From c67a10208e52065691f4b16e52d457e123d9de08 Mon Sep 17 00:00:00 2001
From: MURAOKA Taro <koron.kaoriya@gmail.com>
Date: Sat, 27 Jun 2020 10:35:41 +0900
Subject: [PATCH] GetArgumentValues: public version of getArgumentValues()

to write custom validation rules, sometimes it want to access field's
argument values, but getArgumentValues() is private.  this creates
public version of getArgumentValues() to access from those validation
rules.
---
 graphql_test.go | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
 values.go       | 11 +++++++++
 2 files changed, 74 insertions(+)

diff --git a/graphql_test.go b/graphql_test.go
index f370cfc7..9cc178d9 100644
--- a/graphql_test.go
+++ b/graphql_test.go
@@ -327,3 +327,66 @@ func TestQueryWithCustomRule(t *testing.T) {
 		}
 	}
 }
+
+// TestCustomRuleWithArgs tests graphql.GetArgumentValues() be able to access
+// field's argument values from custom validation rule.
+func TestCustomRuleWithArgs(t *testing.T) {
+	fieldDef, ok := testutil.StarWarsSchema.QueryType().Fields()["human"]
+	if !ok {
+		t.Fatal("can't retrieve \"human\" field definition")
+	}
+
+	// a custom validation rule to extract argument values of "human" field.
+	var actual map[string]interface{}
+	enter := func(p visitor.VisitFuncParams) (string, interface{}) {
+		// only interested in "human" field.
+		fieldNode, ok := p.Node.(*ast.Field)
+		if !ok || fieldNode.Name == nil || fieldNode.Name.Value != "human" {
+			return visitor.ActionNoChange, nil
+		}
+		// extract argument values by graphql.GetArgumentValues().
+		actual = graphql.GetArgumentValues(fieldDef.Args, fieldNode.Arguments, nil)
+		return visitor.ActionNoChange, nil
+	}
+	checkHumanArgs := func(context *graphql.ValidationContext) *graphql.ValidationRuleInstance {
+		return &graphql.ValidationRuleInstance{
+			VisitorOpts: &visitor.VisitorOptions{
+				KindFuncMap: map[string]visitor.NamedVisitFuncs{
+					kinds.Field: {Enter: enter},
+				},
+			},
+		}
+	}
+
+	for _, tc := range []struct {
+		query      string
+		expected   map[string]interface{}
+	}{
+		{
+			`query { human(id: "1000") { name } }`,
+			map[string]interface{}{"id": "1000"},
+		},
+		{
+			`query { human(id: "1002") { name } }`,
+			map[string]interface{}{"id": "1002"},
+		},
+		{
+			`query { human(id: "9999") { name } }`,
+			map[string]interface{}{"id": "9999"},
+		},
+	} {
+		actual = nil
+		params := graphql.Params{
+			Schema:          testutil.StarWarsSchema,
+			RequestString:   tc.query,
+			ValidationRules: append(graphql.SpecifiedRules, checkHumanArgs),
+		}
+		result := graphql.Do(params)
+		if len(result.Errors) > 0 {
+			t.Fatalf("wrong result, unexpected errors: %v", result.Errors)
+		}
+		if !reflect.DeepEqual(actual, tc.expected) {
+			t.Fatalf("unexpected result: want=%+v got=%+v", tc.expected, actual)
+		}
+	}
+}
diff --git a/values.go b/values.go
index 06c08af6..8dc5210f 100644
--- a/values.go
+++ b/values.go
@@ -67,6 +67,17 @@ func getArgumentValues(
 	return results
 }
 
+// GetArgumentValues prepares an object map of argument values given a list of
+// argument definitions and list of argument AST nodes.
+//
+// This is an exported version of getArgumentValues(), to ease writing custom
+// validation rules.
+func GetArgumentValues(
+	argDefs []*Argument, argASTs []*ast.Argument,
+	variableValues map[string]interface{}) map[string]interface{} {
+	return getArgumentValues(argDefs, argASTs, variableValues)
+}
+
 // Given a variable definition, and any value of input, return a value which
 // adheres to the variable definition, or throw an error.
 func getVariableValue(schema Schema, definitionAST *ast.VariableDefinition, input interface{}) (interface{}, error) {