Package org.openhab.core.persistence

Interface QueryablePersistenceService

All Superinterfaces:
PersistenceService
All Known Subinterfaces:
ModifiablePersistenceService
@NonNullByDefault public interface QueryablePersistenceService extends PersistenceService
A queryable persistence service which can be used to store and retrieve data from openHAB. This is most likely some kind of database system.
Author:
Kai Kreuzer - Initial contribution, Chris Jackson - Added getItems method, Mark Herwege - Added methods to retrieve lastUpdate, lastChange and lastState from persistence, Mark Herwege - Implement aliases

  • Method Details

    • query

      Iterable<HistoricItem> query(FilterCriteria filter)
      Queries the PersistenceService for historic data with a given FilterCriteria. If the persistence service implementing this class supports using aliases for item names, the default implementation of query(FilterCriteria, String) should be overridden as well.
      Parameters:
      filter - the filter to apply to the query
      Returns:
      a time series of items

    • query

      default Iterable<HistoricItem> query(FilterCriteria filter, @Nullable String alias)
      Queries the PersistenceService for historic data with a given FilterCriteria. If the persistence service implementing this interface supports aliases and relies on item registry lookups, the default implementation should be overridden to query the database with the aliased name.
      Parameters:
      filter - the filter to apply to the query
      alias - for item name in database
      Returns:
      a time series of items

    • getItemInfo

      default Set<PersistenceItemInfo> getItemInfo() throws UnsupportedOperationException
      Returns a set of PersistenceItemInfo about items that are stored in the persistence service. This allows the persistence service to return information about items that are no longer available as an Item in openHAB. If it is not possible to retrieve the information or it would be too expensive to do so an UnsupportedOperationException should be thrown. Note that this method will return the names for items as stored in persistence. If aliases are used, the calling method is responsible for mapping back to the real item name.
      Returns:
      a set of information about the persisted items
      Throws:
      UnsupportedOperationException - if the operation is not supported or would be too expensive to perform

    • getItemInfo

      default @Nullable PersistenceItemInfo getItemInfo(String itemName, @Nullable String alias) throws UnsupportedOperationException
      Returns PersistenceItemInfo for an item stored in the persistence service. Null can be returned when the item is not found in the persistence service. If it is not possible to retrieve the information or it would be too expensive to do so an UnsupportedOperationException should be thrown. The default implementation will query the persistence service for the last value in the persistence store and set the latest timestamp, leaving the PersistenceItemInfo earliest timestamp and count equal to null. Note that the method should return the alias for the item in its response if an alias is being used.
      Parameters:
      itemName - the real openHAB name as it appears in the item registry
      alias - for item name in database or null if no alias defined
      Returns:
      information about the persisted item
      Throws:
      UnsupportedOperationException - if the operation is not supported or would be too expensive to perform

    • persistedItem

      default @Nullable PersistedItem persistedItem(String itemName, @Nullable String alias)
      Returns a PersistedItem representing the persisted state, last update and change timestamps and previous persisted state. This can be used to restore the full state of an item. The default implementation only queries the service for the last persisted state and does not attempt to look further back to find the last change timestamp and previous persisted state. This avoids potential performance issues if this method is not overriden in the specific persistence service. Persistence services should override this default implementation with a more complete and efficient algorithm.
      Parameters:
      itemName - name of item
      alias - alias of item
      Returns:
      a PersistedItem or null if the item has not been persisted