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OAPI-895 dependent callbacks and integrity enforcement proposal #1578

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OAPI-895 dependent callbacks and integrity enforcement proposal #1578

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18 changes: 18 additions & 0 deletions docs/ActiveNode.rst
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Expand Up @@ -497,6 +497,10 @@ The available options are:

The two orphan-destruction options are unique to Neo4j.rb. As an example of when you'd use them, imagine you are modeling tours, routes, and stops along those routes. A tour can have multiple routes, a route can have multiple stops, a stop can be in multiple routes but must have at least one. When a route is destroyed, ``:delete_orphans`` would delete only those related stops that have no other routes.

The above callbacks are executed on association deletion and on node deletion for all associations of that node. The `delete` callbacks
are executed only once and do not propage further down the graph. The `destroy` callbacks are executed recursively until no more callbacks are found.


.. seealso::

.. raw:: html
Expand All @@ -512,6 +516,20 @@ The two orphan-destruction options are unique to Neo4j.rb. As an example of when
and
#has_one http://www.rubydoc.info/gems/neo4j/Neo4j/ActiveNode/HasN/ClassMethods#has_one-instance_method

Preserving has_one Integrity
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On creation of any relationship (with `ActiveRel.create` or with the generated association methods) that would create more than
one relationship where `:has_one` has been defined the previous relationship is removed. Optionally there is configuration option (which one?)
that causes an exception instead of automatic removal in case of the has_one constraint violation. Silently ignoring the violations is no longer supported.

In details that means before an operation adding or assigning 1 or more associations `ass`
on node `a` with a label `A` to node `b` with a label `B`
1. if `ass` is has_one any `ass` on any node with a label `A` and target node `b` and not part of the main operation
is destroyed (subject to dependent callbacks)
2. if the reverse reverse association `rev_ass` is has_one, any `rev_ass` between node `b` and any node with a Label `A`
and not part of the main operation is destroyed (subject to dependent callbacks).

Association Options
~~~~~~~~~~~~~~~~~~~~~~

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