Created
October 2, 2019 19:17
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IAsyncEnumerable ADO.NET Example
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| public static async IAsyncEnumerable<IEnumerable<object?>> GetResults(this SqlConnection connection, string query, [EnumeratorCancellation] CancellationToken token) | |
| { | |
| if (string.IsNullOrWhiteSpace(query)) | |
| { | |
| throw new ArgumentException(nameof(query)); | |
| } | |
| var wasClosed = connection.State != ConnectionState.Open; | |
| try | |
| { | |
| if (wasClosed) | |
| { | |
| await connection.OpenAsync(token); | |
| } | |
| using var command = new SqlCommand(query, connection); | |
| using var reader = await command.ExecuteReaderAsync(token); | |
| if (reader.HasRows) | |
| { | |
| while (!token.IsCancellationRequested && await reader.ReadAsync(token)) | |
| { | |
| var row = new List<object?>(reader.FieldCount); | |
| for (var i = 0; i < reader.FieldCount; i++) | |
| { | |
| var value = await reader.IsDBNullAsync(i) ? null : reader.GetValue(i); | |
| row.Add(value); | |
| } | |
| yield return row; | |
| } | |
| } | |
| } | |
| finally | |
| { | |
| if(wasClosed) | |
| { | |
| connection?.Close(); | |
| } | |
| } | |
| } |
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