Class DataContext

java.lang.Object
org.apache.cayenne.BaseContext
org.apache.cayenne.access.DataContext
All Implemented Interfaces:
Serializable, DataChannel, ObjectContext

public class DataContext
extends BaseContext
The most common implementation of ObjectContext. DataContext is an isolated container of an object graph, in a sense that any uncommitted changes to persistent objects that are registered with the context, are not visible to the users of other contexts.
See Also:
Serialized Form
  • Field Details

    • usingSharedSnaphsotCache

      protected boolean usingSharedSnaphsotCache
    • objectStore

      protected ObjectStore objectStore
    • transactionFactory

      @Deprecated protected transient TransactionFactory transactionFactory
      Deprecated.
      since 4.0 used in a method that itself should be deprecated, so this is a temp code
    • mergeHandler

      protected transient org.apache.cayenne.access.DataContextMergeHandler mergeHandler
  • Constructor Details

    • DataContext

      public DataContext()
      Creates a new DataContext that is not attached to the Cayenne stack.
    • DataContext

      public DataContext​(DataChannel channel, ObjectStore objectStore)
      Creates a new DataContext with parent DataChannel and ObjectStore.
      Since:
      1.2
  • Method Details

    • attachToRuntime

      protected void attachToRuntime​(Injector injector)
      Description copied from class: BaseContext
      Attaches this context to the CayenneRuntime whose Injector is passed as an argument to this method.
      Overrides:
      attachToRuntime in class BaseContext
    • attachToChannel

      protected void attachToChannel​(DataChannel channel)
      Description copied from class: BaseContext
      Attaches to a provided DataChannel.
      Overrides:
      attachToChannel in class BaseContext
      Since:
      3.1
    • getParentDataDomain

      public DataDomain getParentDataDomain()
      Returns a DataDomain used by this DataContext. DataDomain is looked up in the DataChannel hierarchy. If a channel is not a DataDomain or a DataContext, null is returned.
      Returns:
      DataDomain that is a direct or indirect parent of this DataContext in the DataChannel hierarchy.
      Since:
      1.1
    • setDelegate

      public void setDelegate​(DataContextDelegate delegate)
      Sets a DataContextDelegate for this context. Delegate is notified of certain events in the DataContext lifecycle and can customize DataContext behavior.
      Since:
      1.1
    • getDelegate

      public DataContextDelegate getDelegate()
      Returns a delegate currently associated with this DataContext.
      Since:
      1.1
    • getObjectStore

      public ObjectStore getObjectStore()
      Returns ObjectStore associated with this DataContext.
    • hasChanges

      public boolean hasChanges()
      Returns true if there are any modified, deleted or new objects registered with this DataContext, false otherwise.
    • newObjects

      public Collection<?> newObjects()
      Returns a list of objects that are registered with this DataContext and have a state PersistenceState.NEW
      Specified by:
      newObjects in interface ObjectContext
      Specified by:
      newObjects in class BaseContext
    • deletedObjects

      public Collection<?> deletedObjects()
      Returns a list of objects that are registered with this DataContext and have a state PersistenceState.DELETED
      Specified by:
      deletedObjects in interface ObjectContext
      Specified by:
      deletedObjects in class BaseContext
    • modifiedObjects

      public Collection<?> modifiedObjects()
      Returns a list of objects that are registered with this DataContext and have a state PersistenceState.MODIFIED
      Specified by:
      modifiedObjects in interface ObjectContext
      Specified by:
      modifiedObjects in class BaseContext
    • uncommittedObjects

      public Collection<?> uncommittedObjects()
      Returns a collection of all uncommitted registered objects.
      Specified by:
      uncommittedObjects in interface ObjectContext
      Specified by:
      uncommittedObjects in class BaseContext
      Since:
      1.2
    • currentSnapshot

      public DataRow currentSnapshot​(Persistent object)
      Returns a DataRow reflecting current, possibly uncommitted, object state.

      Warning: This method will return a partial snapshot if an object or one of its related objects that propagate their keys to this object have temporary ids. DO NOT USE this method if you expect a DataRow to represent a complete object state.

