feat(storage): add projection parameter for BucketHandle.Objects()

storage/bucket.go

@@ -1204,7 +1204,7 @@ func (it *ObjectIterator) Next() (*ObjectAttrs, error) {
 func (it *ObjectIterator) fetch(pageSize int, pageToken string) (string, error) {
 	req := it.bucket.c.raw.Objects.List(it.bucket.name)
 	setClientHeader(req.Header())
-	req.Projection("full")
+	req.Projection(it.query.GetProjection())
 	req.Delimiter(it.query.Delimiter)
 	req.Prefix(it.query.Prefix)
 	req.StartOffset(it.query.StartOffset)

storage/bucket_test.go

@@ -663,3 +663,31 @@ func TestNewBucket(t *testing.T) {
 		t.Errorf("got=-, want=+:\n%s", diff)
 	}
 }
+
+func TestObjectsWithProjection(t *testing.T) {
+	samples := []struct {
+		req, expect string
+	} {
+		{"", ProjectionFull},
+		{ProjectionFull, ProjectionFull},
+		{ProjectionNoAcl, ProjectionNoAcl},
+	}
+	res := &http.Response{StatusCode: http.StatusInternalServerError}
+	transport := &mockTransport{}
+	client := mockClient(t, transport)
+	bucket := client.Bucket("mock-bucket")
+	ctx := context.Background()
+
+	for _, sample := range samples {
+		transport.addResult(res, nil)
+		query := &Query{Projection: sample.req}
+		bucket.Objects(ctx, query).Next()
+
+		projection := transport.gotReq.URL.Query()["projection"]
+		if len(projection) == 0 {
+			t.Errorf("requesting %q projection: no projection parameter generated", sample.req)
+		} else if projection[0] != sample.expect {
+			t.Errorf("requesting %q projection: expecting %q, got %q", sample.req, sample.expect, projection[0])
+		}
+	}
+}

storage/storage.go

@@ -1306,6 +1306,14 @@ func encodeUint32(u uint32) string {
 	return base64.StdEncoding.EncodeToString(b)
 }
 
+const (
+	// ProjectionFull returns all fields of object(s).
+	ProjectionFull = "full"
+
+	// ProjectionNoAcl returns all fields of object(s) except for owner and acl.
+	ProjectionNoAcl = "noAcl"
+)
+
 // Query represents a query to filter objects from a bucket.
 type Query struct {
 	// Delimiter returns results in a directory-like fashion.
@@ -1341,6 +1349,10 @@ type Query struct {
 	// lexicographically before endOffset. If startOffset is also set, the objects
 	// listed will have names between startOffset (inclusive) and endOffset (exclusive).
 	EndOffset string
+
+	// Projection defines set of properties to return. This may be either
+	// ProjectionFull or ProjectionNoAcl, zero value means ProjectionFull.
+	Projection string
 }
 
 // attrToFieldMap maps the field names of ObjectAttrs to the underlying field
@@ -1411,6 +1423,16 @@ func (q *Query) SetAttrSelection(attrs []string) error {
 	return nil
 }
 
+// GetProjection returns either value of Projection field or
+// default projection when this field is empty.
+func (q *Query) GetProjection() string {
+	if q.Projection == "" {
+		return ProjectionFull
+	} else {
+		return q.Projection
+	}
+}
+
 // Conditions constrain methods to act on specific generations of
 // objects.
 //