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NpgsqlDataReader.cs
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NpgsqlDataReader.cs
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#region License
// The PostgreSQL License
//
// Copyright (C) 2018 The Npgsql Development Team
//
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph and the following two paragraphs appear in all copies.
//
// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
#endregion
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Data;
using System.Data.Common;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using JetBrains.Annotations;
using Npgsql.BackendMessages;
using Npgsql.Logging;
using Npgsql.PostgresTypes;
using Npgsql.Schema;
using Npgsql.TypeHandlers;
using Npgsql.TypeHandling;
using NpgsqlTypes;
using static Npgsql.Statics;
#pragma warning disable CA2222 // Do not decrease inherited member visibility
namespace Npgsql
{
/// <summary>
/// Reads a forward-only stream of rows from a data source.
/// </summary>
#pragma warning disable CA1010
public abstract class NpgsqlDataReader : DbDataReader
#pragma warning restore CA1010
#if !NET45 && !NET451
, IDbColumnSchemaGenerator
#endif
{
internal NpgsqlCommand Command { get; private set; }
internal NpgsqlConnector Connector { get; }
NpgsqlConnection _connection;
/// <summary>
/// The behavior of the command with which this reader was executed.
/// </summary>
protected CommandBehavior Behavior;
Task _sendTask;
internal ReaderState State;
internal NpgsqlReadBuffer Buffer;
/// <summary>
/// Holds the list of statements being executed by this reader.
/// </summary>
List<NpgsqlStatement> _statements;
/// <summary>
/// The index of the current query resultset we're processing (within a multiquery)
/// </summary>
internal int StatementIndex { get; private set; }
/// <summary>
/// For streaming types (e.g. bytea), holds the byte length of the column.
/// Does not include the length prefix.
/// </summary>
internal int ColumnLen;
internal int PosInColumn;
int _charPos;
/// <summary>
/// The RowDescription message for the current resultset being processed
/// </summary>
[CanBeNull]
internal RowDescriptionMessage RowDescription;
uint? _recordsAffected;
/// <summary>
/// Whether the current result set has rows
/// </summary>
bool _hasRows;
/// <summary>
/// Is raised whenever Close() is called.
/// </summary>
public event EventHandler ReaderClosed;
bool IsSchemaOnly => (Behavior & CommandBehavior.SchemaOnly) != 0;
bool IsSequential => (Behavior & CommandBehavior.SequentialAccess) != 0;
/// <summary>
/// A stream that has been opened on a column.
/// </summary>
[CanBeNull]
private protected NpgsqlReadBuffer.ColumnStream ColumnStream;
/// <summary>
/// Used for internal temporary purposes
/// </summary>
[CanBeNull]
char[] _tempCharBuf;
static readonly NpgsqlLogger Log = NpgsqlLogManager.GetCurrentClassLogger();
internal NpgsqlDataReader(NpgsqlConnector connector)
{
Connector = connector;
}
internal void Init(NpgsqlCommand command, CommandBehavior behavior, List<NpgsqlStatement> statements, Task sendTask)
{
Command = command;
Debug.Assert(command.Connection == Connector.Connection);
_connection = command.Connection;
Behavior = behavior;
_statements = statements;
StatementIndex = -1;
_sendTask = sendTask;
State = ReaderState.BetweenResults;
_recordsAffected = null;
}
#region Read
/// <summary>
/// Advances the reader to the next record in a result set.
/// </summary>
/// <returns><b>true</b> if there are more rows; otherwise <b>false</b>.</returns>
/// <remarks>
/// The default position of a data reader is before the first record. Therefore, you must call Read to begin accessing data.
/// </remarks>
public override bool Read() => Read(false).GetAwaiter().GetResult();
/// <summary>
/// This is the asynchronous version of <see cref="Read()"/> The cancellation token is currently ignored.
/// </summary>
/// <param name="cancellationToken">Ignored for now.</param>
/// <returns>A task representing the asynchronous operation.</returns>
public override Task<bool> ReadAsync(CancellationToken cancellationToken)
{
using (NoSynchronizationContextScope.Enter())
return Read(true);
}
/// <summary>
/// Implementation of read
/// </summary>
Task<bool> Read(bool async)
{
// This is an optimized execution path that avoids calling any async methods for the (usual)
// case where the next row (or CommandComplete) is already in memory.
if ((Behavior & CommandBehavior.SingleRow) != 0)
return ReadLong();
switch (State)
{
case ReaderState.BeforeResult:
// First Read() after NextResult. Data row has already been processed.
