Saving an object (inserts and updates)

To write an object into the database, call its save() method. Depending on whether the data object was newly created or was read from the database, the corresponding row in the database table is inserted or updated. If the object is new, its primary key(s) is/are generated automatically if the id method was set to "idbroker" or "native" in the schema.xml.

As an example, consider the following code, which creates an Author object and inserts it into the database. Then the object is loaded again, modified. and updates the corresponding row in the databse.

Author stevens = new Author();

If the generator properties "torque.complexObjectModel" and "torque.objectIsCaching" were not set to false at generation time, any objects which are referenced in the foreign key Lists of the object are also saved.

For example, in the following code, calling also saves the author added to the book:

Author bloch = new Author();
Book effective = new Book();
effective.setTitle("Effective Java");
bloch.addBook(effective);; //also saves the book "effective"

Note that the save is only propagated in the 1->n directions of foreign keys, not in the n->1 direction. I.e. in the above example, calling would NOT save the corresponding author.

If the object which save method is called is neither new nor modified, it is not saved. Internally, this is handled via the isNew and modifed flags of the object.

There are alternative ways to insert or update an object in the database: you can pass the objects to the doInsert() or doUpdate methods of their corresponding Peers, or you can create a criteria object which contains the data of the object and pass the Criteria object to the doInsert() or doUpdate methods of the Peer class. Note that if you construct a criteria, the id field is not added to the Criteria. It is taken care of by underlying database system (or perhaps the ID BROKER when it is in use). The object that is returned by doInsert is the id of the newly added row.

Deleting objects

Deletes work much in the same way as a select. If you, for example, want to delete the author with id = 3 then you simply add it to the Criteria and call doDelete.

Criteria criteria = new Criteria();
crit.add(AuthorPeer.AUTHOR_ID, 3);