Package org.apache.cayenne.access
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
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Field Summary
Fields Modifier and Type Field Description protected org.apache.cayenne.access.DataContextMergeHandlermergeHandlerprotected ObjectStoreobjectStoreprotected TransactionFactorytransactionFactoryDeprecated.since 4.0 used in a method that itself should be deprecated, so this is a temp codeprotected booleanusingSharedSnaphsotCacheFields inherited from class org.apache.cayenne.BaseContext
channel, entityResolver, graphAction, queryCache, threadObjectContext, userProperties, validatingObjectsOnCommitFields inherited from interface org.apache.cayenne.DataChannel
FLUSH_CASCADE_SYNC, FLUSH_NOCASCADE_SYNC, GRAPH_CHANGED_SUBJECT, GRAPH_FLUSHED_SUBJECT, GRAPH_ROLLEDBACK_SUBJECT, ROLLBACK_CASCADE_SYNC -
Constructor Summary
Constructors Constructor Description DataContext()Creates a new DataContext that is not attached to the Cayenne stack.DataContext(DataChannel channel, ObjectStore objectStore)Creates a new DataContext with parent DataChannel and ObjectStore. -
Method Summary
Modifier and Type Method Description protected voidattachToChannel(DataChannel channel)Attaches to a provided DataChannel.protected voidattachToRuntime(Injector injector)Attaches this context to the CayenneRuntime whose Injector is passed as an argument to this method.voidcommitChanges()Synchronizes object graph with the database.voidcommitChangesToParent()"Flushes" the changes to the parentDataChannel.DataRowcurrentSnapshot(Persistent object)Returns a DataRow reflecting current, possibly uncommitted, object state.Collection<?>deletedObjects()Returns a list of objects that are registered with this DataContext and have a state PersistenceState.DELETEDprotected voidfireDataChannelChanged(Object postedBy, GraphDiff changes)DataContextDelegategetDelegate()Returns a delegate currently associated with this DataContext.GraphManagergetGraphManager()Returns this context's ObjectStore.ObjectStoregetObjectStore()Returns ObjectStore associated with this DataContext.DataDomaingetParentDataDomain()Returns a DataDomain used by this DataContext.booleanhasChanges()Returnstrueif there are any modified, deleted or new objects registered with this DataContext,falseotherwise.booleanisUsingSharedSnapshotCache()Returnstrueif the ObjectStore uses shared cache of a parent DataDomain.<T> ResultIterator<T>iterator(Select<T> query)Creates a ResultIterator based on the provided query.Collection<?>modifiedObjects()Returns a list of objects that are registered with this DataContext and have a state PersistenceState.MODIFIED<T> TnewObject(Class<T> persistentClass)Creates and registers a new persistent object.PersistentnewObject(String entityName)Instantiates a new object and registers it with this context.Collection<?>newObjects()Returns a list of objects that are registered with this DataContext and have a state PersistenceState.NEW<T extends Persistent>
TobjectFromDataRow(Class<T> objectClass, DataRow dataRow)Creates a DataObject from DataRow.DataObjectobjectFromDataRow(String entityName, DataRow dataRow)Creates a DataObject from DataRow.ListobjectsFromDataRows(ClassDescriptor descriptor, List<? extends DataRow> dataRows)Converts a list of DataRows to a List of DataObject registered with this DataContext.protected GraphDiffonContextFlush(ObjectContext originatingContext, GraphDiff changes, boolean cascade)QueryResponseonQuery(ObjectContext context, Query query)An implementation of aDataChannelmethod that is used by child contexts to execute queries.QueryResponseperformGenericQuery(Query query)Executes a query returning a generic response.ResultIteratorperformIteratedQuery(Query query)Performs a single database select query returning result as a ResultIterator.int[]performNonSelectingQuery(String queryName)Performs a named mapped query that does not select rows.int[]performNonSelectingQuery(String queryName, Map<String,?> parameters)Performs a named mapped non-selecting query using a map of parameters.int[]performNonSelectingQuery(Query query)Performs a single database query that does not select rows.List<?>performQuery(String queryName, boolean expireCachedLists)Returns a list of objects or DataRows for a named query stored in one of the DataMaps.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.ListperformQuery(Query query)Performs a single selecting query.voidregisterNewObject(Object object)Registers a transient object with the context, recursively registering all transient persistent objects attached to this object via relationships.voidrollbackChanges()Reverts any changes that have occurred to objects registered with DataContext; also performs cascading rollback of all parent DataContexts.voidrollbackChangesLocally()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.voidsetDelegate(DataContextDelegate delegate)Sets a DataContextDelegate for this context.voidsetTransactionFactory(TransactionFactory transactionFactory)Deprecated.since 4.0 avoid using this directly.voidsetUsingSharedSnapshotCache(boolean flag)Collection<?>uncommittedObjects()Returns a collection of all uncommitted registered objects.voidunregisterObjects(Collection dataObjects)Unregisters a Collection of DataObjects from the DataContext and the underlying ObjectStore.Methods inherited from class org.apache.cayenne.BaseContext
attachToRuntimeIfNeeded, batchIterator, bindThreadObjectContext, deleteObject, deleteObjects, deleteObjects, fireDataChannelCommitted, fireDataChannelRolledback, getChannel, getEntityResolver, getEventManager, getQueryCache, getThreadObjectContext, getUserProperties, getUserProperty, injectInitialValue, invalidateObjects, invalidateObjects, isValidatingObjectsOnCommit, iterate, localObject, onSync, prepareForAccess, propertyChanged, select, selectFirst, selectOne, setChannel, setEntityResolver, setQueryCache, setUserProperty, setValidatingObjectsOnCommit
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Field Details
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objectStore
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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
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Constructor Details
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DataContext
public DataContext()Creates a new DataContext that is not attached to the Cayenne stack. -
DataContext
Creates a new DataContext with parent DataChannel and ObjectStore.- Since:
- 1.2
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Method Details
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attachToRuntime
Description copied from class:BaseContextAttaches this context to the CayenneRuntime whose Injector is passed as an argument to this method.- Overrides:
attachToRuntimein classBaseContext
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attachToChannel
Description copied from class:BaseContextAttaches to a provided DataChannel.- Overrides:
attachToChannelin classBaseContext- Since:
- 3.1
