Merge pull request #335 from 99designs/typed-interfaces

Generate typed interfaces for gql interfaces & unions

codegen/interface_build.go

@@ -1,9 +1,7 @@
 package codegen
 
 import (
-	"fmt"
 	"go/types"
-	"os"
 	"sort"
 
 	"github.com/vektah/gqlparser/ast"
@@ -51,20 +49,5 @@ func (cfg *Config) isValueReceiver(intf *NamedType, implementor *NamedType, prog
 		return true
 	}
 
-	for i := 0; i < interfaceType.NumMethods(); i++ {
-		intfMethod := interfaceType.Method(i)
-
-		implMethod := findMethod(implementorType, intfMethod.Name())
-		if implMethod == nil {
-			fmt.Fprintf(os.Stderr, "missing method %s on %s\n", intfMethod.Name(), implementor.GoType)
-			return false
-		}
-
-		sig := implMethod.Type().(*types.Signature)
-		if _, isPtr := sig.Recv().Type().(*types.Pointer); isPtr {
-			return false
-		}
-	}
-
-	return true
+	return types.Implements(implementorType, interfaceType)
 }

codegen/model.go

@@ -4,6 +4,7 @@ type Model struct {
 	*NamedType
 	Description string
 	Fields      []ModelField
+	Implements  []*NamedType
 }
 
 type ModelField struct {

codegen/models_build.go

@@ -54,8 +54,9 @@ func (cfg *Config) buildModels(types NamedTypes, prog *loader.Program, imports *
 
 func (cfg *Config) obj2Model(obj *Object) Model {
 	model := Model{
-		NamedType: obj.NamedType,
-		Fields:    []ModelField{},
+		NamedType:  obj.NamedType,
+		Implements: obj.Implements,
+		Fields:     []ModelField{},
 	}
 
 	model.GoType = ucFirst(obj.GQLType)

codegen/object.go

@@ -24,6 +24,7 @@ type Object struct {
 
 	Fields             []Field
 	Satisfies          []string
+	Implements         []*NamedType
 	ResolverInterface  *Ref
 	Root               bool
 	DisableConcurrency bool

codegen/object_build.go

@@ -104,6 +104,10 @@ func (cfg *Config) buildObject(types NamedTypes, typ *ast.Definition, imports *I
 
 	obj.Satisfies = append(obj.Satisfies, typ.Interfaces...)
 
+	for _, intf := range cfg.schema.GetImplements(typ) {
+		obj.Implements = append(obj.Implements, types[intf.Name])
+	}
+
 	for _, field := range typ.Fields {
 		if typ == cfg.schema.Query && field.Name == "__type" {
 			obj.Fields = append(obj.Fields, Field{

codegen/templates/models.gotpl

@@ -11,7 +11,9 @@ import (
 {{ range $model := .Models }}
 	{{with .Description}} {{.|prefixLines "// "}} {{end}}
 	{{- if .IsInterface }}
-		type {{.GoType}} interface {}
+		type {{.GoType}} interface {
+			Is{{.GoType}}()
+		}
 	{{- else }}
 		type {{.GoType}} struct {
 			{{- range $field := .Fields }}
@@ -25,6 +27,11 @@ import (
 				{{- end }}
 			{{- end }}
 		}
+
+		{{- range $iface := .Implements }}
+			func ({{$model.GoType}}) Is{{$iface.GoType}}() {}
+		{{- end }}
+
 	{{- end }}
 {{- end}}
 

codegen/testserver/interfaces.go

@@ -4,10 +4,12 @@ import "math"
 
 type Shape interface {
 	Area() float64
+	isShape()
 }
 
 type ShapeUnion interface {
 	Area() float64
+	isShapeUnion()
 }
 
 type Circle struct {
@@ -18,10 +20,15 @@ func (c *Circle) Area() float64 {
 	return c.Radius * math.Pi * math.Pi
 }
 
+func (c *Circle) isShapeUnion() {}
+func (c *Circle) isShape()      {}
+
 type Rectangle struct {
 	Length, Width float64
 }
 
 func (r *Rectangle) Area() float64 {
 	return r.Length * r.Width
 }
+func (r *Rectangle) isShapeUnion() {}
+func (r *Rectangle) isShape()      {}

example/starwars/model.go

@@ -34,6 +34,9 @@ func (h *Human) Height(unit LengthUnit) float64 {
 	}
 }
 
+func (Human) IsCharacter()    {}
+func (Human) IsSearchResult() {}
+
 type Review struct {
 	Stars      int
 	Commentary *string
@@ -45,6 +48,9 @@ type Droid struct {
 	PrimaryFunction string
 }
 
+func (Droid) IsCharacter()    {}
+func (Droid) IsSearchResult() {}
+
 func (r *Resolver) resolveFriendConnection(ctx context.Context, ids []string, first *int, after *string) (FriendsConnection, error) {
 	from := 0
 	if after != nil {