Fix missing argument default values

introspection.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 
 	"github.com/pkg/errors"
+	"github.com/vektah/gqlparser/v2"
 	"github.com/vektah/gqlparser/v2/ast"
 )
 
@@ -91,7 +92,6 @@ func IntrospectWithRetrier(retrier Retrier) *IntrospectOptions {
 // IntrospectRemoteSchema is used to build a RemoteSchema by firing the introspection query
 // at a remote service and reconstructing the schema object from the response
 func IntrospectRemoteSchema(url string, opts ...*IntrospectOptions) (*RemoteSchema, error) {
-
 	// introspect the schema at the designated url
 	schema, err := IntrospectAPI(NewSingleRequestQueryer(url), opts...)
 	if err != nil {
@@ -244,7 +244,6 @@ func IntrospectAPI(queryer Queryer, opts ...*IntrospectOptions) (*ast.Schema, er
 		}
 
 		if len(remoteType.Interfaces) > 0 {
-
 			// each interface value needs to be added to the list
 			for _, iFace := range remoteType.Interfaces {
 				// if there is no name
@@ -271,11 +270,15 @@ func IntrospectAPI(queryer Queryer, opts ...*IntrospectOptions) (*ast.Schema, er
 
 		for _, field := range remoteType.Fields {
 			// add the field to the list
+			args, err := introspectionConvertArgList(field.Args)
+			if err != nil {
+				return nil, err
+			}
 			fields = append(fields, &ast.FieldDefinition{
 				Name:        field.Name,
 				Type:        introspectionUnmarshalTypeRef(&field.Type),
 				Description: field.Description,
-				Arguments:   introspectionConvertArgList(field.Args),
+				Arguments:   args,
 			})
 		}
 
@@ -306,11 +309,15 @@ func IntrospectAPI(queryer Queryer, opts ...*IntrospectOptions) (*ast.Schema, er
 		}
 
 		// save the directive definition to the schema
+		args, err := introspectionConvertArgList(directive.Args)
+		if err != nil {
+			return nil, err
+		}
 		schema.Directives[directive.Name] = &ast.DirectiveDefinition{
 			Position:    &ast.Position{Src: &ast.Source{}},
 			Name:        directive.Name,
 			Description: directive.Description,
-			Arguments:   introspectionConvertArgList(directive.Args),
+			Arguments:   args,
 			Locations:   locations,
 		}
 		switch directive.Name {
@@ -332,19 +339,24 @@ func addPossibleTypeOnce(schema *ast.Schema, name string, definition *ast.Defini
 	schema.AddPossibleType(name, definition)
 }
 
-func introspectionConvertArgList(args []IntrospectionInputValue) ast.ArgumentDefinitionList {
+func introspectionConvertArgList(args []IntrospectionInputValue) (ast.ArgumentDefinitionList, error) {
 	result := ast.ArgumentDefinitionList{}
 
 	// we need to add each argument to the field
 	for _, argument := range args {
+		defaultValue, err := introspectionUnmarshalArgumentDefaultValue(argument)
+		if err != nil {
+			return nil, err
+		}
 		result = append(result, &ast.ArgumentDefinition{
-			Name:        argument.Name,
-			Description: argument.Description,
-			Type:        introspectionUnmarshalTypeRef(&argument.Type),
+			Name:         argument.Name,
+			Description:  argument.Description,
+			Type:         introspectionUnmarshalTypeRef(&argument.Type),
+			DefaultValue: defaultValue,
 		})
 	}
 
-	return result
+	return result, nil
 }
 
 func introspectionUnmarshalType(schemaType IntrospectionQueryFullType) *ast.Definition {
@@ -387,6 +399,29 @@ func introspectionUnmarshalType(schemaType IntrospectionQueryFullType) *ast.Defi
 	return definition
 }
 
