support for custom scalars (fixes #3)

graphql.go

@@ -7,15 +7,17 @@ import (
 	opentracing "github.com/opentracing/opentracing-go"
 	"github.com/opentracing/opentracing-go/ext"
 
+	"reflect"
+
 	"github.com/neelance/graphql-go/errors"
 	"github.com/neelance/graphql-go/internal/exec"
 	"github.com/neelance/graphql-go/internal/query"
 	"github.com/neelance/graphql-go/internal/schema"
 )
 
 func ParseSchema(schemaString string, resolver interface{}) (*Schema, error) {
-	b, err := New().Parse(schemaString)
-	if err != nil {
+	b := New()
+	if err := b.Parse(schemaString); err != nil {
 		return nil, err
 	}
 	return b.ApplyResolver(resolver)
@@ -33,11 +35,12 @@ func New() *SchemaBuilder {
 	}
 }
 
-func (b *SchemaBuilder) Parse(schemaString string) (*SchemaBuilder, error) {
-	if err := b.schema.Parse(schemaString); err != nil {
-		return nil, err
-	}
-	return b, nil
+func (b *SchemaBuilder) Parse(schemaString string) error {
+	return b.schema.Parse(schemaString)
+}
+
+func (b *SchemaBuilder) AddCustomScalar(name string, scalar *ScalarConfig) {
+	exec.AddCustomScalar(b.schema, name, scalar.ReflectType, scalar.CoerceInput)
 }
 
 func (b *SchemaBuilder) ApplyResolver(resolver interface{}) (*Schema, error) {
@@ -104,3 +107,8 @@ func SchemaToJSON(schemaString string) ([]byte, error) {
 
 	return json.Marshal(result)
 }
+
+type ScalarConfig struct {
+	ReflectType reflect.Type
+	CoerceInput func(input interface{}) (interface{}, error)
+}

graphql_test.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"testing"
+	"time"
 
 	"github.com/neelance/graphql-go/example/starwars"
 )
@@ -34,8 +35,15 @@ func (r *theNumberResolver) ChangeTheNumber(args *struct{ NewNumber int32 }) *th
 	return r
 }
 
+type timeResolver struct{}
+
+func (r *timeResolver) AddHour(args *struct{ Time time.Time }) time.Time {
+	return args.Time.Add(time.Hour)
+}
+
 var tests = []struct {
 	name      string
+	setup     func(b *SchemaBuilder)
 	schema    string
 	variables map[string]interface{}
 	resolver  interface{}
@@ -1070,12 +1078,53 @@ var tests = []struct {
 			}
 		`,
 	},
+
+	{
+		name: "Time",
+		setup: func(b *SchemaBuilder) {
+			b.AddCustomScalar("Time", Time)
+		},
+		schema: `
+			schema {
+				query: Query
+			}
+
+			type Query {
+				addHour(time: Time = "2001-02-03T04:05:06Z"): Time!
+			}
+		`,
+		resolver: &timeResolver{},
+		query: `
+			query($t: Time!) {
+				a: addHour(time: $t)
+				b: addHour
+			}
+		`,
+		variables: map[string]interface{}{
+			"t": time.Date(2000, 2, 3, 4, 5, 6, 0, time.UTC),
+		},
+		result: `
+			{
+				"a": "2000-02-03T05:05:06Z",
+				"b": "2001-02-03T05:05:06Z"
+			}
+		`,
+	},
 }
 
 func TestAll(t *testing.T) {
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			schema, err := ParseSchema(test.schema, test.resolver)
+			b := New()
+			if test.setup != nil {
+				test.setup(b)
+			}
+
+			if err := b.Parse(test.schema); err != nil {
+				t.Fatal(err)
+			}
+
+			schema, err := b.ApplyResolver(test.resolver)
 			if err != nil {
 				t.Fatal(err)
 			}

