GraphQL.NET - Exporting the GraphQL schema

In case you didn’t notice, I’m a big fan of GraphQL. Most of the time I use GraphQL.NET and more specifically the GraphType first approach; https://graphql-dotnet.github.io/docs/getting-started/introduction#graphtype-first-approach.

The disadvantage of this approach is that you don’t have a schema file but that the schema is generated dynamically from your mappings.

Why is this a problem?

There are a number of tools that expect to work from a schema file and try to import it.

Luckily it is not that hard to create some extra middleware that allows us to export the schema from a GraphQL.NET service:

	public class SchemaMiddleware
	{
	private readonly RequestDelegate _next;
	public SchemaMiddleware(RequestDelegate next)
	{
	_next = next;
	}
	public async Task Invoke(HttpContext context, OrdersSchema schema)
	{
	using (var printer = new SchemaPrinter(schema))
	{
	context.Response.ContentType = "application/text";
	context.Response.StatusCode = (int)HttpStatusCode.OK;
	await context.Response.WriteAsync(printer.Print());
	return;
	}
	}
	}

view raw SchemaMiddleware.cs hosted with ❤ by GitHub

To invoke this middleware we add it inside our Startup configuration:

	public void Configure(IApplicationBuilder app, IHostingEnvironment env)
	{
	if (env.IsDevelopment())
	{
	app.UseDeveloperExceptionPage();
	}
	app.UseDefaultFiles();
	app.UseStaticFiles();
	app.UseWebSockets();
	app.UseGraphQLWebSocket<OrdersSchema>(new GraphQLWebSocketsOptions());
	app.UseGraphQLHttp<OrdersSchema>(new GraphQLHttpOptions());
	app.Map("/schema.graphql", config => config.UseMiddleware<SchemaMiddleware>());
	}

view raw StartupGraphQL.cs hosted with ❤ by GitHub