Class DataContext

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

public class DataContext extends Object implements ObjectContext
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:
  • Field Details

    • threadObjectContext

      protected static final ThreadLocal<ObjectContext> threadObjectContext
      A holder of a ObjectContext bound to the current thread.
      Since:
      3.0
    • usingSharedSnapshotCache

      protected boolean usingSharedSnapshotCache
    • objectStore

      protected ObjectStore objectStore
    • graphAction

      protected ObjectContextGraphAction graphAction
      Graph action that handles property changes
      Since:
      3.1
    • userProperties

      protected volatile Map<String,Object> userProperties
      Stores user defined properties associated with this DataContext.
      Since:
      3.0
    • channel

      protected transient DataChannel channel
    • queryCache

      protected transient QueryCache queryCache
    • entityResolver

      protected transient EntityResolver entityResolver
    • 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
    • validatingObjectsOnCommit

      protected boolean validatingObjectsOnCommit
    • objectCreator

      protected transient org.apache.cayenne.access.DataContextObjectCreator objectCreator
  • 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

    • getThreadObjectContext

      public static ObjectContext getThreadObjectContext() throws IllegalStateException
      Returns the ObjectContext bound to the current thread.
      Returns:
      the ObjectContext associated with caller thread.
      Throws:
      IllegalStateException - if there is no ObjectContext bound to the current thread.
      Since:
      3.0
    • bindThreadObjectContext

      public static void bindThreadObjectContext(ObjectContext context)
      Binds a ObjectContext to the current thread. ObjectContext can later be retrieved by users in the same thread by calling getThreadObjectContext(). Using null parameter will unbind currently bound ObjectContext.
      Since:
      3.0
    • attachToRuntimeIfNeeded

      protected boolean attachToRuntimeIfNeeded()
      Checks whether this context is attached to Cayenne runtime stack and if not, attempts to attach itself to the runtime using Injector returned from the call to CayenneRuntime.getThreadInjector(). If thread Injector is not available and the context is not attached, throws CayenneRuntimeException.

      This method is called internally by the context before access to transient variables to allow the context to attach to the stack lazily following deserialization.

      Returns:
      true if the context successfully attached to the thread runtime, false - if it was already attached.
      Since:
      3.1
    • attachToRuntime

      protected void attachToRuntime(Injector injector)
      Attaches this context to the CayenneRuntime whose Injector is passed as an argument to this method.
      Since:
      3.1
    • attachToChannel

      protected void attachToChannel(DataChannel channel)
      Attaches to a provided DataChannel.
      Since:
      3.1
    • getChannel

      public DataChannel getChannel()
      Description copied from interface: ObjectContext
      Returns an DataChannel used by this context.
      Specified by:
      getChannel in interface ObjectContext
    • setChannel

      public void setChannel(DataChannel channel)
      Sets a new DataChannel for this context.
      Since:
      3.1
    • getEntityResolver

      public EntityResolver getEntityResolver()
      Description copied from interface: ObjectContext
      Returns EntityResolver that stores all mapping information accessible by this ObjectContext.
      Specified by:
      getEntityResolver in interface DataChannel
      Specified by:
      getEntityResolver in interface ObjectContext
    • setEntityResolver

      public void setEntityResolver(EntityResolver entityResolver)
      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.
      Specified by:
      hasChanges in interface ObjectContext
    • 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
    • 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
    • deleteObject

      public void deleteObject(Object object) throws DeleteDenyException
      Description copied from interface: ObjectContext
      Schedules deletion of a persistent object.
      Specified by:
      deleteObject in interface ObjectContext
      Throws:
      DeleteDenyException - if a DeleteRule.DENY delete rule is applicable for object deletion.
    • deleteObjects

      public <T> void deleteObjects(T... objects) throws DeleteDenyException
      Description copied from interface: ObjectContext
      Schedules deletion of one or more persistent objects. Same as ObjectContext.deleteObjects(Collection) only with a vararg argument list for easier deletion of individual objects.
      Specified by:
      deleteObjects in interface ObjectContext
      Throws:
      DeleteDenyException - if a DeleteRule.DENY delete rule is applicable for object deletion.
      Since:
      3.1
    • deleteObjects

      public void deleteObjects(Collection<?> objects) throws DeleteDenyException
      Description copied from interface: ObjectContext
      Schedules deletion of a collection of persistent objects.
      Specified by:
      deleteObjects in interface ObjectContext
      Throws:
      DeleteDenyException - if a DeleteRule.DENY delete rule is applicable for object deletion.
    • 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
    • uncommittedObjects