      Since:
      1.1
    • objectsFromDataRows

      public List objectsFromDataRows​(ClassDescriptor descriptor, List<? extends DataRow> dataRows)
      Converts a list of DataRows to a List of DataObject registered with this DataContext.
      Since:
      3.0
    • objectFromDataRow

      public <T extends Persistent> T objectFromDataRow​(Class<T> objectClass, DataRow dataRow)
      Creates a DataObject from DataRow.
      Since:
      3.1
      See Also:
      DataRow
    • objectFromDataRow

      public DataObject objectFromDataRow​(String entityName, DataRow dataRow)
      Creates a DataObject from DataRow. This variety of the 'objectFromDataRow' method is normally used for generic classes.
      Since:
      3.1
      See Also:
      DataRow
    • newObject

      public <T> T newObject​(Class<T> persistentClass)
      Creates and registers a new persistent object.
      Specified by:
      newObject in interface ObjectContext
      Specified by:
      newObject in class BaseContext
      Since:
      1.2
    • newObject

      public Persistent newObject​(String entityName)
      Instantiates a new object and registers it with this context. Object class is determined from the mapped entity. Object class must have a default constructor.

      Note: in most cases newObject(Class) method should be used, however this method is helpful when generic persistent classes are used.

      Since:
      3.0
    • registerNewObject

      public void registerNewObject​(Object object)
      Registers a transient object with the context, recursively registering all transient persistent objects attached to this object via relationships.

      Note that since 3.0 this method takes Object as an argument instead of a DataObject.

      Specified by:
      registerNewObject in interface ObjectContext
      Specified by:
      registerNewObject in class BaseContext
      Parameters:
      object - new object that needs to be made persistent.
    • unregisterObjects

      public void unregisterObjects​(Collection dataObjects)
      Unregisters a Collection of DataObjects from the DataContext and the underlying ObjectStore. This operation also unsets DataContext for each object and changes its state to TRANSIENT.
      See Also:
      BaseContext.invalidateObjects(Collection)
    • rollbackChangesLocally

      public void rollbackChangesLocally()
      If the parent channel is a DataContext, reverts local changes to make this context look like the parent, if the parent channel is a DataDomain, reverts all changes.
      Specified by:
      rollbackChangesLocally in interface ObjectContext
      Specified by:
      rollbackChangesLocally in class BaseContext
      Since:
      1.2
    • rollbackChanges

      public void rollbackChanges()
      Reverts any changes that have occurred to objects registered with DataContext; also performs cascading rollback of all parent DataContexts.
      Specified by:
      rollbackChanges in interface ObjectContext
      Specified by:
      rollbackChanges in class BaseContext
    • commitChangesToParent

      public void commitChangesToParent()
      "Flushes" the changes to the parent DataChannel. If the parent channel is a DataContext, it updates its objects with this context's changes, without a database update. If it is a DataDomain (the most common case), the changes are written to the database. To cause cascading commit all the way to the database, one must use commitChanges() .
      Specified by:
      commitChangesToParent in interface ObjectContext
      Specified by:
      commitChangesToParent in class BaseContext
      Since:
      1.2
      See Also:
      commitChanges()
    • commitChanges

      public void commitChanges() throws CayenneRuntimeException
      Synchronizes object graph with the database. Executes needed insert, update and delete queries (generated internally).
      Specified by:
      commitChanges in interface ObjectContext
      Specified by:
      commitChanges in class BaseContext
      Throws:
      CayenneRuntimeException
    • onContextFlush

      protected GraphDiff onContextFlush​(ObjectContext originatingContext, GraphDiff changes, boolean cascade)
      Specified by:
      onContextFlush in class BaseContext
    • iterator

      public <T> ResultIterator<T> iterator​(Select<T> query)
      Description copied from interface: ObjectContext
      Creates a ResultIterator based on the provided query. It is usually backed by an open result set and is useful for processing of large data sets, preserving a constant memory footprint. The caller must wrap iteration in try/finally (or try-with-resources for Java 1.7 and higher) and close the ResultIterator explicitly. Or use ObjectContext.iterate(Select, ResultIteratorCallback) as an alternative.
      Specified by:
      iterator in interface ObjectContext
      Specified by:
      iterator in class BaseContext
    • performIteratedQuery

      public ResultIterator performIteratedQuery​(Query query)
      Performs a single database select query returning result as a ResultIterator. It is caller's responsibility to explicitly close the ResultIterator. A failure to do so will result in a database connection not being released. Another side effect of an open ResultIterator is that an internal Cayenne transaction that originated in this method stays open until the iterator is closed. So users should normally close the iterator within the same thread that opened it.

