feat(bigquery): add rounding mode to FieldSchema (googleapis#10328)

Author: alvarowolfx

bigquery/schema.go

@@ -152,6 +152,11 @@ type FieldSchema struct {
 	// Information about the range.
 	// If the type is RANGE, this field is required.
 	RangeElementType *RangeElementType
+
+	// RoundingMode specifies the rounding mode to be used when storing
+	// values of NUMERIC and BIGNUMERIC type.
+	// If unspecified, default value is RoundHalfAwayFromZero.
+	RoundingMode RoundingMode
 }
 
 func (fs *FieldSchema) toBQ() *bq.TableFieldSchema {
@@ -166,6 +171,7 @@ func (fs *FieldSchema) toBQ() *bq.TableFieldSchema {
 		DefaultValueExpression: fs.DefaultValueExpression,
 		Collation:              string(fs.Collation),
 		RangeElementType:       fs.RangeElementType.toBQ(),
+		RoundingMode:           string(fs.RoundingMode),
 	}
 
 	if fs.Repeated {
@@ -253,6 +259,7 @@ func bqToFieldSchema(tfs *bq.TableFieldSchema) *FieldSchema {
 		DefaultValueExpression: tfs.DefaultValueExpression,
 		Collation:              tfs.Collation,
 		RangeElementType:       bqToRangeElementType(tfs.RangeElementType),
+		RoundingMode:           RoundingMode(tfs.RoundingMode),
 	}
 
 	for _, f := range tfs.Fields {
@@ -431,6 +438,21 @@ func InferSchema(st interface{}) (Schema, error) {
 	return inferSchemaReflectCached(reflect.TypeOf(st))
 }
 
+// RoundingMode  represents the rounding mode to be used when storing
+// values of NUMERIC and BIGNUMERIC type.
+type RoundingMode string
+
+const (
+	// RoundHalfAwayFromZero rounds half values away from zero when applying
+	// precision and scale upon writing of NUMERIC and BIGNUMERIC values.
+	// For Scale: 0 1.1, 1.2, 1.3, 1.4 => 1 1.5, 1.6, 1.7, 1.8, 1.9 => 2
+	RoundHalfAwayFromZero RoundingMode = "ROUND_HALF_AWAY_FROM_ZERO"
+	// RoundHalfEven rounds half values to the nearest even value when applying
+	// precision and scale upon writing of NUMERIC and BIGNUMERIC values.
+	// For Scale: 0 1.1, 1.2, 1.3, 1.4 => 1 1.5 => 2 1.6, 1.7, 1.8, 1.9 => 2 2.5 => 2
+	RoundHalfEven RoundingMode = "ROUND_HALF_EVEN"
+)
+
 var schemaCache sync.Map
 
 type cacheVal struct {

bigquery/schema_test.go

@@ -376,6 +376,34 @@ func TestSchemaConversion(t *testing.T) {
 				},
 			},
 		},
+		{
+			// rounding mode values
+			bqSchema: &bq.TableSchema{
+				Fields: []*bq.TableFieldSchema{
+					{
+						Name:         "num",
+						Type:         "NUMERIC",
+						RoundingMode: "ROUND_HALF_AWAY_FROM_ZERO",
+					},
+					{
+						Name:         "bignum",
+						Type:         "BIGNUMERIC",
+						RoundingMode: "ROUND_HALF_EVEN",
+					},
+				}},
+			schema: Schema{
+				{
+					Name:         "num",
+					Type:         NumericFieldType,
+					RoundingMode: RoundHalfAwayFromZero,
+				},
+				{
+					Name:         "bignum",
+					Type:         BigNumericFieldType,
+					RoundingMode: RoundHalfEven,
+				},
+			},
+		},
 		{
 			// policy tags
 			bqSchema: &bq.TableSchema{

bigquery/table_integration_test.go

@@ -696,6 +696,66 @@ func TestIntegration_TableDefaultCollation(t *testing.T) {
 	}
 }
 
+func TestIntegration_TableRoundingMode(t *testing.T) {
+	// Test RoundingMode for Table.Create and Table.Update
+	if client == nil {
+		t.Skip("Integration tests skipped")
+	}
+	ctx := context.Background()
+	table := dataset.Table(tableIDs.New())
+	schema := Schema{
+		{Name: "num", Type: NumericFieldType, RoundingMode: RoundHalfAwayFromZero},
+	}
+	err := table.Create(context.Background(), &TableMetadata{
+		Schema:         schema,
+		ExpirationTime: testTableExpiration,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer table.Delete(ctx)
+	md, err := table.Metadata(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// all fields should be RoundHalfAwayFromZero
+	for _, field := range md.Schema {
+		if field.RoundingMode != RoundHalfAwayFromZero {
+			t.Fatalf("expected to have rounding mode %q, but found %q on field: %v", RoundHalfAwayFromZero, field.RoundingMode, field.Name)
+		}
+	}
+
+	// Add a bignum field with different rounding mode
+	updatedSchema := md.Schema
+	updatedSchema = append(updatedSchema, &FieldSchema{
+		Name:         "bignum",
+		Type:         BigNumericFieldType,
+		RoundingMode: RoundHalfEven,
+	})
+	md, err = table.Update(ctx, TableMetadataToUpdate{
+		Schema: updatedSchema,
+	}, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// numeric field is RoundHalfAwayFromZero
+	// and bignum is RoundHalfEven
+	for _, field := range md.Schema {
+		if field.Type == NumericFieldType {
+			if field.RoundingMode != RoundHalfAwayFromZero {
+				t.Fatalf("expected to have rounding mode %q, but found %q on field: %v", RoundHalfAwayFromZero, field.RoundingMode, field.Name)
+			}
+		}
+		if field.Type == BigNumericFieldType {
+			if field.RoundingMode != RoundHalfEven {
+				t.Fatalf("expected to have rounding mode %q, but found %q on field: %v", RoundHalfEven, field.RoundingMode, field.Name)
+			}
+		}
+	}
+}
+
 func TestIntegration_TableConstraintsPK(t *testing.T) {
 	// Test Primary Keys for Table.Create and Table.Update
 	if client == nil {