State = ReaderState.InResult;
return PGUtil.TrueTask;
case ReaderState.InResult:
ConsumeRow(false);
break;
case ReaderState.BetweenResults:
case ReaderState.Consumed:
case ReaderState.Closed:
return PGUtil.FalseTask;
}
var readBuf = Connector.ReadBuffer;
if (readBuf.ReadBytesLeft < 5)
return ReadLong();
var messageCode = (BackendMessageCode)readBuf.ReadByte();
var len = readBuf.ReadInt32() - 4; // Transmitted length includes itself
if (messageCode != BackendMessageCode.DataRow || readBuf.ReadBytesLeft < len)
{
readBuf.ReadPosition -= 5;
return ReadLong();
}
var msg = Connector.ParseServerMessage(readBuf, messageCode, len, false);
ProcessMessage(msg);
return msg.Code == BackendMessageCode.DataRow
? PGUtil.TrueTask : PGUtil.FalseTask;
// If the above fast-path failed, we call into this async slow path
async Task<bool> ReadLong()
{
switch (State)
{
case ReaderState.BeforeResult:
// First Read() after NextResult. Data row has already been processed.
State = ReaderState.InResult;
return true;
case ReaderState.InResult:
await ConsumeRow(async);
if ((Behavior & CommandBehavior.SingleRow) != 0)
{
// TODO: See optimization proposal in #410
await Consume(async);
return false;
}
break;
case ReaderState.BetweenResults:
case ReaderState.Consumed:
case ReaderState.Closed:
return false;
default:
throw new ArgumentOutOfRangeException();
}
try
{
var msg2 = await ReadMessage(async);
ProcessMessage(msg2);
return msg2.Code == BackendMessageCode.DataRow;
}
catch (PostgresException)
{
State = ReaderState.Consumed;
throw;
}
}
}
internal void ProcessMessage(IBackendMessage msg)
{
Debug.Assert(msg != null);
switch (msg.Code)
{
case BackendMessageCode.DataRow:
Debug.Assert(RowDescription != null);
if (Connector.State != ConnectorState.Fetching)
Connector.State = ConnectorState.Fetching;
ProcessDataMessage((DataRowMessage)msg);
_hasRows = true;
switch (State)
{
case ReaderState.BetweenResults:
State = ReaderState.BeforeResult;
break;
case ReaderState.BeforeResult:
State = ReaderState.InResult;
break;
case ReaderState.InResult:
break;
default:
throw Connector.UnexpectedMessageReceived(BackendMessageCode.DataRow);
}
return;
case BackendMessageCode.CompletedResponse:
var completed = (CommandCompleteMessage) msg;
switch (completed.StatementType)
{
case StatementType.Update:
case StatementType.Insert:
case StatementType.Delete:
case StatementType.Copy:
case StatementType.Move:
if (!_recordsAffected.HasValue)
_recordsAffected = 0;
_recordsAffected += completed.Rows;
break;
}
_statements[StatementIndex].ApplyCommandComplete(completed);
goto case BackendMessageCode.EmptyQueryResponse;
case BackendMessageCode.EmptyQueryResponse:
State = ReaderState.BetweenResults;
return;
case BackendMessageCode.ReadyForQuery:
State = ReaderState.Consumed;
return;
default:
throw new Exception("Received unexpected backend message of type " + msg.Code);
}
}
internal abstract ValueTask<IBackendMessage> ReadMessage(bool async);
internal abstract void ProcessDataMessage(DataRowMessage dataMsg);
internal abstract Task SeekToColumn(int column, bool async);
internal abstract Task SeekInColumn(int posInColumn, bool async);
internal abstract Task ConsumeRow(bool async);
#endregion
#region NextResult
/// <summary>
/// Advances the reader to the next result when reading the results of a batch of statements.