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

      public QueryCache getQueryCache()
    • setQueryCache

      public void setQueryCache(QueryCache queryCache)
      Sets a QueryCache to be used for storing cached query results.
    • getEventManager

      public EventManager getEventManager()
      Returns EventManager associated with the ObjectStore.
      Specified by:
      getEventManager in interface DataChannel
      Since:
      1.2
    • fireDataChannelCommitted

      protected void fireDataChannelCommitted(Object postedBy, GraphDiff changes)
      Since:
      1.2
    • fireDataChannelRolledback

      protected void fireDataChannelRolledback(Object postedBy, GraphDiff changes)
      Since:
      1.2
    • localObject

      public <T extends Persistent> T localObject(T objectFromAnotherContext)
      Description copied from interface: ObjectContext
      Returns a local copy of 'objectFromAnotherContext' object. "Local" means that the returned object is registered in this context. If the local object hasn't been previously cached in this context, a hollow object is created and returned to the caller. No DB query is performed to resolve an object.

      Note that passing an object with a non-existing id, may later result in FaultFailureException on attempt to read returned object properties.

      Specified by:
      localObject in interface ObjectContext
      Since:
      3.1
    • 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.

      Parameters:
      object - persistent object to create snapshot for
      Returns:
      current snapshot of the persistent object
      Since:
      1.1
    • prepareForAccess

      public void prepareForAccess(Persistent object, String property, boolean lazyFaulting)
      Description copied from interface: ObjectContext
      A callback method that child Persistent objects are expected to call before accessing property values. This callback allows ObjectContext to "inflate" unresolved objects on demand and also resolve properties that rely on lazy faulting.
      Specified by:
      prepareForAccess in interface ObjectContext
    • objectsFromDataRows

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

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

      public Persistent objectFromDataRow(String entityName, DataRow dataRow)
      Creates a Persistent from DataRow. This variety of the 'objectFromDataRow' method is normally used for generic classes.
      Since:
      3.1, 5.0 returns Persistent instead of the deprecated DataObject
      See Also:
    • newObject

      public <T> T newObject(Class<T> persistentClass)
      Creates and registers a new persistent object.
      Specified by:
      newObject in interface ObjectContext
      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 Persistent.

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

      public void unregisterObjects(Collection<?> objects)
      Unregisters a Collection of Persistent objects from the DataContext and the underlying ObjectStore. This operation also unsets DataContext for each object and changes its state to PersistenceState.TRANSIENT
      See Also:
    • invalidateObjects

      public void invalidateObjects(Collection<?> objects)
      Description copied from interface: ObjectContext
      Invalidates a Collection of persistent objects. This operation only applies to the objects already committed to the database and does nothing to the NEW objects. It would remove each object's snapshot from caches and change object's state to HOLLOW. On the next access to this object, the object will be refetched.
      Specified by:
      invalidateObjects in interface ObjectContext
    • invalidateObjects

      public <T> void invalidateObjects(T... objects)
      Description copied from interface: ObjectContext
      Invalidates one or more persistent objects. Same as ObjectContext.invalidateObjects(Collection) only with a vararg argument list for easier invalidation of individual objects. If no arguments are passed to this method, it does nothing.
      Specified by:
      invalidateObjects in interface ObjectContext
      Since:
      3.1
    • propertyChanged

      public void propertyChanged(Persistent object, String property, Object oldValue, Object newValue)
      Description copied from interface: ObjectContext
      A callback method that child Persistent objects are expected to call from inside the setter after modifying a value of a persistent property, including "simple" and "arc" properties.
      Specified by:
      propertyChanged in interface ObjectContext
    • 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
      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
    • 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
      Since:
      1.2
      See Also:
    • 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
      Throws:
      CayenneRuntimeException
    • onContextFlush

      protected GraphDiff onContextFlush(ObjectContext originatingContext, GraphDiff changes, boolean cascade)
    • select

      public <T> List<T> select(Select<T> query)
      Description copied from interface: ObjectContext
      Executes a selecting query, returning a list of persistent objects or data rows.
      Specified by:
      select in interface ObjectContext
      Since:
      4.0
    • selectOne

      public <T> T selectOne(Select<T> query)
      Description copied from interface: ObjectContext
      Executes a selecting query, returning either NULL if query matched no objects, or a single object. If query matches more than one object, CayenneRuntimeException is thrown.
      Specified by:
      selectOne in interface ObjectContext
      Since:
      4.0
    • selectFirst

      public <T> T selectFirst(Select<T> query)
      Description copied from interface: ObjectContext
      Selects a single object using provided query. The query itself can match any number of objects, but will return only the first one. It returns null if no objects were matched.

