schema/field: expose RType.Implements method (ent#2379)

Also, add both (T) and (*T) methods for RType

dialect/sql/schema/migrate.go

@@ -171,7 +171,7 @@ func (m *Migrate) Diff(ctx context.Context, tables ...*Table) error {
 	if err != nil {
 		return err
 	}
-	// Skip if the plan has no changes
+	// Skip if the plan has no changes.
 	if len(plan.Changes) == 0 {
 		return nil
 	}

schema/field/field.go

@@ -1165,37 +1165,43 @@ func (d *Descriptor) goType(typ interface{}, expectType reflect.Type) {
 			Methods: make(map[string]struct{ In, Out []*RType }, t.NumMethod()),
 		},
 	}
+	methods(t, info.RType)
 	switch t.Kind() {
 	case reflect.Slice, reflect.Ptr, reflect.Map:
 		info.Nillable = true
 	}
 	switch pt := reflect.PtrTo(t); {
-	case pt.Implements(valueScannerType):
-		t = pt
-		fallthrough
-	case t.Implements(valueScannerType):
-		n := t.NumMethod()
-		for i := 0; i < n; i++ {
-			m := t.Method(i)
-			in := make([]*RType, m.Type.NumIn()-1)
-			for j := range in {
-				arg := m.Type.In(j + 1)
-				in[j] = &RType{Name: arg.Name(), Ident: arg.String(), Kind: arg.Kind(), PkgPath: arg.PkgPath()}
-			}
-			out := make([]*RType, m.Type.NumOut())
-			for j := range out {
-				ret := m.Type.Out(j)
-				out[j] = &RType{Name: ret.Name(), Ident: ret.String(), Kind: ret.Kind(), PkgPath: ret.PkgPath()}
-			}
-			info.RType.Methods[m.Name] = struct{ In, Out []*RType }{in, out}
-		}
-	case t.Kind() == expectType.Kind() && t.ConvertibleTo(expectType):
+	case pt.Implements(valueScannerType), t.Implements(valueScannerType),
+		t.Kind() == expectType.Kind() && t.ConvertibleTo(expectType):
 	default:
 		d.Err = fmt.Errorf("GoType must be a %q type or ValueScanner", expectType)
 	}
 	d.Info = info
 }
 
+func methods(t reflect.Type, rtype *RType) {
+	// For type T, add methods with
+	// pointer receiver as well (*T).
+	if t.Kind() != reflect.Ptr {
+		t = reflect.PtrTo(t)
+	}
+	n := t.NumMethod()
+	for i := 0; i < n; i++ {
+		m := t.Method(i)
+		in := make([]*RType, m.Type.NumIn()-1)
+		for j := range in {
+			arg := m.Type.In(j + 1)
+			in[j] = &RType{Name: arg.Name(), Ident: arg.String(), Kind: arg.Kind(), PkgPath: arg.PkgPath()}
+		}
+		out := make([]*RType, m.Type.NumOut())
+		for j := range out {
+			ret := m.Type.Out(j)
+			out[j] = &RType{Name: ret.Name(), Ident: ret.String(), Kind: ret.Kind(), PkgPath: ret.PkgPath()}
+		}
+		rtype.Methods[m.Name] = struct{ In, Out []*RType }{in, out}
+	}
+}
+
 func (d *Descriptor) checkDefaultFunc(expectType reflect.Type) {
 	for _, typ := range []reflect.Type{reflect.TypeOf(d.Default), reflect.TypeOf(d.UpdateDefault)} {
 		if typ == nil || typ.Kind() != reflect.Func || d.Err != nil {

schema/field/field_test.go

@@ -8,14 +8,18 @@ import (
 	"database/sql"
 	"database/sql/driver"
 	"errors"
+	"fmt"
+	"io"
 	"net"
 	"net/http"
 	"net/url"
 	"reflect"
 	"regexp"
+	"strconv"
 	"testing"
 	"time"
 
+	"entgo.io/ent"
 	"entgo.io/ent/dialect"
 	"entgo.io/ent/schema/field"
 
