Hi Wenyu , 

your expression needs to be corrected little 

Are you trying to compare between the object and the variable ?

If yes ,you did not used any object in the expression. 

Help me to understand your requirement , I can guide you through the right expression

• Retrieve Lists:

  • Retrieve: ReservationList (List of Reservation)
  • Retrieve: TableList (List of Table)

• Create Helper Entities:

  • Create: TableListHelper
  • Create: AvailableTableList (empty list of Table)

• Loop Through TableList:

  • Loop: TableList
    • Loop Variable: CurrentTable

• Inside Loop:

  • Decision: Check Availability
    • Expression:
      plaintext

      Code kopieren

      not(any($ReserveList[Table = $CurrentTable and StartTime <= $StartTime and EndTime >= $StartTime]))

• True Path of Decision:

  • Add to List: AvailableTableList
    • Action: Add CurrentTable

• After Loop:

  • Change Object: TableHelper
    • Association: $TableHelper/AvailableTables = $AvailableTableList
  • End: Return $TableHelper