      If it matched more than one object, the first object from the list is returned. This makes 'selectFirst' different from ObjectContext.selectOne(Select), which would throw in this situation. 'selectFirst' is useful e.g. when the query is ordered and we only want to see the first object (e.g. "most recent news article"), etc.

      Selecting the first object via "Select.selectFirst(ObjectContext)" is more comprehensible than selecting via "ObjectContext.selectFirst(Select)", because implementations of "Select" set fetch size limit to one.

      Specified by:
      selectFirst in interface ObjectContext
      Since:
      4.0
    • iterate

      public <T> void iterate(Select<T> query, ResultIteratorCallback<T> callback)
      Description copied from interface: ObjectContext
      Creates a ResultIterator based on the provided query and passes it to a callback for processing. The caller does not need to worry about closing the iterator. This method takes care of it.
      Specified by:
      iterate in interface ObjectContext
      Since:
      4.0
    • iterator

      public <T> ResultIterator<T> iterator(Select<T> 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.

      Specified by:
      iterator in interface ObjectContext
    • 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 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
      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 Persistent objects or DataRows.

      Since 1.2 takes any Query parameter, not just GenericSelectQuery

      Specified by:
      performQuery in interface ObjectContext
      Returns:
      A list of Persistent objects or a DataRows, depending on the value returned by QueryMetadata.isFetchingDataRows(). Сan also return an iterator if the query is an instance of iteratedQuery.
    • 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.
      Specified by:
      onQuery in interface DataChannel
      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
    • onSync

      public GraphDiff onSync(ObjectContext originatingContext, GraphDiff changes, int syncType)
      Description copied from interface: DataChannel
      Processes synchronization request from a child ObjectContext, returning a GraphDiff that describes changes to objects made on the receiving end as a result of synchronization.
      Specified by:
      onSync in interface DataChannel
      Parameters:
      originatingContext - an ObjectContext that initiated the sync. Can be null.
      changes - diff from the context that initiated the sync.
      syncType - One of DataChannel.FLUSH_NOCASCADE_SYNC, DataChannel.FLUSH_CASCADE_SYNC, DataChannel.ROLLBACK_CASCADE_SYNC.
    • 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<String,?> 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
      Since:
      1.2
    • fireDataChannelChanged

      protected void fireDataChannelChanged(Object postedBy, GraphDiff changes)
      Since:
      1.2
    • 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
    • batchIterator

      public <T> ResultBatchIterator<T> batchIterator(Select<T> query, int size)
      Description copied from interface: ObjectContext
      Creates a ResultBatchIterator based on the provided query and batch size. 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 ResultBatchIterator explicitly.
      Specified by:
      batchIterator in interface ObjectContext
    • isValidatingObjectsOnCommit

      public boolean isValidatingObjectsOnCommit()
      Returns whether this ObjectContext performs object validation before commit is executed.
      Since:
      1.1
    • setValidatingObjectsOnCommit

      public void setValidatingObjectsOnCommit(boolean flag)
      Sets the property defining whether this ObjectContext should perform object validation before commit is executed.
      Since:
      1.1
    • getUserProperties

      protected Map<String,Object> getUserProperties()
      Returns a map of user-defined properties associated with this DataContext.
      Since:
      3.0
    • getUserProperty

      public Object getUserProperty(String key)
      Returns a user-defined property previously set via 'setUserProperty'. Note that it is a caller responsibility to synchronize access to properties.
      Specified by:
      getUserProperty in interface ObjectContext
      Since:
      3.0
    • setUserProperty

      public void setUserProperty(String key, Object value)
      Sets a user-defined property. Note that it is a caller responsibility to synchronize access to properties.
      Specified by:
      setUserProperty in interface ObjectContext
      Since:
      3.0
    • removeUserProperty

      public void removeUserProperty(String key)
      Removes a user-defined property.
      Specified by:
      removeUserProperty in interface ObjectContext
      Since:
      5.0
    • clearUserProperties

      public void clearUserProperties()
      Removes all user-defined properties.
      Specified by:
      clearUserProperties in interface ObjectContext
      Since:
      5.0