add default args

codegen/object.go

@@ -35,8 +35,9 @@ type Field struct {
 type FieldArgument struct {
 	*Type
 
-	GQLName string  // The name of the argument in graphql
-	Object  *Object // A link back to the parent object
+	GQLName string      // The name of the argument in graphql
+	Object  *Object     // A link back to the parent object
+	Default interface{} // The default value
 }
 
 type Objects []*Object

codegen/object_build.go

@@ -98,11 +98,17 @@ func buildObject(types NamedTypes, typ *schema.Object) *Object {
 	for _, field := range typ.Fields {
 		var args []FieldArgument
 		for _, arg := range field.Args {
-			args = append(args, FieldArgument{
+			newArg := FieldArgument{
 				GQLName: arg.Name.Name,
 				Type:    types.getType(arg.Type),
 				Object:  obj,
-			})
+			}
+
+			if arg.Default != nil {
+				newArg.Default = arg.Default.Value(nil)
+				newArg.StripPtr()
+			}
+			args = append(args, newArg)
 		}
 
 		obj.Fields = append(obj.Fields, Field{

codegen/templates/args.gotpl

@@ -11,5 +11,18 @@
 					return graphql.Null
 				{{- end }}
 			}
+		} {{ if $arg.Default }} else {
+			tmp := {{ $arg.Default | dump }}
+			var err error
+			{{$arg.Unmarshal (print "arg" $i) "tmp" }}
+			if err != nil {
+				ec.Error(err)
+				{{- if $arg.Object.Stream }}
+					return nil
+				{{- else }}
+					return graphql.Null
+				{{- end }}
+			}
 		}
+		{{end }}
 	{{- end -}}

codegen/templates/templates.go

@@ -4,7 +4,9 @@ package templates
 
 import (
 	"bytes"
+	"fmt"
 	"strconv"
+	"strings"
 	"text/template"
 	"unicode"
 
@@ -16,6 +18,7 @@ func Run(e *codegen.Build) (*bytes.Buffer, error) {
 		"ucFirst": ucFirst,
 		"lcFirst": lcFirst,
 		"quote":   strconv.Quote,
+		"dump":    dump,
 	})
 
 	for filename, data := range data {
@@ -52,3 +55,36 @@ func lcFirst(s string) string {
 	r[0] = unicode.ToLower(r[0])
 	return string(r)
 }
+
+func dump(val interface{}) string {
+	switch val := val.(type) {
+	case int:
+		return strconv.Itoa(val)
+	case float64:
+		return fmt.Sprintf("%f", val)
+	case string:
+		return strconv.Quote(val)
+	case bool:
+		return strconv.FormatBool(val)
+	case nil:
+		return "nil"
+	case []interface{}:
+		var parts []string
+		for _, part := range val {
+			parts = append(parts, dump(part))
+		}
+		return "[]interface{}{" + strings.Join(parts, ",") + "}"
+	case map[string]interface{}:
+		buf := bytes.Buffer{}
+		buf.WriteString("map[string]interface{}{")
+		for key, data := range val {
+			buf.WriteString(strconv.Quote(key))
+			buf.WriteString(":")
+			buf.WriteString(dump(data))
+		}
+		buf.WriteString("}")
+		return buf.String()
+	default:
+		panic(fmt.Errorf("unsupported type %T", val))
+	}
+}

codegen/type.go

@@ -62,6 +62,13 @@ func (t Type) IsPtr() bool {
 	return len(t.Modifiers) > 0 && t.Modifiers[0] == modPtr
 }
 
+func (t *Type) StripPtr() {
+	if !t.IsPtr() {
+		return
+	}
+	t.Modifiers = t.Modifiers[0 : len(t.Modifiers)-1]
+}
+
 func (t Type) IsSlice() bool {
 	return len(t.Modifiers) > 0 && t.Modifiers[0] == modList
 }

codegen/type_build.go

@@ -101,8 +101,8 @@ func (n NamedTypes) getType(t common.Type) *Type {
 				Modifiers: modifiers,
 			}
 
-			if t.IsInterface && t.Modifiers[len(t.Modifiers)-1] == modPtr {
-				t.Modifiers = t.Modifiers[0 : len(t.Modifiers)-1]
+			if t.IsInterface {
+				t.StripPtr()
 			}
 
 			return t

example/scalars/generated.go

@@ -118,12 +118,22 @@ func (ec *executionContext) _Query_search(field graphql.CollectedField) graphql.
 	if tmp, ok := field.Args["input"]; ok {
 		var err error
 
+		arg0, err = UnmarshalSearchArgs(tmp)
+		if err != nil {
+			ec.Error(err)
+			return graphql.Null
+		}
+	} else {
+		tmp := map[string]interface{}{"location": "37,144"}
+		var err error
+
 		arg0, err = UnmarshalSearchArgs(tmp)
 		if err != nil {
 			ec.Error(err)
 			return graphql.Null
 		}
 	}
+
 	return graphql.Defer(func() graphql.Marshaler {
 		res, err := ec.resolvers.Query_search(ec.ctx, arg0)
 		if err != nil {
@@ -751,7 +761,7 @@ func UnmarshalSearchArgs(v interface{}) (SearchArgs, error) {
 	return it, nil
 }
 