internal/exec/exec.go

@@ -315,7 +315,11 @@ func makeInputObjectExec(s *schema.Schema, obj *common.InputMap, typ reflect.Typ
 		}
 
 		if f.Default != nil {
-			defaultStruct.FieldByIndex(fe.fieldIndex).Set(fe.exec.eval(f.Default.Eval(nil)))
+			defaultValue, err := coerceValue(f.Type, f.Default.Eval(nil))
+			if err != nil {
+				return nil, err
+			}
+			defaultStruct.FieldByIndex(fe.fieldIndex).Set(fe.exec.eval(defaultValue))
 		}
 
 		fields = append(fields, fe)
@@ -449,7 +453,7 @@ func coerceInputObject(io *common.InputMap, variables map[string]interface{}) (m
 			coerced[iv.Name] = iv.Default.Eval(nil)
 			continue
 		}
-		c, err := coerceInputValue(iv, value)
+		c, err := coerceValue(iv.Type, value)
 		if err != nil {
 			return nil, err
 		}
@@ -458,8 +462,8 @@ func coerceInputObject(io *common.InputMap, variables map[string]interface{}) (m
 	return coerced, nil
 }
 
-func coerceInputValue(iv *common.InputValue, value interface{}) (interface{}, error) {
-	t, _ := unwrapNonNull(iv.Type)
+func coerceValue(typ common.Type, value interface{}) (interface{}, error) {
+	t, _ := unwrapNonNull(typ)
 	switch t := t.(type) {
 	case *scalar:
 		return t.coerceInput(value)

internal/exec/scalar.go

@@ -64,3 +64,11 @@ func AddBuiltinScalars(s *schema.Schema) {
 		s.Types[scalar.name] = scalar
 	}
 }
+
+func AddCustomScalar(s *schema.Schema, name string, reflectType reflect.Type, coerceInput func(input interface{}) (interface{}, error)) {
+	s.Types[name] = &scalar{
+		name:        name,
+		reflectType: reflectType,
+		coerceInput: coerceInput,
+	}
+}

internal/query/query.go

@@ -74,16 +74,20 @@ func (Field) isSelection()          {}
 func (FragmentSpread) isSelection() {}
 func (InlineFragment) isSelection() {}
 
-func Parse(queryString string, resolver common.Resolver) (doc *Document, err *errors.QueryError) {
+func Parse(queryString string, resolver common.Resolver) (*Document, *errors.QueryError) {
 	sc := &scanner.Scanner{
 		Mode: scanner.ScanIdents | scanner.ScanInts | scanner.ScanFloats | scanner.ScanStrings,
 	}
 	sc.Init(strings.NewReader(queryString))
 
 	l := lexer.New(sc)
-	err = l.CatchSyntaxError(func() {
+	var doc *Document
+	err := l.CatchSyntaxError(func() {
 		doc = parseDocument(l)
 	})
+	if err != nil {
+		return nil, err
+	}
 
 	for _, op := range doc.Operations {
 		for _, v := range op.Vars.Fields {
@@ -95,7 +99,7 @@ func Parse(queryString string, resolver common.Resolver) (doc *Document, err *er
 		}
 	}
 
-	return
+	return doc, nil
 }
 
 func parseDocument(l *lexer.Lexer) *Document {

time.go

@@ -0,0 +1,24 @@
+package graphql
+
+import (
+	"fmt"
+	"reflect"
+	"time"
+)
+
+var Time = &ScalarConfig{
+	ReflectType: reflect.TypeOf(time.Time{}),
+	CoerceInput: func(input interface{}) (interface{}, error) {
+		switch input := input.(type) {
+		case time.Time:
+			return input, nil
+		case string:
+			t, err := time.Parse(time.RFC3339, input)
+			return t, err
+		case int:
+			return time.Unix(int64(input), 0), nil
+		default:
+			return nil, fmt.Errorf("could not convert %v (%t) to time", input, input)
+		}
+	},
+}