+// introspectionUnmarshalArgumentDefaultValue returns the *ast.Value form of an argument's default value.
+//
+// The tricky part here is the default value comes in as a string, so it's non-trivial to unmarshal.
+// This takes advantage of gqlparser's loose validation when parsing an argument's default value even if the type is wrong (to avoid including full definitions of custom types).
+// This validation will likely become stricter with time -- hopefully the library will provide some additional tools to parse the default value separately.
+func introspectionUnmarshalArgumentDefaultValue(argument IntrospectionInputValue) (*ast.Value, error) {
+	if argument.DefaultValue == "" {
+		return nil, nil
+	}
+	const inputValueQuery = `
+type Query {
+	field(input: String = %s): String
+}
+`
+	schema, err := gqlparser.LoadSchema(&ast.Source{
+		Input: fmt.Sprintf(inputValueQuery, argument.DefaultValue),
+	})
+	if err != nil {
+		return nil, err
+	}
+	return schema.Query.Fields.ForName("field").Arguments.ForName("input").DefaultValue, nil
+}
+
 // a mapping of marshaled directive locations to their parsed equivalent
 var directiveLocationMap map[string]ast.DirectiveLocation
 

introspection_test.go

@@ -3,6 +3,7 @@ package graphql
 import (
 	"bytes"
 	"context"
+	_ "embed"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -1033,7 +1034,6 @@ func TestIntrospectWithHTTPClient(t *testing.T) {
 			opt := IntrospectWithHTTPClient(row.Client)
 			queryer = opt.Apply(queryer).(*SingleRequestQueryer)
 			assert.Equal(t, row.Client, queryer.queryer.Client)
-
 		})
 	}
 }
@@ -1518,3 +1518,45 @@ query {
 `)
 	assert.Nil(t, err, "Spreading object fragment on matching interface should be allowed")
 }
+
+//go:embed testdata/introspect_default_values.json
+var introspectionDefaultValuesJSON string
+
+// TestIntrospectDirectivesDefaultValue verifies fix for https://github.com/nautilus/graphql/issues/40
+func TestIntrospectDirectivesDefaultValue(t *testing.T) {
+	t.Parallel()
+
+	schema, err := IntrospectAPI(&mockJSONQueryer{
+		JSONResult: introspectionDefaultValuesJSON,
+	})
+	require.NoError(t, err)
+
+	var schemaBuffer bytes.Buffer
+	formatter.NewFormatter(&schemaBuffer).FormatSchema(schema)
+
+	expectedSchema, err := gqlparser.LoadSchema(&ast.Source{Input: `
+directive @hello(
+  foo: String! = "foo"
+  bar: Int = 1
+  baz: Boolean = true
+  biff: Float = 1.23
+  boo: [String] = ["boo"]
+  bah: HelloInput = {humbug: "humbug"}
+  blah: HelloEnum = HELLO_1
+) on FIELD_DEFINITION
+
+input HelloInput {
+  humbug: String
+}
+
+enum HelloEnum {
+  HELLO_1
+  HELLO_2
+  HELLO_3
+}
+	`})
+	require.NoError(t, err)
+	var expectedBuffer bytes.Buffer
+	formatter.NewFormatter(&expectedBuffer).FormatSchema(expectedSchema)
+	assert.Equal(t, expectedBuffer.String(), schemaBuffer.String())
+}

