エラー処理 (#4)

server.go

@@ -1,6 +1,9 @@
 package main
 
 import (
+	"context"
+	"github.com/99designs/gqlgen/graphql"
+	"github.com/vektah/gqlparser/v2/gqlerror"
 	"log"
 	"net/http"
 	"os"
@@ -20,6 +23,16 @@ func main() {
 	}
 
 	srv := handler.NewDefaultServer(generated.NewExecutableSchema(generated.Config{Resolvers: &graph.Resolver{}}))
+	// エラー処理を書く
+	srv.SetErrorPresenter(func(ctx context.Context, e error) *gqlerror.Error {
+		err := graphql.DefaultErrorPresenter(ctx, e)
+		err.Message = e.Error()
+		err.Extensions = map[string]interface{}{
+			"key1": "value1",
+			"key2": "value2",
+		}
+		return err
+	})
 
 	http.Handle("/", playground.Handler("GraphQL playground", "/query"))
 	http.Handle("/query", srv)