SqlDataReader.GetFieldValueAsync<T>(Int32, CancellationToken) Method

Reference

Definition

Namespace:: System.Data.SqlClient

Assembly:: System.Data.SqlClient.dll

Assembly:: System.Data.dll

Package:: System.Data.SqlClient v4.9.0

Source:: System.Data.SqlClient.notsupported.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Asynchronously gets the value of the specified column as a type. GetFieldValue<T>(Int32) is the synchronous version of this method.

public:
generic <typename T>
 override System::Threading::Tasks::Task<T> ^ GetFieldValueAsync(int i, System::Threading::CancellationToken cancellationToken);

public override System.Threading.Tasks.Task<T> GetFieldValueAsync<T> (int i, System.Threading.CancellationToken cancellationToken);

override this.GetFieldValueAsync : int * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'T>

Public Overrides Function GetFieldValueAsync(Of T) (i As Integer, cancellationToken As CancellationToken) As Task(Of T)

Type Parameters

T

The type of the value to be returned.

Parameters

i: Int32

The column to be retrieved.

cancellationToken: CancellationToken

The cancellation instruction, which propagates a notification that operations should be canceled. This does not guarantee the cancellation. A setting of CancellationToken.None makes this method equivalent to IsDBNull(Int32). The returned task must be marked as cancelled.

Returns

Task<T>

The returned type object.

Exceptions

InvalidOperationException

The connection drops or is closed during the data retrieval.

The SqlDataReader is closed during the data retrieval.

There is no data ready to be read (for example, the first Read() hasn't been called, or returned false).

Tried to read a previously-read column in sequential mode.

There was an asynchronous operation in progress. This applies to all Get* methods when running in sequential mode, as they could be called while reading a stream.

Context Connection=true is specified in the connection string.

IndexOutOfRangeException

Trying to read a column that does not exist.

SqlNullValueException

The value of the column was null (IsDBNull(Int32) == true), retrieving a non-SQL type.

InvalidCastException

T doesn't match the type returned by SQL Server or cannot be cast.

OperationCanceledException

The cancellation token was canceled. This exception is stored into the returned task.

Remarks

T can be one of the following types:


Boolean	Byte	Char	DateTime
DateTimeOffset	Decimal	Double	Float
Guid	Int16	Int32	Int64
SqlBoolean	SqlByte	SqlDateTime	SqlDecimal
SqlDouble	SqlGuid	SqlInt16	SqlInt32
SqlInt64	SqlMoney	SqlSingle	SqlString
String	UDT, which can be any CLR type marked with SqlUserDefinedTypeAttribute.

For more information, see SqlClient Streaming Support.

Applies to

Κοινή χρήση μέσω