testdata/introspect_default_values.json

@@ -0,0 +1,200 @@
+{
+	"__schema": {
+		"queryType": {
+			"name": "Query"
+		},
+		"mutationType": null,
+		"subscriptionType": null,
+		"types": [
+			{
+				"kind": "SCALAR",
+				"name": "Boolean",
+				"description": "The `Boolean` scalar type represents `true` or `false`.",
+				"fields": null,
+				"inputFields": null,
+				"interfaces": null,
+				"enumValues": null,
+				"possibleTypes": null
+			},
+			{
+				"kind": "SCALAR",
+				"name": "Float",
+				"description": "The `Float` scalar type represents signed double-precision fractional values as specified by [IEEE 754](http://en.wikipedia.org/wiki/IEEE_floating_point).",
+				"fields": null,
+				"inputFields": null,
+				"interfaces": null,
+				"enumValues": null,
+				"possibleTypes": null
+			},
+			{
+				"kind": "ENUM",
+				"name": "HelloEnum",
+				"description": null,
+				"fields": null,
+				"inputFields": null,
+				"interfaces": null,
+				"enumValues": [
+					{
+						"name": "HELLO_1",
+						"description": null,
+						"isDeprecated": false,
+						"deprecationReason": null
+					},
+					{
+						"name": "HELLO_2",
+						"description": null,
+						"isDeprecated": false,
+						"deprecationReason": null
+					},
+					{
+						"name": "HELLO_3",
+						"description": null,
+						"isDeprecated": false,
+						"deprecationReason": null
+					}
+				],
+				"possibleTypes": null
+			},
+			{
+				"kind": "INPUT_OBJECT",
+				"name": "HelloInput",
+				"description": null,
+				"fields": null,
+				"inputFields": [
+					{
+						"name": "humbug",
+						"description": null,
+						"type": {
+							"kind": "SCALAR",
+							"name": "String",
+							"ofType": null
+						},
+						"defaultValue": null
+					}
+				],
+				"interfaces": null,
+				"enumValues": null,
+				"possibleTypes": null
+			},
+			{
+				"kind": "SCALAR",
+				"name": "ID",
+				"description": "The `ID` scalar type represents a unique identifier, often used to refetch an object or as key for a cache. The ID type appears in a JSON response as a String; however, it is not intended to be human-readable. When expected as an input type, any string (such as `\"4\"`) or integer (such as `4`) input value will be accepted as an ID.",
+				"fields": null,
+				"inputFields": null,
+				"interfaces": null,
+				"enumValues": null,
+				"possibleTypes": null
+			},
+			{
+				"kind": "SCALAR",
+				"name": "Int",
+				"description": "The `Int` scalar type represents non-fractional signed whole numeric values. Int can represent values between -(2^31) and 2^31 - 1.",
+				"fields": null,
+				"inputFields": null,
+				"interfaces": null,
+				"enumValues": null,
+				"possibleTypes": null
+			},
+			{
+				"kind": "SCALAR",
+				"name": "String",
+				"description": "The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.",
+				"fields": null,
+				"inputFields": null,
+				"interfaces": null,
+				"enumValues": null,
+				"possibleTypes": null
+			}
+		],
+		"directives": [
+			{
+				"name": "hello",
+				"description": null,
+				"locations": [
+					"FIELD_DEFINITION"
+				],
+				"args": [
+					{
+						"name": "foo",
+						"description": null,
+						"type": {
+							"kind": "NON_NULL",
+							"name": null,
+							"ofType": {
+								"kind": "SCALAR",
+								"name": "String",
+								"ofType": null
+							}
+						},
+						"defaultValue": "\"foo\""
+					},
+					{
+						"name": "bar",
+						"description": null,
+						"type": {
+							"kind": "SCALAR",
+							"name": "Int",
+							"ofType": null
+						},
+						"defaultValue": "1"
+					},
+					{
+						"name": "baz",
+						"description": null,
+						"type": {
+							"kind": "SCALAR",
+							"name": "Boolean",
+							"ofType": null
+						},
+						"defaultValue": "true"
+					},
+					{
+						"name": "biff",
+						"description": null,
+						"type": {
+							"kind": "SCALAR",
+							"name": "Float",
+							"ofType": null
+						},
+						"defaultValue": "1.23"
+					},
+					{
+						"name": "boo",
+						"description": null,
+						"type": {
+							"kind": "LIST",
+							"name": null,
+							"ofType": {
+								"kind": "SCALAR",
+								"name": "String",
+								"ofType": null
+							}
+						},
+						"defaultValue": "[\"boo\"]"
+					},
+					{
+						"name": "bah",
+						"description": null,
+						"type": {
+							"kind": "INPUT_OBJECT",
+							"name": "HelloInput",
+							"ofType": null
+						},
+						"defaultValue": "{humbug: \"humbug\"}"
+					},
+					{
+						"name": "blah",
+						"description": null,
+						"type": {
+							"kind": "ENUM",
+							"name": "HelloEnum",
+							"ofType": null
+						},
+						"defaultValue": "HELLO_1"
+					}
+				]
+			}
+		]
+	}
+}