1 files changed, 30 insertions, 0 deletions
diff --git a/vendor/github.com/vektah/gqlparser/validator/rules/single_field_subscriptions.go b/vendor/github.com/vektah/gqlparser/validator/rules/single_field_subscriptions.go
new file mode 100644
index 00000000..53003c11
--- /dev/null
+++ b/vendor/github.com/vektah/gqlparser/validator/rules/single_field_subscriptions.go
@@ -0,0 +1,30 @@
+package validator
+
+import (
+	"strconv"
+
+	"github.com/vektah/gqlparser/ast"
+	. "github.com/vektah/gqlparser/validator"
+)
+
+func init() {
+	AddRule("SingleFieldSubscriptions", func(observers *Events, addError AddErrFunc) {
+		observers.OnOperation(func(walker *Walker, operation *ast.OperationDefinition) {
+			if operation.Operation != ast.Subscription {
+				return
+			}
+
+			if len(operation.SelectionSet) > 1 {
+				name := "Anonymous Subscription"
+				if operation.Name != "" {
+					name = `Subscription ` + strconv.Quote(operation.Name)
+				}
+
+				addError(
+					Message(`%s must select only one top level field.`, name),
+					At(operation.SelectionSet[1].GetPosition()),
+				)
+			}
+		})
+	})
+}