feat(spanner): add metadata to RowIterator (#3050)
Adds ResultSetMetaData to the RowIterator struct. The metadata
are available after the first call to RowIterator.Next() as long
as that call did not return any other error than iterator.Done.
Fixes #1805
diff --git a/spanner/client_test.go b/spanner/client_test.go
index c30f39e..8750541 100644
--- a/spanner/client_test.go
+++ b/spanner/client_test.go
@@ -1880,6 +1880,51 @@
}
}
+func TestClient_ShouldReceiveMetadataForEmptyResultSet(t *testing.T) {
+ t.Parallel()
+
+ server, client, teardown := setupMockedTestServer(t)
+ // This creates an empty result set.
+ res := server.CreateSingleRowSingersResult(SelectSingerIDAlbumIDAlbumTitleFromAlbumsRowCount)
+ sql := "SELECT SingerId, AlbumId, AlbumTitle FROM Albums WHERE 1=2"
+ server.TestSpanner.PutStatementResult(sql, res)
+ defer teardown()
+ ctx := context.Background()
+ iter := client.Single().Query(ctx, NewStatement(sql))
+ defer iter.Stop()
+ row, err := iter.Next()
+ if err != iterator.Done {
+ t.Errorf("Query result mismatch:\nGot: %v\nWant: <no rows>", row)
+ }
+ metadata := iter.Metadata
+ if metadata == nil {
+ t.Fatalf("Missing ResultSet Metadata")
+ }
+ if metadata.RowType == nil {
+ t.Fatalf("Missing ResultSet RowType")
+ }
+ if metadata.RowType.Fields == nil {
+ t.Fatalf("Missing ResultSet Fields")
+ }
+ if g, w := len(metadata.RowType.Fields), 3; g != w {
+ t.Fatalf("Field count mismatch\nGot: %v\nWant: %v", g, w)
+ }
+ wantFieldNames := []string{"SingerId", "AlbumId", "AlbumTitle"}
+ for i, w := range wantFieldNames {
+ g := metadata.RowType.Fields[i].Name
+ if g != w {
+ t.Fatalf("Field[%v] name mismatch\nGot: %v\nWant: %v", i, g, w)
+ }
+ }
+ wantFieldTypes := []sppb.TypeCode{sppb.TypeCode_INT64, sppb.TypeCode_INT64, sppb.TypeCode_STRING}
+ for i, w := range wantFieldTypes {
+ g := metadata.RowType.Fields[i].Type.Code
+ if g != w {
+ t.Fatalf("Field[%v] type mismatch\nGot: %v\nWant: %v", i, g, w)
+ }
+ }
+}
+
func TestClient_EncodeCustomFieldType(t *testing.T) {
t.Parallel()
diff --git a/spanner/integration_test.go b/spanner/integration_test.go
index dd0a09c..47b266d 100644
--- a/spanner/integration_test.go
+++ b/spanner/integration_test.go
@@ -3156,6 +3156,11 @@
for {
row, err := iter.Next()
if err == iterator.Done {
+ if iter.Metadata == nil {
+ // All queries should always return metadata, regardless whether
+ // they return any rows or not.
+ return nil, errors.New("missing metadata from query")
+ }
return vals, nil
}
if err != nil {
diff --git a/spanner/internal/testutil/inmem_spanner_server.go b/spanner/internal/testutil/inmem_spanner_server.go
index 0735e09..fd39d74 100644
--- a/spanner/internal/testutil/inmem_spanner_server.go
+++ b/spanner/internal/testutil/inmem_spanner_server.go
@@ -148,6 +148,10 @@
break
}
}
+ } else {
+ result = append(result, &spannerpb.PartialResultSet{
+ Metadata: s.ResultSet.Metadata,
+ })
}
return result, nil
}
diff --git a/spanner/read.go b/spanner/read.go
index 268cf10..5ede3a3 100644
--- a/spanner/read.go
+++ b/spanner/read.go
@@ -102,6 +102,11 @@
// iterator.Done.
RowCount int64
+ // The metadata of the results of the query. The metadata are available
+ // after the first call to RowIterator.Next(), unless the first call to
+ // RowIterator.Next() returned an error that is not equal to iterator.Done.
+ Metadata *sppb.ResultSetMetadata
+
streamd *resumableStreamDecoder
rowd *partialResultSetDecoder
setTimestamp func(time.Time)
@@ -133,7 +138,11 @@
r.RowCount = rc
}
}
- r.rows, r.err = r.rowd.add(prs)
+ var metadata *sppb.ResultSetMetadata
+ r.rows, metadata, r.err = r.rowd.add(prs)
+ if metadata != nil {
+ r.Metadata = metadata
+ }
if r.err != nil {
return nil, r.err
}
@@ -648,7 +657,7 @@
// add tries to merge a new PartialResultSet into buffered Row. It returns any
// rows that have been completed as a result.
-func (p *partialResultSetDecoder) add(r *sppb.PartialResultSet) ([]*Row, error) {
+func (p *partialResultSetDecoder) add(r *sppb.PartialResultSet) ([]*Row, *sppb.ResultSetMetadata, error) {
var rows []*Row
if r.Metadata != nil {
// Metadata should only be returned in the first result.
@@ -663,20 +672,20 @@
}
}
if len(r.Values) == 0 {
- return nil, nil
+ return nil, r.Metadata, nil
}
if p.chunked {
p.chunked = false
// Try to merge first value in r.Values into uncompleted row.
last := len(p.row.vals) - 1
if last < 0 { // confidence check
- return nil, errChunkedEmptyRow()
+ return nil, nil, errChunkedEmptyRow()
}
var err error
// If p is chunked, then we should always try to merge p.last with
// r.first.
if p.row.vals[last], err = p.merge(p.row.vals[last], r.Values[0]); err != nil {
- return nil, err
+ return nil, r.Metadata, err
}
r.Values = r.Values[1:]
// Merge is done, try to yield a complete Row.
@@ -698,7 +707,7 @@
// also chunked.
p.chunked = true
}
- return rows, nil
+ return rows, r.Metadata, nil
}
// isMergeable returns if a protobuf Value can be potentially merged with other
diff --git a/spanner/read_test.go b/spanner/read_test.go
index 2b1ea48..87f6589 100644
--- a/spanner/read_test.go
+++ b/spanner/read_test.go
@@ -584,7 +584,7 @@
var rows []*Row
p := &partialResultSetDecoder{}
for j, v := range test.input {
- rs, err := p.add(v)
+ rs, _, err := p.add(v)
if err != nil {
t.Errorf("test %d.%d: partialResultSetDecoder.add(%v) = %v; want nil", i, j, v, err)
continue nextTest