/// </summary>
/// <returns></returns>
public sealed override bool NextResult()
{
try
{
return (IsSchemaOnly ? NextResultSchemaOnly(false) : NextResult(false))
.GetAwaiter().GetResult();
}
catch (PostgresException e)
{
State = ReaderState.Consumed;
if (StatementIndex >= 0 && StatementIndex < _statements.Count)
e.Statement = _statements[StatementIndex];
throw;
}
}
/// <summary>
/// This is the asynchronous version of NextResult.
/// The <paramref name="cancellationToken"/> parameter is currently ignored.
/// </summary>
/// <param name="cancellationToken">Currently ignored.</param>
/// <returns>A task representing the asynchronous operation.</returns>
public override Task<bool> NextResultAsync(CancellationToken cancellationToken)
{
try
{
using (NoSynchronizationContextScope.Enter())
return IsSchemaOnly ? NextResultSchemaOnly(true) : NextResult(true);
}
catch (PostgresException e)
{
State = ReaderState.Consumed;
if (StatementIndex >= 0 && StatementIndex < _statements.Count)
e.Statement = _statements[StatementIndex];
throw;
}
}
/// <summary>
/// Internal implementation of NextResult
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
async Task<bool> NextResult(bool async, bool isConsuming=false)
{
IBackendMessage msg;
Debug.Assert(!IsSchemaOnly);
// If we're in the middle of a resultset, consume it
switch (State)
{
case ReaderState.BeforeResult:
case ReaderState.InResult:
await ConsumeRow(async);
while (true)
{
var completedMsg = await Connector.ReadMessage(async, DataRowLoadingMode.Skip);
switch (completedMsg.Code)
{
case BackendMessageCode.CompletedResponse:
case BackendMessageCode.EmptyQueryResponse:
ProcessMessage(completedMsg);
break;
default:
continue;
}
break;
}
break;
case ReaderState.BetweenResults:
break;
case ReaderState.Consumed:
case ReaderState.Closed:
return false;
default:
throw new ArgumentOutOfRangeException();
}
Debug.Assert(State == ReaderState.BetweenResults);
_hasRows = false;
if ((Behavior & CommandBehavior.SingleResult) != 0 && StatementIndex == 0 && !isConsuming)
{
await Consume(async);
return false;
}
// We are now at the end of the previous result set. Read up to the next result set, if any.
// Non-prepared statements receive ParseComplete, BindComplete, DescriptionRow/NoData,
// prepared statements receive only BindComplete
for (StatementIndex++; StatementIndex < _statements.Count; StatementIndex++)
{
var statement = _statements[StatementIndex];
if (statement.IsPrepared)
{
Expect<BindCompleteMessage>(await Connector.ReadMessage(async));
RowDescription = statement.Description;
}
else // Non-prepared flow
{
var pStatement = statement.PreparedStatement;
if (pStatement != null)
{
Debug.Assert(!pStatement.IsPrepared);
Debug.Assert(pStatement.Description == null);
if (pStatement.StatementBeingReplaced != null)
{
Expect<CloseCompletedMessage>(await Connector.ReadMessage(async));
pStatement.StatementBeingReplaced.CompleteUnprepare();
pStatement.StatementBeingReplaced = null;
}
}
try
{
Expect<ParseCompleteMessage>(await Connector.ReadMessage(async));
}
catch
{
// An exception occurred. Check if any statements we being prepared and revert our bookkeeping.
pStatement?.CompleteUnprepare();
throw;
}
pStatement?.CompletePrepare();
Expect<BindCompleteMessage>(await Connector.ReadMessage(async));
msg = await Connector.ReadMessage(async);
switch (msg.Code)
{
case BackendMessageCode.NoData:
RowDescription = statement.Description = null;
break;
case BackendMessageCode.RowDescription:
// We have a resultset
RowDescription = statement.Description = (RowDescriptionMessage)msg;
break;
default:
throw Connector.UnexpectedMessageReceived(msg.Code);
}
}
// The following is a pretty awful hack to bring back output parameters for sequential readers (#2091)
// We should definitely clean up the entire reader design (#1853)
if (StatementIndex == 0 && RowDescription != null && Command.Parameters.HasOutputParameters)
{
// If output parameters are present and this is the first row of the first resultset,
// we must read it in non-sequential mode because it will be traversed twice (once
// here for the parameters, then as a regular row).
