/// <summary>
/// Initiates an asynchronous get of the binary file specified by fileId or fileGuid
/// Intended to be used by an IHttpAsyncHandler
/// </summary>
/// <param name="callback">The callback.</param>
/// <param name="context">The context.</param>
/// <param name="fileGuid">The file unique identifier.</param>
/// <param name="fileId">The file identifier.</param>
/// <returns></returns>
private IAsyncResult BeginGet(AsyncCallback callback, HttpContext context, Guid fileGuid, int?fileId)
{
SqlConnection conn = new SqlConnection(string.Format("{0};Asynchronous Processing=true;", ConfigurationManager.ConnectionStrings["RockContext"].ConnectionString));
conn.Open();
SqlCommand cmd = conn.CreateCommand();
cmd.CommandText = "spCore_BinaryFileGet";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new SqlParameter("@Id", fileId.HasValue ? fileId.Value : 0));
cmd.Parameters.Add(new SqlParameter("@Guid", fileGuid));
// store our Command to be later retrieved by EndGet
context.AddOrReplaceItem("Rock.Model.BinaryFileService:SqlCommand", cmd);
// start async DB read
return(cmd.BeginExecuteReader(
callback,
context,
CommandBehavior.SequentialAccess | // doesn't load whole column into memory
CommandBehavior.SingleRow | // performance improve since we only want one row
CommandBehavior.CloseConnection)); // close connection immediately after read
}