fix handling null default values for input fields with object or list types (wundergraph#707)

Author: pvormste

v2/pkg/astnormalization/inject_input_default_values.go

@@ -171,13 +171,17 @@ func (v *inputFieldDefaultInjectionVisitor) processObjectOrListInput(fieldType i
 	finalVal := defaultValue
 	replaced := false
 	valIsList := valType == jsonparser.Array
-	if fieldIsList && valIsList {
+
+	switch {
+	case valType == jsonparser.Null:
+		replaced = true
+	case fieldIsList && valIsList:
 		_, err := jsonparser.ArrayEach(varVal, v.jsonWalker(typeDoc.ResolveListOrNameType(fieldType), defaultValue, &node, typeDoc, &finalVal, &replaced))
 		if err != nil {
 			return nil, false, err
 
 		}
-	} else if !fieldIsList && !valIsList {
+	case !fieldIsList && !valIsList:
 		finalVal, replaced, err = v.recursiveInjectInputFields(node.Ref, defaultValue)
 		if err != nil {
 			return nil, false, err

v2/pkg/astnormalization/inject_input_default_values_test.go

@@ -32,6 +32,20 @@ type Mutation {
   mutationSimpleInputList(in: [SimpleTestInput]): String
   mutationUseCustomScalar(in: CustomScalar!): String
   mutationUseCustomScalarList(in: [CustomScalar!]): String
+
+  testNullDefaultValuesForObjectAndList(data: NullDefaultForObjectAndListField!): String!
+  testNullDefaultValueForFields(data: NullDefaultFields!): String!
+}
+
+input NullDefaultForObjectAndListField {
+  other: String!
+  nested: NullDefaultFields = null
+  nestedList: [NullDefaultFields] = null
+}
+
+input NullDefaultFields {
+  a: String = null
+  b: Int = null
 }
 
 input MultiNestedInput {
@@ -264,4 +278,31 @@ func TestInputDefaultValueExtraction(t *testing.T) {
 			  mutationUseCustomScalarList(in: $a)
 			}`, `{"a":[{"test": "testval"}]}`, `{"a":[{"test": "testval"}]}`)
 	})
+
+	t.Run("null default value for object and list fields", func(t *testing.T) {
+		runWithVariables(t, extractVariables, testInputDefaultSchema, `
+			mutation TestDefaults($data: NullDefaultForObjectAndListField!) {
+  				testNullDefaultValuesForObjectAndList(data: $data)
+			}`, "", `
+			mutation TestDefaults($data: NullDefaultForObjectAndListField!) {
+  				testNullDefaultValuesForObjectAndList(data: $data)
+			}`, `{"data":{"other":"value"}}`,
+			`{"data":{"other":"value","nested":null,"nestedList":null}}`,
+			func(walker *astvisitor.Walker) {
+				injectInputFieldDefaults(walker)
+			})
+	})
+
+	t.Run("null default value for scalar fields", func(t *testing.T) {
+		runWithVariables(t, extractVariables, testInputDefaultSchema, `
+			mutation{
+  				testNullDefaultValueForFields(data: {})
+			}`, "", `
+			mutation($a: NullDefaultFields!) {
+  				testNullDefaultValueForFields(data: $a)
+			}`, "", `{"a":{"a":null,"b":null}}`,
+			func(walker *astvisitor.Walker) {
+				injectInputFieldDefaults(walker)
+			})
+	})
 }

v2/pkg/astnormalization/variables_default_value_extraction_test.go

@@ -29,7 +29,7 @@ const (
 		}
 		type Mutation {
 			simple(input: String = "foo"): String
-			mixed(a: String, b: String, input: String = "foo", nonNullInput: String! = "bar"): String
+			mixed(a: String, b: String, input: String = "foo", nonNullInput: String! = "bar", nullableWithNullDefault: String = null): String
 		}
 		scalar String
 		input ComplexInput {
@@ -70,9 +70,9 @@ func TestVariablesDefaultValueExtraction(t *testing.T) {
 				mutation simple($a: String) {
 			  		mixed(a: $a, b: "bar")
 				}`, "", `
-				mutation simple($a: String, $b: String, $c: String!) {
-			  		mixed(a: $a, b: "bar", input: $b, nonNullInput: $c)
-				}`, `{"a":"aaa"}`, `{"c":"bar","b":"foo","a":"aaa"}`)
+				mutation simple($a: String, $b: String, $c: String!, $d: String) {
+			  		mixed(a: $a, b: "bar", input: $b, nonNullInput: $c, nullableWithNullDefault: $d)
+				}`, `{"a":"aaa"}`, `{"d":null,"c":"bar","b":"foo","a":"aaa"}`)
 		})
 	})
 
@@ -261,9 +261,19 @@ func TestVariablesDefaultValueExtraction(t *testing.T) {
 			mutation simple($a: String = "bar", $b: String = "bazz") {
 				mixed(a: $a, b: $b)
 			}`, "", `
-			mutation simple($a: String, $b: String, $c: String, $d: String!) {
-				mixed(a: $a, b: $b, input: $c, nonNullInput: $d)
-			}`, `{"a":"aaa"}`, `{"d":"bar","c":"foo","b":"bazz","a":"aaa"}`)
+			mutation simple($a: String, $b: String, $c: String, $d: String!, $e: String) {
+				mixed(a: $a, b: $b, input: $c, nonNullInput: $d, nullableWithNullDefault: $e)
+			}`, `{"a":"aaa"}`, `{"e":null,"d":"bar","c":"foo","b":"bazz","a":"aaa"}`)
 
 	})
+
+	t.Run("variable with null default value", func(t *testing.T) {
+		runWithVariablesDefaultValues(t, extractVariablesDefaultValue, variablesDefaultValueExtractionDefinition, `
+			query q($data: ComplexInput = null) {
+				complex(input: $data)
+			}`, "", `
+			query q($data: ComplexInput) {
+				complex(input: $data)
+			}`, ``, `{"data":null}`)
+	})
 }