helper/schema: Allow identification of a new resource in update func

helper/schema/resource.go

@@ -142,6 +142,7 @@ func (r *Resource) Apply(
 	err = nil
 	if data.Id() == "" {
 		// We're creating, it is a new resource.
+		data.MarkNewResource()
 		err = r.Create(data, meta)
 	} else {
 		if r.Update == nil {

helper/schema/resource_data.go

@@ -30,6 +30,7 @@ type ResourceData struct {
 	partial     bool
 	partialMap  map[string]struct{}
 	once        sync.Once
+	isNew       bool
 }
 
 // getResult is the internal structure that is generated when a Get
@@ -171,6 +172,14 @@ func (d *ResourceData) SetPartial(k string) {
 	}
 }
 
+func (d *ResourceData) MarkNewResource() {
+	d.isNew = true
+}
+
+func (d *ResourceData) IsNewResource() bool {
+	return d.isNew
+}
+
 // Id returns the ID of the resource.
 func (d *ResourceData) Id() string {
 	var result string

helper/schema/resource_test.go

@@ -312,6 +312,87 @@ func TestResourceApply_updateNoCallback(t *testing.T) {
 	}
 }
 
+func TestResourceApply_isNewResource(t *testing.T) {
+	r := &Resource{
+		Schema: map[string]*Schema{
+			"foo": &Schema{
+				Type:     TypeString,
+				Optional: true,
+			},
+		},
+	}
+
+	updateFunc := func(d *ResourceData, m interface{}) error {
+		d.Set("foo", "updated")
+		if d.IsNewResource() {
+			d.Set("foo", "new-resource")
+		}
+		return nil
+	}
+	r.Create = func(d *ResourceData, m interface{}) error {
+		d.SetId("foo")
+		d.Set("foo", "created")
+		return updateFunc(d, m)
+	}
+	r.Update = updateFunc
+
+	d := &terraform.InstanceDiff{
+		Attributes: map[string]*terraform.ResourceAttrDiff{
+			"foo": &terraform.ResourceAttrDiff{
+				New: "bla-blah",
+			},
+		},
+	}
+
+	// positive test
+	var s *terraform.InstanceState = nil
+
+	actual, err := r.Apply(s, d, nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	expected := &terraform.InstanceState{
+		ID: "foo",
+		Attributes: map[string]string{
+			"id":  "foo",
+			"foo": "new-resource",
+		},
+	}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Fatalf("actual: %#v\nexpected: %#v",
+			actual, expected)
+	}
+
+	// negative test
+	s = &terraform.InstanceState{
+		ID: "foo",
+		Attributes: map[string]string{
+			"id":  "foo",
+			"foo": "new-resource",
+		},
+	}
+
+	actual, err = r.Apply(s, d, nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	expected = &terraform.InstanceState{
+		ID: "foo",
+		Attributes: map[string]string{
+			"id":  "foo",
+			"foo": "updated",
+		},
+	}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Fatalf("actual: %#v\nexpected: %#v",
+			actual, expected)
+	}
+}
+
 func TestResourceInternalValidate(t *testing.T) {
 	cases := []struct {
 		In  *Resource