/// <summary>
/// Gets the expression.
/// </summary>
/// <param name="context">The context.</param>
/// <param name="entityIdProperty">The entity identifier property.</param>
/// <param name="selection">The selection.</param>
/// <returns></returns>
public override System.Linq.Expressions.Expression GetExpression(Rock.Data.RockContext context, System.Linq.Expressions.MemberExpression entityIdProperty, string selection)
{
var attributeValueService = new AttributeValueService(context);
var roomReservationGroupAttGuid = ZoomGuid.Attribute.ROOM_RESERVATION_GROUP_ATTRIBUTE.AsGuid();
var reservationLocationEntityTypeId = new EntityTypeService(context).GetNoTracking(com.bemaservices.RoomManagement.SystemGuid.EntityType.RESERVATION_LOCATION.AsGuid()).Id;
var resGroupAttValues = attributeValueService.Queryable()
.Where(x => x.Attribute.Guid == roomReservationGroupAttGuid)
.Select(x => new { EntityId = x.EntityId, Value = x.Value });
var groupQuery = new GroupService(context).Queryable()
.Select(g => new { GuidString = g.Guid.ToString(), GroupName = g.Name + " (" + g.Id.ToString() + ")" });
var reservationQuery = new ReservationService(context).Queryable()
.Select(r => new { r.Id });
var reservationlocationQuery = new ReservationLocationService(context).Queryable()
.Select(rl => new { rl.Id, rl.ReservationId });
var occurrenceService = new RoomOccurrenceService(context);
var resultQuery = occurrenceService.Queryable("ReservationLocation")
.Select(ro => groupQuery.FirstOrDefault(g => resGroupAttValues.FirstOrDefault(v => reservationQuery.FirstOrDefault(r => reservationlocationQuery.FirstOrDefault(rl => ro.EntityTypeId == reservationLocationEntityTypeId && rl.Id == ro.EntityId).ReservationId == r.Id).Id == v.EntityId).Value.Contains(g.GuidString)).GroupName);
return(SelectExpressionExtractor.Extract(resultQuery, entityIdProperty, "ro"));
}