@@ -680,6 +684,77 @@ func TestField_Other(t *testing.T) {
 	assert.Error(t, fd.Err, "invalid default value")
 }
 
+type UserRole string
+
+const (
+	Admin   UserRole = "ADMIN"
+	User    UserRole = "USER"
+	Unknown UserRole = "UNKNOWN"
+)
+
+func (UserRole) Values() (roles []string) {
+	for _, r := range []UserRole{Admin, User, Unknown} {
+		roles = append(roles, string(r))
+	}
+	return
+}
+
+func (e UserRole) String() string {
+	return string(e)
+}
+
+// MarshalGQL implements graphql.Marshaler interface.
+func (e UserRole) MarshalGQL(w io.Writer) {
+	_, _ = io.WriteString(w, strconv.Quote(e.String()))
+}
+
+// UnmarshalGQL implements graphql.Unmarshaler interface.
+func (e *UserRole) UnmarshalGQL(val interface{}) error {
+	str, ok := val.(string)
+	if !ok {
+		return fmt.Errorf("enum %T must be a string", val)
+	}
+	*e = UserRole(str)
+	switch *e {
+	case Admin, User, Unknown:
+		return nil
+	default:
+		return fmt.Errorf("%s is not a valid Role", str)
+	}
+}
+
+type Scalar struct{}
+
+func (Scalar) MarshalGQL(io.Writer)            {}
+func (*Scalar) UnmarshalGQL(interface{}) error { return nil }
+func (Scalar) Value() (driver.Value, error)    { return nil, nil }
+
+func TestRType_Implements(t *testing.T) {
+	type (
+		marshaler   interface{ MarshalGQL(w io.Writer) }
+		unmarshaler interface{ UnmarshalGQL(v interface{}) error }
+		codec       interface {
+			marshaler
+			unmarshaler
+		}
+	)
+	var (
+		codecType     = reflect.TypeOf((*codec)(nil)).Elem()
+		marshalType   = reflect.TypeOf((*marshaler)(nil)).Elem()
+		unmarshalType = reflect.TypeOf((*unmarshaler)(nil)).Elem()
+	)
+	for _, f := range []ent.Field{
+		field.Enum("role").GoType(Admin),
+		field.Other("scalar", &Scalar{}),
+		field.Other("scalar", Scalar{}),
+	} {
+		fd := f.Descriptor()
+		assert.True(t, fd.Info.RType.Implements(codecType))
+		assert.True(t, fd.Info.RType.Implements(marshalType))
+		assert.True(t, fd.Info.RType.Implements(unmarshalType))
+	}
+}
+
 func TestTypeString(t *testing.T) {
 	typ := field.TypeBool
 	assert.Equal(t, "bool", typ.String())

schema/field/type.go

@@ -120,12 +120,12 @@ func (t TypeInfo) ConstName() string {
 
 // ValueScanner indicates if this type implements the ValueScanner interface.
 func (t TypeInfo) ValueScanner() bool {
-	return t.RType.implements(valueScannerType)
+	return t.RType.Implements(valueScannerType)
 }
 
 // Valuer indicates if this type implements the driver.Valuer interface.
 func (t TypeInfo) Valuer() bool {
-	return t.RType.implements(valuerType)
+	return t.RType.Implements(valuerType)
 }
 
 // Comparable reports whether values of this type are comparable.
@@ -147,7 +147,7 @@ var stringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
 
 // Stringer indicates if this type implements the Stringer interface.
 func (t TypeInfo) Stringer() bool {
-	return t.RType.implements(stringerType)
+	return t.RType.Implements(stringerType)
 }
 
 var (
@@ -215,7 +215,8 @@ func (r *RType) IsPtr() bool {
 	return r != nil && r.Kind == reflect.Ptr
 }
 
-func (r *RType) implements(typ reflect.Type) bool {
+// Implements reports whether the RType ~implements the given interface type.
+func (r *RType) Implements(typ reflect.Type) bool {
 	if r == nil {
 		return false
 	}