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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
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setDelegate
Sets a DataContextDelegate for this context. Delegate is notified of certain events in the DataContext lifecycle and can customize DataContext behavior.- Since:
- 1.1
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getDelegate
Returns a delegate currently associated with this DataContext.- Since:
- 1.1
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getObjectStore
Returns ObjectStore associated with this DataContext. -
hasChanges
public boolean hasChanges()Returnstrueif there are any modified, deleted or new objects registered with this DataContext,falseotherwise. -
newObjects
Returns a list of objects that are registered with this DataContext and have a state PersistenceState.NEW- Specified by:
newObjectsin interfaceObjectContext- Specified by:
newObjectsin classBaseContext
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deletedObjects
Returns a list of objects that are registered with this DataContext and have a state PersistenceState.DELETED- Specified by:
deletedObjectsin interfaceObjectContext- Specified by:
deletedObjectsin classBaseContext
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modifiedObjects
Returns a list of objects that are registered with this DataContext and have a state PersistenceState.MODIFIED- Specified by:
modifiedObjectsin interfaceObjectContext- Specified by:
modifiedObjectsin classBaseContext
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uncommittedObjects
Returns a collection of all uncommitted registered objects.- Specified by:
uncommittedObjectsin interfaceObjectContext- Specified by:
uncommittedObjectsin classBaseContext- Since:
- 1.2
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currentSnapshot
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
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objectsFromDataRows
Converts a list of DataRows to a List of DataObject registered with this DataContext.- Since:
- 3.0
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objectFromDataRow
Creates a DataObject from DataRow.- Since:
- 3.1
- See Also:
DataRow
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objectFromDataRow
Creates a DataObject from DataRow. This variety of the 'objectFromDataRow' method is normally used for generic classes.- Since:
- 3.1
- See Also:
DataRow
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newObject
Creates and registers a new persistent object.- Specified by:
newObjectin interfaceObjectContext- Specified by:
newObjectin classBaseContext- Since:
- 1.2
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newObject
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
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registerNewObject
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:
registerNewObjectin interfaceObjectContext- Specified by:
registerNewObjectin classBaseContext- Parameters:
object- new object that needs to be made persistent.
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unregisterObjects
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. -
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:
rollbackChangesLocallyin interfaceObjectContext- Specified by:
rollbackChangesLocallyin classBaseContext- Since:
- 1.2
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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:
rollbackChangesin interfaceObjectContext- Specified by:
rollbackChangesin classBaseContext
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commitChangesToParent
public void commitChangesToParent()"Flushes" the changes to the parentDataChannel. 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 usecommitChanges().- Specified by:
commitChangesToParentin interfaceObjectContext- Specified by:
commitChangesToParentin classBaseContext- Since:
- 1.2
- See Also:
commitChanges()
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commitChanges
Synchronizes object graph with the database. Executes needed insert, update and delete queries (generated internally).- Specified by:
commitChangesin interfaceObjectContext- Specified by:
commitChangesin classBaseContext- Throws:
CayenneRuntimeException
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onContextFlush
protected GraphDiff onContextFlush(ObjectContext originatingContext, GraphDiff changes, boolean cascade)- Specified by:
onContextFlushin classBaseContext
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iterator
Description copied from interface:ObjectContextCreates 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 useObjectContext.iterate(Select, ResultIteratorCallback)as an alternative.- Specified by:
iteratorin interfaceObjectContext- Specified by:
iteratorin classBaseContext
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performIteratedQuery
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
Executes a query returning a generic response.- Specified by:
performGenericQueryin interfaceObjectContext- Specified by:
performGenericQueryin classBaseContext- Since:
- 1.2
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performQuery
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:
performQueryin interfaceObjectContext- Specified by:
performQueryin classBaseContext- Returns:
- A list of DataObjects or a DataRows, depending on the value
returned by
QueryMetadata.isFetchingDataRows().
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onQuery
An implementation of aDataChannelmethod 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
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performNonSelectingQuery
Performs a single database query that does not select rows. Returns an array of update counts.- Since:
- 1.1
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performNonSelectingQuery
Performs a named mapped query that does not select rows. Returns an array of update counts.- Since:
- 1.1
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performNonSelectingQuery
Performs a named mapped non-selecting query using a map of parameters. Returns an array of update counts.- Since:
- 1.1
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performQuery
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
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performQuery
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
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getGraphManager
Returns this context's ObjectStore.- Specified by:
getGraphManagerin interfaceObjectContext- Specified by:
getGraphManagerin classBaseContext- Since:
- 1.2
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fireDataChannelChanged
- Overrides:
fireDataChannelChangedin classBaseContext
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setTransactionFactory
Deprecated.since 4.0 avoid using this directly. Transaction management at this level will be eventually removed- Since:
- 4.0
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