an index offset to a connection cursor.
ResolveConnectionContextExtensions.ToConnection<TSource>(this IResolveConnectionContext context, IQueryable<TSource> items)
Creates a connection from an IQueryable.
public class Droid
{
public string DroidId { get; set; }
public string Name { get; set; }
public IQueryable<Droid> Friends { get; set; }
}
public class DroidType : ObjectGraphType<Droid>
{
public DroidType()
{
Name = "Droid";
Field<StringGraphType>("name", "The name of the droid.");
Connection<DroidType>()
.Name("friends")
.Resolve(context => context
.ToConnection(c.Source.Friends));
}
}This project exists thanks to all the people who contribute.
PRs are welcome! Looking for something to work on? The list of open issues is a great place to start. You can help the project by simply responding to some of the asked questions.