      Note that 'performIteratedQuery' always returns ResultIterator over DataRows. Use BaseContext.iterate(Select, org.apache.cayenne.ResultIteratorCallback) to get access to objects.

    • performGenericQuery

      public QueryResponse performGenericQuery​(Query query)
      Executes a query returning a generic response.
      Specified by:
      performGenericQuery in interface ObjectContext
      Specified by:
      performGenericQuery in class BaseContext
      Since:
      1.2
    • performQuery

      public List performQuery​(Query query)
      Performs a single selecting query. Various query setting control the behavior of this method and the results returned:
      • Query caching policy defines whether the results are retrieved from cache or fetched from the database. Note that queries that use caching must have a name that is used as a caching key.
      • Query refreshing policy controls whether to refresh existing data objects and ignore any cached values.
      • Query data rows policy defines whether the result should be returned as DataObjects or DataRows.

      Since 1.2 takes any Query parameter, not just GenericSelectQuery

      Specified by:
      performQuery in interface ObjectContext
      Specified by:
      performQuery in class BaseContext
      Returns:
      A list of DataObjects or a DataRows, depending on the value returned by QueryMetadata.isFetchingDataRows().
    • onQuery

      public QueryResponse onQuery​(ObjectContext context, Query query)
      An implementation of a DataChannel method that is used by child contexts to execute queries. Not intended for direct use.
      Parameters:
      context - an ObjectContext that originated the query, used to register result objects.
      Returns:
      a generic response object that encapsulates result of the execution.
      Since:
      1.2
    • performNonSelectingQuery

      public int[] performNonSelectingQuery​(Query query)
      Performs a single database query that does not select rows. Returns an array of update counts.
      Since:
      1.1
    • performNonSelectingQuery

      public int[] performNonSelectingQuery​(String queryName)
      Performs a named mapped query that does not select rows. Returns an array of update counts.
      Since:
      1.1
    • performNonSelectingQuery

      public int[] performNonSelectingQuery​(String queryName, Map<String,​?> parameters)
      Performs a named mapped non-selecting query using a map of parameters. Returns an array of update counts.
      Since:
      1.1
    • performQuery

      public List<?> performQuery​(String queryName, boolean expireCachedLists)
      Returns a list of objects or DataRows for a named query stored in one of the DataMaps. Internally Cayenne uses a caching policy defined in the named query. If refresh flag is true, a refresh is forced no matter what the caching policy is.
      Parameters:
      queryName - a name of a GenericSelectQuery defined in one of the DataMaps. If no such query is defined, this method will throw a CayenneRuntimeException.
      expireCachedLists - A flag that determines whether refresh of cached lists is required in case a query uses caching.
      Since:
      1.1
    • performQuery

      public List<?> performQuery​(String queryName, Map parameters, boolean expireCachedLists)
      Returns a list of objects or DataRows for a named query stored in one of the DataMaps. Internally Cayenne uses a caching policy defined in the named query. If refresh flag is true, a refresh is forced no matter what the caching policy is.
      Parameters:
      queryName - a name of a GenericSelectQuery defined in one of the DataMaps. If no such query is defined, this method will throw a CayenneRuntimeException.
      parameters - A map of parameters to use with stored query.
      expireCachedLists - A flag that determines whether refresh of cached lists is required in case a query uses caching.
      Since:
      1.1
    • isUsingSharedSnapshotCache

      public boolean isUsingSharedSnapshotCache()
      Returns true if the ObjectStore uses shared cache of a parent DataDomain.
      Since:
      1.1
    • setUsingSharedSnapshotCache

      public void setUsingSharedSnapshotCache​(boolean flag)
      Since:
      3.1
    • getGraphManager

      public GraphManager getGraphManager()
      Returns this context's ObjectStore.
      Specified by:
      getGraphManager in interface ObjectContext
      Specified by:
      getGraphManager in class BaseContext
      Since:
      1.2
    • fireDataChannelChanged

      protected void fireDataChannelChanged​(Object postedBy, GraphDiff changes)
      Overrides:
      fireDataChannelChanged in class BaseContext
    • setTransactionFactory

      @Deprecated public void setTransactionFactory​(TransactionFactory transactionFactory)
      Deprecated.
      since 4.0 avoid using this directly. Transaction management at this level will be eventually removed
      Since:
      4.0