msg = await Connector.ReadMessage(async);
// If we got an actual first row (i.e. resultset wasn't empty), we process the message so it can
// be read by PopulateOutputParameters(). We then rewind the buffer to the start of the row, and
// continue to the normal flow, where we will process it again, as if we're reading a totally
// new row (using the same first row).
if (msg is DataRowMessage row)
{
var pos = Connector.ReadBuffer.ReadPosition;
ProcessMessage(row);
PopulateOutputParameters();
Connector.ReadBuffer.ReadPosition = pos;
State = ReaderState.BetweenResults;
}
}
else
msg = await ReadMessage(async);
if (RowDescription == null)
{
// Statement did not generate a resultset (e.g. INSERT)
// Read and process its completion message and move on to the next statement
switch (msg.Code)
{
case BackendMessageCode.CompletedResponse:
case BackendMessageCode.EmptyQueryResponse:
break;
default:
throw Connector.UnexpectedMessageReceived(msg.Code);
}
ProcessMessage(msg);
continue;
}
switch (msg.Code)
{
case BackendMessageCode.DataRow:
case BackendMessageCode.CompletedResponse:
break;
default:
throw Connector.UnexpectedMessageReceived(msg.Code);
}
ProcessMessage(msg);
return true;
}
// There are no more queries, we're done. Read to the RFQ.
ProcessMessage(Expect<ReadyForQueryMessage>(await Connector.ReadMessage(async)));
RowDescription = null;
return false;
}
void PopulateOutputParameters()
{
// The first row in a stored procedure command that has output parameters needs to be traversed twice -
// once for populating the output parameters and once for the actual result set traversal. So in this
// case we can't be sequential.
Debug.Assert(Command.Parameters.Any(p => p.IsOutputDirection));
Debug.Assert(StatementIndex == 0);
Debug.Assert(RowDescription != null);
Debug.Assert(State == ReaderState.BeforeResult);
// Temporarily set our state to InResult to allow us to read the values
State = ReaderState.InResult;
var pending = new Queue<object>();
var taken = new List<NpgsqlParameter>();
for (var i = 0; i < FieldCount; i++)
{
if (Command.Parameters.TryGetValue(GetName(i), out var p) && p.IsOutputDirection)
{
p.Value = GetValue(i);
taken.Add(p);
}
else
pending.Enqueue(GetValue(i));
}
// Not sure where this odd behavior comes from: all output parameters which did not get matched by
// name now get populated with column values which weren't matched. Keeping this for backwards compat,
// opened #2252 for investigation.
foreach (var p in Command.Parameters.Where(p => p.IsOutputDirection && !taken.Contains(p)))
{
if (pending.Count == 0)
break;
p.Value = pending.Dequeue();
}
State = ReaderState.BeforeResult; // Set the state back
}
/// <summary>
/// Note that in SchemaOnly mode there are no resultsets, and we read nothing from the backend (all
/// RowDescriptions have already been processed and are available)
/// </summary>
async Task<bool> NextResultSchemaOnly(bool async)
{
Debug.Assert(IsSchemaOnly);
for (StatementIndex++; StatementIndex < _statements.Count; StatementIndex++)
{
var statement = _statements[StatementIndex];
if (statement.IsPrepared)
{
// Row descriptions have already been populated in the statement objects at the
// Prepare phase
RowDescription = _statements[StatementIndex].Description;
}
else
{
Expect<ParseCompleteMessage>(await Connector.ReadMessage(async));
Expect<ParameterDescriptionMessage>(await Connector.ReadMessage(async));
var msg = await Connector.ReadMessage(async);
switch (msg.Code)
{
case BackendMessageCode.NoData:
RowDescription = _statements[StatementIndex].Description = null;
break;
case BackendMessageCode.RowDescription:
// We have a resultset
RowDescription = _statements[StatementIndex].Description = (RowDescriptionMessage)msg;
Command.FixupRowDescription(RowDescription, StatementIndex == 0);
break;
default:
throw Connector.UnexpectedMessageReceived(msg.Code);
}
}
// Found a resultset
if (RowDescription != null)
return true;
}
// There are no more queries, we're done. Read to the RFQ.
if (!_statements.All(s => s.IsPrepared))
{
ProcessMessage(Expect<ReadyForQueryMessage>(await Connector.ReadMessage(async)));
RowDescription = null;
}
return false;
}
#endregion
/// <summary>
/// Gets a value indicating the depth of nesting for the current row. Always returns zero.
