Examples of org.eclipse.persistence.sessions.UnitOfWork

org.eclipse.persistence.sessions.UnitOfWork

Purpose: To allow object level transactions. This class represents the public API of the unit of work and should be used to maintain complete compatibility.

Description: The unit of work is a session that implements all of the normal protocol of an EclipseLink session. It can be spawned from any other session including another unit of work. Objects can be brought into the unit of work through reading them or through registering them. The unit of work will operate on its own object space, that is the objects within the unit of work will be clones of the original objects. When the unit of work is committed, all changes to any objects registered within the unit of work will be committed to the database. A minimal commit/update will be performed and any foreign keys/circular reference/referential integrity will be resolved. If the commit to the database is successful the changed objects will be merged back into the unit of work parent session.

Responsibilities:

Allow parallel transactions against a session's objects.
Allow nested transactions.
Not require the application to write objects that is changes, automatically determine what has changed.
Perform a minimal commit/update of all changes that occurred.
Resolve foreign keys for newly created objects and maintain referential integrity.
Allow for the object transaction to use its own object space.

        // a named query created via ORM metadata processing needs initialization
        if (query instanceof JPAQuery) {
            query = ((JPAQuery) query).processSQLQuery(xrService.getORSession().getActiveSession());
        }


        UnitOfWork uow = xrService.getORSession().acquireUnitOfWork();
        Object toBeDeleted;


        // a query created via ORM metadata processing does not have parameters set, however, the operation should
        if (query.getArguments().size() == 0) {
            int idx = 0;
            for (Parameter  param : getParameters()) {
                // for custom SQL query (as configured via ORM metadata processing) we add args by position
                query.addArgument(Integer.toString(++idx), Util.SCHEMA_2_CLASS.get(param.getType()));
                query.addArgumentValue(invocation.getParameter(param.getName()));
            }
            toBeDeleted = uow.executeQuery(query);
        } else {
            // set query args or execute args for the non-JPAQuery case,
            // i.e. stored proc/funcs get populated from ORM metadata
            // whereas named queries (SQL strings) do not...
            List queryArguments = query.getArguments();
            int queryArgumentsSize = queryArguments.size();
            Vector executeArguments = new NonSynchronizedVector();
            for (int i = 0; i < queryArgumentsSize; i++) {
                String argName = (String)queryArguments.get(i);
                executeArguments.add(invocation.getParameter(argName));
            }
            toBeDeleted = uow.executeQuery(query, executeArguments);
        }


        // JPAQuery will return a single result in a Vector
        if (!isCollection() && toBeDeleted instanceof Vector) {
            if (((Vector) toBeDeleted).isEmpty()) {
                toBeDeleted = null;
            } else {
                toBeDeleted = ((Vector)toBeDeleted).firstElement();
            }
        }
        if (toBeDeleted != null) {
            uow.deleteObject(toBeDeleted);
            uow.commit();
        }
        return null;
    }

Examples of org.eclipse.persistence.sessions.UnitOfWork

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