public abstract class QueryJObjectContainer extends ReloadableJObjectContainer
Container backed by Permazen Java model objects acquired by performing
a transactional query and copying out the results into a SnapshotJTransaction.
The subclass method queryForObjects() performs the query returning the backing objects
within an already-opened transaction. The Items in the container are backed by in-memory copies
of the returned JObjects; these live inside a SnapshotJTransaction and therefore may persist indefinitely
after the query transaction closes.
Instances may be (re)loaded at any time by invoking reload(). During reload, the container opens a new
JTransaction, queries for objects using queryForObjects(), and copies each returned
object into the associated SnapshotJTransaction via copyWithRelated(),
which copies the object and any related objects necessary for resolving container properties. The set of related
objects associated with an object is determined by getRelatedObjects(); by default,
this is all directly referenced objects. Subclasses may override to customize.
It is up to queryForObjects() to determine what and how many objects are returned, their
sort order, etc. Any objects returned by queryForObjects() that are not instances of the
container's configured type are ignored.
@ProvidesProperty Limitations
The use of @ProvidesProperty methods has certain implications.
First, if the method reads any of the object's field(s) via their Java getter methods (as would normally be expected),
this will trigger a schema upgrade of the object if needed; however, this schema upgrade will occur in the
container's in-memory SnapshotJTransaction rather than in a real database transaction, so the
JObjectContainer.VERSION_PROPERTY will return a different schema version from what's in the database. The automatic schema
upgrade can be avoided if desired by reading the field using the appropriate JTransaction field access method
(e.g., JTransaction.readSimpleField()) and being prepared to handle a
UnknownFieldException if/when the object has an older schema version that does not contain
the requested field.
Secondly, because the values of reference fields (including complex sub-fields) are displayed using reference labels,
and these are typically derived from the referenced object's fields, those indirectly referenced objects need to be
copied into the container's SnapshotJTransaction as well. The easiest way to ensure these indirectly
referenced objects are copied is by overriding getRelatedObjects() as described above.
JObjectContainer.ObjFieldPropertyDef, JObjectContainer.ObjIdPropertyDef, JObjectContainer.ObjPropertyDef<T>, JObjectContainer.ObjTypePropertyDef, JObjectContainer.ObjVersionPropertyDef, JObjectContainer.RefLabelPropertyDefAbstractInMemoryContainer.BaseItemAddEvent, AbstractInMemoryContainer.BaseItemRemoveEventAbstractContainer.BaseItemSetChangeEvent, AbstractContainer.BasePropertySetChangeEventContainer.Editor, Container.Filter, Container.Filterable, Container.Hierarchical, Container.Indexed, Container.ItemSetChangeEvent, Container.ItemSetChangeListener, Container.ItemSetChangeNotifier, Container.Ordered, Container.PropertySetChangeEvent, Container.PropertySetChangeListener, Container.PropertySetChangeNotifier, Container.SimpleFilterable, Container.Sortable, Container.ViewerContainer.Indexed.ItemAddEvent, Container.Indexed.ItemRemoveEventjdb, log, OBJECT_ID_PROPERTY, REFERENCE_LABEL_PROPERTY, TYPE_PROPERTY, VERSION_PROPERTY| Modifier | Constructor and Description |
|---|---|
protected |
QueryJObjectContainer(Permazen jdb,
Class<?> type)
Constructor.
|
| Modifier and Type | Method and Description |
|---|---|
JObject |
copyWithRelated(JObject target,
JTransaction dest,
CopyState copyState)
Copy the given database object, and any related objects needed by any
@ProvidesProperty-annotated methods,
into the specified transaction. |
protected Iterable<? extends JObject> |
getRelatedObjects(JObject jobj)
Find objects related to the specified object that are needed by any
@ProvidesProperty-annotated
methods. |
protected abstract Iterator<? extends JObject> |
queryForObjects()
Query for the database objects that will be used to fill this container.
|
void |
reload()
(Re)load this container.
