added support for argument fields (#17)

* added support for argument fields

* use the previous value of the OperationType

Author: Cotofana Radu

src/GraphQL.Authorization/AuthorizationValidationRule.cs

@@ -1,4 +1,5 @@
-using GraphQL.Language.AST;
+using System.Linq;
+using GraphQL.Language.AST;
 using GraphQL.Types;
 using GraphQL.Validation;
 
@@ -34,6 +35,16 @@ public INodeVisitor Validate(ValidationContext context)
                     CheckAuth(astType, type, userContext, context, operationType);
                 });
 
+                _.Match<ObjectField>(objectFieldAst =>
+                {
+                    var argumentType = context.TypeInfo.GetArgument().ResolvedType.GetNamedType() as IComplexGraphType;
+                    if (argumentType == null)
+                        return;
+
+                    var fieldType = argumentType.Fields.First(p => p.Name == objectFieldAst.Name);
+                    CheckAuth(objectFieldAst, fieldType, userContext, context, operationType);
+                });
+
                 _.Match<Field>(fieldAst =>
                 {
                     var fieldDef = context.TypeInfo.GetFieldDef();