/// </summary>
public override int Depth => 0;
/// <summary>
/// Gets a value indicating whether the data reader is closed.
/// </summary>
public override bool IsClosed => State == ReaderState.Closed;
/// <summary>
/// Gets the number of rows changed, inserted, or deleted by execution of the SQL statement.
/// </summary>
public override int RecordsAffected => _recordsAffected.HasValue ? (int)_recordsAffected.Value : -1;
/// <summary>
/// Returns details about each statement that this reader will or has executed.
/// </summary>
/// <remarks>
/// Note that some fields (i.e. rows and oid) are only populated as the reader
/// traverses the result.
///
/// For commands with multiple queries, this exposes the number of rows affected on
/// a statement-by-statement basis, unlike <see cref="NpgsqlDataReader.RecordsAffected"/>
/// which exposes an aggregation across all statements.
/// </remarks>
public IReadOnlyList<NpgsqlStatement> Statements => _statements.AsReadOnly();
/// <summary>
/// Gets a value that indicates whether this DbDataReader contains one or more rows.
/// </summary>
public override bool HasRows => State == ReaderState.Closed
? throw new InvalidOperationException("Invalid attempt to call HasRows when reader is closed.")
: _hasRows;
/// <summary>
/// Indicates whether the reader is currently positioned on a row, i.e. whether reading a
/// column is possible.
/// This property is different from <see cref="HasRows"/> in that <see cref="HasRows"/> will
/// return true even if attempting to read a column will fail, e.g. before <see cref="Read()"/>
/// has been called
/// </summary>
[PublicAPI]
public bool IsOnRow => State == ReaderState.InResult;
/// <summary>
/// Gets the name of the column, given the zero-based column ordinal.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The name of the specified column.</returns>
public override string GetName(int ordinal)
{
CheckResultSet();
CheckColumn(ordinal);
return RowDescription[ordinal].Name;
}
/// <summary>
/// Gets the number of columns in the current row.
/// </summary>
public override int FieldCount => RowDescription?.NumFields ?? 0;
#region Cleanup / Dispose
/// <summary>
/// Consumes all result sets for this reader, leaving the connector ready for sending and processing further
/// queries
/// </summary>
async Task Consume(bool async)
{
// Skip over the other result sets. Note that this does tally records affected
// from CommandComplete messages, and properly sets state for auto-prepared statements
if (IsSchemaOnly)
while (await NextResultSchemaOnly(async)) {}
else
while (await NextResult(async, true)) {}
}
/// <summary>
/// Releases the resources used by the <see cref="NpgsqlDataReader">NpgsqlDataReader</see>.
/// </summary>
protected override void Dispose(bool disposing) => Close();
/// <summary>
/// Closes the <see cref="NpgsqlDataReader"/> reader, allowing a new command to be executed.
/// </summary>
public override void Close() => Close(false, false).GetAwaiter().GetResult();
/// <summary>
/// Closes the <see cref="NpgsqlDataReader"/> reader, allowing a new command to be executed.
/// </summary>
public Task CloseAsync() => Close(false, true);
internal async Task Close(bool connectionClosing, bool async)
{
if (State == ReaderState.Closed)
return;
switch (Connector.State)
{
case ConnectorState.Broken:
case ConnectorState.Closed:
// This may have happen because an I/O error while reading a value, or some non-safe
// exception thrown from a type handler. Or if the connection was closed while the reader
// was still open
State = ReaderState.Closed;
Command.State = CommandState.Idle;
ReaderClosed?.Invoke(this, EventArgs.Empty);
return;
}
if (State != ReaderState.Consumed)
await Consume(async);
await Cleanup(async, connectionClosing);
}
internal async Task Cleanup(bool async, bool connectionClosing=false)
{
Log.Trace("Cleaning up reader", Connector.Id);
// Make sure the send task for this command, which may have executed asynchronously and in
// parallel with the reading, has completed, throwing any exceptions it generated.