|
connect, disconnect, reloadAfterCommitcanSort, doInTransaction, getKeyFor, getOrderedPropertyNames, getPropertyValue, getType, load, load, setType, sort, updateItemgenerateItemId, getItemIdFor, getItemIdForSame, getJavaObject, resetItemIdsaddContainerFilter, addContainerFilter, afterReload, createBackedItem, getContainerFilters, getContainerProperty, getContainerPropertyIds, getItemIds, getPropertyExtractor, getSortableContainerPropertyIds, getType, getUnfilteredItem, internalRemoveAllItems, removeAllContainerFilters, removeContainerFilter, removeContainerFilters, setProperties, setProperty, setPropertyExtractor, sortaddContainerProperty, addFilter, addItem, addItem, addItemAfter, addItemAfter, addItemAt, addItemAt, addItemSetChangeListener, addListener, containsId, doFilterContainer, doSort, filterAll, fireItemAdded, fireItemRemoved, fireItemsAdded, fireItemsRemoved, firstItemId, getAllItemIds, getFilteredItemIds, getFilters, getFirstVisibleItem, getIdByIndex, getItem, getItemIds, getItemSorter, getSortablePropertyIds, getVisibleItemIds, hasContainerFilters, indexOfId, internalAddItemAfter, internalAddItemAt, internalAddItemAtEnd, internalRemoveItem, isFiltered, isFirstId, isLastId, isPropertyFiltered, lastItemId, nextItemId, passesFilters, prevItemId, registerNewItem, removeAllFilters, removeAllItems, removeContainerProperty, removeFilter, removeFilters, removeItem, removeItemSetChangeListener, removeListener, setAllItemIds, setFilteredItemIds, setFilters, setItemSorter, size, sortContaineraddListener, addPropertySetChangeListener, fireContainerPropertySetChange, fireContainerPropertySetChange, fireItemSetChange, fireItemSetChange, getItemSetChangeListeners, getListeners, getPropertySetChangeListeners, removeListener, removePropertySetChangeListener, setItemSetChangeListeners, setPropertySetChangeListenersclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitaddItemAfter, addItemAfter, firstItemId, isFirstId, isLastId, lastItemId, nextItemId, prevItemIdaddContainerProperty, addItem, addItem, containsId, getItem, removeAllItems, removeContainerProperty, removeItem, sizeprotected QueryJObjectContainer(Permazen jdb, Class<?> type)
jdb - Permazen databasetype - type restriction, or null for no restrictionIllegalArgumentException - if jdb is nullpublic void reload()
This creates a new JTransaction, invokes queryForObjects() to query for backing objects,
copies them into an in-memory SnapshotJTransaction via copyWithRelated(),
and builds the container from the result.
reload in class ReloadableJObjectContainerpublic JObject copyWithRelated(JObject target, JTransaction dest, CopyState copyState)
@ProvidesProperty-annotated methods,
into the specified transaction.
The implementation in JObjectContainer copies jobj, and all of jobj's related objects returned
by getRelatedObjects(), via JTransaction.copyTo(JTransaction, CopyState, Iterable).
target - the object to copy, or null (ignored)dest - destination transactioncopyState - tracks what's already been copiedtarget in dest, or null if target is nullgetRelatedObjects()protected Iterable<? extends JObject> getRelatedObjects(JObject jobj)
@ProvidesProperty-annotated
methods.
This defines all of the other objects on which any container property of jobj may depend.
These related objects will copied along with obj into the container's
SnapshotJTransaction when the container is (re)loaded.
The implementation in JObjectContainer returns all objects that are directly referenced by jobj,
delegating to Permazen.getReferencedObjects().
Subclasses may override this method to refine the selection.
jobj - the object being copiedIterable of additional objects to be copied, or null for none; any null values are ignoredIllegalArgumentException - if jobj is nullprotected abstract Iterator<? extends JObject> queryForObjects()
A JTransaction will be open in the current thread when this method is invoked.
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