schema/field: add support for type-aware Default and UpdateDefault in time fields (#2289)

schema/field/field.go

@@ -369,8 +369,8 @@ func (b *timeBuilder) StructTag(s string) *timeBuilder {
 //	field.Time("created_at").
 //		Default(time.Now)
 //
-func (b *timeBuilder) Default(f func() time.Time) *timeBuilder {
-	b.desc.Default = f
+func (b *timeBuilder) Default(fn interface{}) *timeBuilder {
+	b.desc.Default = fn
 	return b
 }
 
@@ -381,8 +381,13 @@ func (b *timeBuilder) Default(f func() time.Time) *timeBuilder {
 //		Default(time.Now).
 //		UpdateDefault(time.Now),
 //
-func (b *timeBuilder) UpdateDefault(f func() time.Time) *timeBuilder {
-	b.desc.UpdateDefault = f
+//	field.Time("deleted_at").
+//		Optional().
+//		GoType(&sql.NullTime{}).
+//		UpdateDefault(NewNullTime),
+//
+func (b *timeBuilder) UpdateDefault(fn interface{}) *timeBuilder {
+	b.desc.UpdateDefault = fn
 	return b
 }
 
@@ -418,6 +423,9 @@ func (b *timeBuilder) Annotations(annotations ...schema.Annotation) *timeBuilder
 
 // Descriptor implements the ent.Field interface by returning its descriptor.
 func (b *timeBuilder) Descriptor() *Descriptor {
+	if b.desc.Default != nil {
+		b.desc.checkDefaultFunc(timeType)
+	}
 	return b.desc
 }
 

schema/field/field_test.go

@@ -407,7 +407,7 @@ func TestTime(t *testing.T) {
 	assert.Equal(t, now, fd.UpdateDefault.(func() time.Time)())
 
 	type Time time.Time
-	fd = field.Time("deleted_at").GoType(Time{}).Descriptor()
+	fd = field.Time("deleted_at").GoType(Time{}).Default(func() Time { return Time{} }).Descriptor()
 	assert.NoError(t, fd.Err)
 	assert.Equal(t, "field_test.Time", fd.Info.Ident)
 	assert.Equal(t, "entgo.io/ent/schema/field_test", fd.Info.PkgPath)
@@ -423,6 +423,8 @@ func TestTime(t *testing.T) {
 	assert.True(t, fd.Info.Nillable)
 	assert.True(t, fd.Info.ValueScanner())
 
+	fd = field.Time("deleted_at").GoType(Time{}).Default(time.Now).Descriptor()
+	assert.Error(t, fd.Err)
 	fd = field.Time("active").GoType(1).Descriptor()
 	assert.Error(t, fd.Err)
 	fd = field.Time("active").GoType(struct{}{}).Descriptor()