if (async)
await _sendTask;
else
_sendTask.GetAwaiter().GetResult();
State = ReaderState.Closed;
Command.State = CommandState.Idle;
Connector.CurrentReader = null;
Connector.EndUserAction();
// If the reader is being closed as part of the connection closing, we don't apply
// the reader's CommandBehavior.CloseConnection
if ((Behavior & CommandBehavior.CloseConnection) != 0 && !connectionClosing)
_connection.Close();
if (ReaderClosed != null)
{
ReaderClosed(this, EventArgs.Empty);
ReaderClosed = null;
}
}
#endregion
#region Generic value getters
internal delegate T ReadDelegate<T>(NpgsqlReadBuffer buffer, int columnLen, FieldDescription fieldDescription);
internal delegate ValueTask<T> ReadAsyncDelegate<T>(NpgsqlReadBuffer buffer, int columnLen, bool async, FieldDescription fieldDescription);
internal static class NullableHandler<T>
{
public static readonly ReadDelegate<T> Read;
public static readonly ReadAsyncDelegate<T> ReadAsync;
public static readonly bool Exists;
static NullableHandler()
=> Exists = NullableHandler.Construct(out Read, out ReadAsync);
}
static class NullableHandler
{
static readonly MethodInfo _readNullableMethod = new ReadDelegate<int?>(ReadNullable<int>).Method.GetGenericMethodDefinition();
static readonly MethodInfo _readNullableAsyncMethod = new ReadAsyncDelegate<int?>(ReadNullable<int>).Method.GetGenericMethodDefinition();
static T? ReadNullable<T>(NpgsqlReadBuffer buffer, int columnLen, FieldDescription fieldDescription) where T : struct
=> fieldDescription.Handler.Read<T>(buffer, columnLen, fieldDescription);
static async ValueTask<T?> ReadNullable<T>(NpgsqlReadBuffer buffer, int columnLen, bool async, FieldDescription fieldDescription) where T : struct
=> await fieldDescription.Handler.Read<T>(buffer, columnLen, async, fieldDescription);
public static bool Construct<T>(out ReadDelegate<T> read, out ReadAsyncDelegate<T> readAsync)
{
var underlyingType = Nullable.GetUnderlyingType(typeof(T));
if (underlyingType != null)
{
read = (ReadDelegate<T>)_readNullableMethod.MakeGenericMethod(underlyingType).CreateDelegate(typeof(ReadDelegate<T>));
readAsync = (ReadAsyncDelegate<T>)_readNullableAsyncMethod.MakeGenericMethod(underlyingType).CreateDelegate(typeof(ReadAsyncDelegate<T>));
return true;
}
else
{
read = null;
readAsync = null;
return false;
}
}
}
#endregion Generic value getters
#region Simple value getters
/// <summary>
/// Gets the value of the specified column as a Boolean.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override bool GetBoolean(int ordinal) => GetFieldValue<bool>(ordinal);
/// <summary>
/// Gets the value of the specified column as a byte.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override byte GetByte(int ordinal) => GetFieldValue<byte>(ordinal);
/// <summary>
/// Gets the value of the specified column as a single character.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override char GetChar(int ordinal) => GetFieldValue<char>(ordinal);
/// <summary>
/// Gets the value of the specified column as a 16-bit signed integer.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override short GetInt16(int ordinal) => GetFieldValue<short>(ordinal);
/// <summary>
/// Gets the value of the specified column as a 32-bit signed integer.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override int GetInt32(int ordinal) => GetFieldValue<int>(ordinal);
/// <summary>
/// Gets the value of the specified column as a 64-bit signed integer.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override long GetInt64(int ordinal) => GetFieldValue<long>(ordinal);
/// <summary>
/// Gets the value of the specified column as a <see cref="DateTime"/> object.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override DateTime GetDateTime(int ordinal) => GetFieldValue<DateTime>(ordinal);
/// <summary>
/// Gets the value of the specified column as an instance of <see cref="string"/>.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override string GetString(int ordinal) => GetFieldValue<string>(ordinal);
/// <summary>
/// Gets the value of the specified column as a <see cref="decimal"/> object.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override decimal GetDecimal(int ordinal) => GetFieldValue<decimal>(ordinal);
/// <summary>
/// Gets the value of the specified column as a double-precision floating point number.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override double GetDouble(int ordinal) => GetFieldValue<double>(ordinal);
/// <summary>
/// Gets the value of the specified column as a single-precision floating point number.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override float GetFloat(int ordinal) => GetFieldValue<float>(ordinal);
/// <summary>
/// Gets the value of the specified column as a globally-unique identifier (GUID).