-var parsedSchema = schema.MustParse("schema {\n    query: Query\n}\n\ntype Query {\n    user(id: ID!): User\n    search(input: SearchArgs!): [User!]!\n}\n\ntype User {\n    id: ID!\n    name: String!\n    created: Timestamp\n    location: Point\n    isBanned: Boolean!\n}\n\ninput SearchArgs {\n    location: Point\n    createdAfter: Timestamp\n    isBanned: Boolean\n}\n\nscalar Timestamp\nscalar Point\n")
+var parsedSchema = schema.MustParse("schema {\n    query: Query\n}\n\ntype Query {\n    user(id: ID!): User\n    search(input: SearchArgs = {location: \"37,144\"}): [User!]!\n}\n\ntype User {\n    id: ID!\n    name: String!\n    created: Timestamp\n    location: Point\n    isBanned: Boolean!\n}\n\ninput SearchArgs {\n    location: Point\n    createdAfter: Timestamp\n    isBanned: Boolean\n}\n\nscalar Timestamp\nscalar Point\n")
 
 func (ec *executionContext) introspectSchema() *introspection.Schema {
 	return introspection.WrapSchema(parsedSchema)

example/scalars/scalar_test.go

@@ -43,6 +43,14 @@ func TestScalars(t *testing.T) {
 		require.Equal(t, int64(666), resp.Search[0].Created)
 	})
 
+	t.Run("default search location", func(t *testing.T) {
+		var resp struct{ Search []RawUser }
+
+		err := c.Post(`{ search { location } }`, &resp)
+		require.NoError(t, err)
+		require.Equal(t, "37,144", resp.Search[0].Location)
+	})
+
 	t.Run("test custom error messages", func(t *testing.T) {
 		var resp struct{ Search []RawUser }
 

example/scalars/schema.graphql

@@ -4,7 +4,7 @@ schema {
 
 type Query {
     user(id: ID!): User
-    search(input: SearchArgs!): [User!]!
+    search(input: SearchArgs = {location: "37,144"}): [User!]!
 }
 
 type User {

example/starwars/generated.go

@@ -33,7 +33,7 @@ type Resolvers interface {
 	Human_starships(ctx context.Context, obj *Human) ([]Starship, error)
 	Mutation_createReview(ctx context.Context, episode string, review Review) (*Review, error)
 
-	Query_hero(ctx context.Context, episode *string) (Character, error)
+	Query_hero(ctx context.Context, episode string) (Character, error)
 	Query_reviews(ctx context.Context, episode string, since *time.Time) ([]Review, error)
 	Query_search(ctx context.Context, text string) ([]SearchResult, error)
 	Query_character(ctx context.Context, id string) (Character, error)
@@ -347,12 +347,22 @@ func (ec *executionContext) _Human_height(field graphql.CollectedField, obj *Hum
 	if tmp, ok := field.Args["unit"]; ok {
 		var err error
 
+		arg0, err = graphql.UnmarshalString(tmp)
+		if err != nil {
+			ec.Error(err)
+			return graphql.Null
+		}
+	} else {
+		tmp := "METER"
+		var err error
+
 		arg0, err = graphql.UnmarshalString(tmp)
 		if err != nil {
 			ec.Error(err)
 			return graphql.Null
 		}
 	}
+
 	res := obj.Height(arg0)
 	return graphql.MarshalFloat(res)
 }
@@ -570,18 +580,26 @@ func (ec *executionContext) _Query(sel []query.Selection) graphql.Marshaler {
 }
 
 func (ec *executionContext) _Query_hero(field graphql.CollectedField) graphql.Marshaler {
-	var arg0 *string
+	var arg0 string
 	if tmp, ok := field.Args["episode"]; ok {
 		var err error
-		var ptr1 string
 
-		ptr1, err = graphql.UnmarshalString(tmp)
-		arg0 = &ptr1
+		arg0, err = graphql.UnmarshalString(tmp)
+		if err != nil {
+			ec.Error(err)
+			return graphql.Null
+		}
+	} else {
+		tmp := "NEWHOPE"
+		var err error
+
+		arg0, err = graphql.UnmarshalString(tmp)
 		if err != nil {
 			ec.Error(err)
 			return graphql.Null
 		}
 	}
+
 	return graphql.Defer(func() graphql.Marshaler {
 		res, err := ec.resolvers.Query_hero(ec.ctx, arg0)
 		if err != nil {
@@ -860,12 +878,22 @@ func (ec *executionContext) _Starship_length(field graphql.CollectedField, obj *
 	if tmp, ok := field.Args["unit"]; ok {
 		var err error
 
+		arg0, err = graphql.UnmarshalString(tmp)
+		if err != nil {
+			ec.Error(err)
+			return graphql.Null
+		}
+	} else {
+		tmp := "METER"
+		var err error
+
 		arg0, err = graphql.UnmarshalString(tmp)
 		if err != nil {
 			ec.Error(err)
 			return graphql.Null
 		}
 	}
+
 	res := obj.Length(arg0)
 	return graphql.MarshalFloat(res)
 }

example/starwars/resolvers.go

@@ -85,8 +85,8 @@ func (r *Resolver) Mutation_createReview(ctx context.Context, episode string, re
 	return &review, nil
 }
 
-func (r *Resolver) Query_hero(ctx context.Context, episode *string) (Character, error) {
-	if episode != nil && *episode == "EMPIRE" {
+func (r *Resolver) Query_hero(ctx context.Context, episode string) (Character, error) {
+	if episode == "EMPIRE" {
 		return r.humans["1000"], nil
 	}
 	return r.droid["2001"], nil

example/starwars/starwars_test.go

@@ -84,6 +84,17 @@ func TestStarwars(t *testing.T) {
 		require.Equal(t, 1.72, resp.Hero.Height)
 	})
 
+	t.Run("default hero episode", func(t *testing.T) {
+		var resp struct {
+			Hero struct {
+				Name string
+			}
+		}
+		c.MustPost(`{ hero { ... on Droid { name } } }`, &resp)
+
+		require.Equal(t, "R2-D2", resp.Hero.Name)
+	})
+
 	t.Run("friends", func(t *testing.T) {
 		var resp struct {
 			Human struct {