private SpannerDbType GetSpannerFieldType(int i)
{
var fieldMetadata = PopulateMetadataAsync(CancellationToken.None).ResultWithUnwrappedExceptions().RowType
.Fields[i];
return(SpannerDbType.FromProtobufType(fieldMetadata.Type));
}
/// <inheritdoc />
public override System.Type GetFieldType(int i)
{
var fieldMetadata = PopulateMetadataAsync(CancellationToken.None).ResultWithUnwrappedExceptions().RowType
.Fields[i];
return(SpannerDbType.FromProtobufType(fieldMetadata.Type).DefaultClrType);
}
/// <summary>
/// When enabled, returns the schema of the query as a <see cref="DataTable"/>. This feature needs
/// to be enabled in the connection string via the <see cref="SpannerConnectionStringBuilder.EnableGetSchemaTable"/> property.
/// </summary>
/// <remarks>
/// <para>
/// <see cref="DbDataAdapter"/> will use this method automatically, but there is not enough information
/// available for it to do so to reliably manage data sets. This method returns <c>null</c> by default to
/// avoid this causing problems.
/// </para>
/// <para>
/// When the <c>EnableGetSchemaTable</c> property in the connection string is set to <c>true</c>, a
/// <c>DataTable</c> is returned with the following columns populated:
/// <list type="bullet">
/// <item><description>ColumnName (String): The name of the column</description></item>
/// <item><description>ColumnOrdinal (Int32): The ordinal value of the column</description></item>
/// <item><description>DataType (Type): The default CLR type of the column</description></item>
/// <item><description>ProviderType (SpannerDbType): The Spanner-specific data type of the column</description></item>
/// </list>
/// The following additional columns are present in the table, but not currently populated:
/// <list type="bullet">
/// <item><description>ColumnSize</description></item>
/// <item><description>NumericPrecision</description></item>
/// <item><description>NumericScale</description></item>
/// </list>
/// Future releases may expand the set of columns, or populate more of the existing columns.
/// </para>
/// </remarks>
/// <returns>A <c>DataTable</c> with schema information about the query, or <c>null</c> if the feature
/// is not enabled in the connection string.</returns>
public override DataTable GetSchemaTable()
{
// Spanner does not provide enough information for a schema table.
// DbDataAdapter will adjust and fill the dataset with information from
// this datareader (such as field type and name). By default, we just
// return null. The feature needs to be explicitly enabled in the connection string.
if (!_provideSchemaTable)
{
return(null);
}
var resultSet = PopulateMetadata();
// If the metadata couldn't be loaded, or there were no fields, just return null to indicate
// that the schema isn't available.
if ((resultSet?.RowType?.Fields?.Count ?? 0) == 0)
{
return(null);
}
var table = new DataTable("SchemaTable")
{
Columns =
{
{ "ColumnName", typeof(string) },
{ "ColumnOrdinal", typeof(int) },
{ "DataType", typeof(System.Type) },
{ "ProviderType", typeof(SpannerDbType) },
// Additional columns that are never populated.
{ "ColumnSize", typeof(int) },
{ "NumericPrecision", typeof(int) },
{ "NumericScale", typeof(int) }
}
};
int ordinal = 0;
foreach (var field in resultSet.RowType.Fields)
{
var row = table.NewRow();
SpannerDbType dbType = SpannerDbType.FromProtobufType(field.Type);
row["ColumnName"] = field.Name;
row["ColumnOrdinal"] = ordinal;
row["DataType"] = dbType.DefaultClrType;
row["ProviderType"] = dbType;
table.Rows.Add(row);
ordinal++;
}
return(table);
}
private SpannerDbType GetSpannerFieldType(int i)
{
var fieldMetadata = PopulateMetadata().RowType.Fields[i];
return(SpannerDbType.FromProtobufType(fieldMetadata.Type));
}
/// <inheritdoc />
public override System.Type GetFieldType(int i)
{
var fieldMetadata = PopulateMetadata().RowType.Fields[i];
return(SpannerDbType.FromProtobufType(fieldMetadata.Type).DefaultClrType);
}