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override Guid GetGuid(int ordinal) => GetFieldValue<Guid>(ordinal);
/// <summary>
/// Populates an array of objects with the column values of the current row.
/// </summary>
/// <param name="values">An array of Object into which to copy the attribute columns.</param>
/// <returns>The number of instances of <see cref="object"/> in the array.</returns>
public override int GetValues(object[] values)
{
if (values == null)
throw new ArgumentNullException(nameof(values));
CheckRow();
var count = Math.Min(FieldCount, values.Length);
for (var i = 0; i < count; i++)
values[i] = GetValue(i);
return count;
}
/// <summary>
/// Gets the value of the specified column as an instance of <see cref="object"/>.
/// </summary>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public override object this[int ordinal] => GetValue(ordinal);
#endregion
#region Provider-specific type getters
/// <summary>
/// Gets the value of the specified column as an <see cref="NpgsqlDate"/>,
/// Npgsql's provider-specific type for dates.
/// </summary>
/// <remarks>
/// PostgreSQL's date type represents dates from 4713 BC to 5874897 AD, while .NET's DateTime
/// only supports years from 1 to 1999. If you require years outside this range use this accessor.
/// The standard <see cref="DbDataReader.GetProviderSpecificValue"/> method will also return this type, but has
/// the disadvantage of boxing the value.
/// See http://www.postgresql.org/docs/current/static/datatype-datetime.html
/// </remarks>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public NpgsqlDate GetDate(int ordinal) => GetFieldValue<NpgsqlDate>(ordinal);
/// <summary>
/// Gets the value of the specified column as a TimeSpan,
/// </summary>
/// <remarks>
/// PostgreSQL's interval type has has a resolution of 1 microsecond and ranges from
/// -178000000 to 178000000 years, while .NET's TimeSpan has a resolution of 100 nanoseconds
/// and ranges from roughly -29247 to 29247 years.
/// See http://www.postgresql.org/docs/current/static/datatype-datetime.html
/// </remarks>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public TimeSpan GetTimeSpan(int ordinal) => GetFieldValue<TimeSpan>(ordinal);
/// <summary>
/// Gets the value of the specified column as an <see cref="NpgsqlTimeSpan"/>,
/// Npgsql's provider-specific type for time spans.
/// </summary>
/// <remarks>
/// PostgreSQL's interval type has has a resolution of 1 microsecond and ranges from
/// -178000000 to 178000000 years, while .NET's TimeSpan has a resolution of 100 nanoseconds
/// and ranges from roughly -29247 to 29247 years. If you require values from outside TimeSpan's
/// range use this accessor.
/// The standard ADO.NET <see cref="DbDataReader.GetProviderSpecificValue"/> method will also return this
/// type, but has the disadvantage of boxing the value.
/// See http://www.postgresql.org/docs/current/static/datatype-datetime.html
/// </remarks>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public NpgsqlTimeSpan GetInterval(int ordinal) => GetFieldValue<NpgsqlTimeSpan>(ordinal);
/// <summary>
/// Gets the value of the specified column as an <see cref="NpgsqlDateTime"/>,
/// Npgsql's provider-specific type for date/time timestamps. Note that this type covers
/// both PostgreSQL's "timestamp with time zone" and "timestamp without time zone" types,
/// which differ only in how they are converted upon input/output.
/// </summary>
/// <remarks>
/// PostgreSQL's timestamp type represents dates from 4713 BC to 5874897 AD, while .NET's DateTime
/// only supports years from 1 to 1999. If you require years outside this range use this accessor.
/// The standard <see cref="DbDataReader.GetProviderSpecificValue"/> method will also return this type, but has
/// the disadvantage of boxing the value.
/// See http://www.postgresql.org/docs/current/static/datatype-datetime.html
/// </remarks>
/// <param name="ordinal">The zero-based column ordinal.</param>
/// <returns>The value of the specified column.</returns>
public NpgsqlDateTime GetTimeStamp(int ordinal) => GetFieldValue<NpgsqlDateTime>(ordinal);
#endregion
#region Special binary getters