Function PLy_exec_trigger

src/pl/plpython/plpy_exec.c:320–434

trigger subhandler * * the python function is expected to return Py_None if the tuple is * acceptable and unmodified. Otherwise it should return a PyString * object who's value is SKIP, or MODIFY. SKIP means don't perform * this action. MODIFY means the tuple has been modified, so update * tuple and perform action. SKIP and MODIFY assume the trigger fires * BEFORE the event and is ROW l

 * to take no arguments and return an argument of type trigger.
 */
HeapTuple
PLy_exec_trigger(FunctionCallInfo fcinfo, PLyProcedure *proc)
{
	HeapTuple	rv = NULL;
	PyObject   *volatile plargs = NULL;
	PyObject   *volatile plrv = NULL;
	TriggerData *tdata;
	TupleDesc	rel_descr;

	Assert(CALLED_AS_TRIGGER(fcinfo));
	tdata = (TriggerData *) fcinfo->context;

	/*
	 * Input/output conversion for trigger tuples.  We use the result and
	 * result_in fields to store the tuple conversion info.  We do this over
	 * again on each call to cover the possibility that the relation's tupdesc
	 * changed since the trigger was last called.  The PLy_xxx_setup_func
	 * calls should only happen once, but PLy_input_setup_tuple and
	 * PLy_output_setup_tuple are responsible for not doing repetitive work.
	 */
	rel_descr = RelationGetDescr(tdata->tg_relation);
	if (proc->result.typoid != rel_descr->tdtypeid)
		PLy_output_setup_func(&proc->result, proc->mcxt,
							  rel_descr->tdtypeid,
							  rel_descr->tdtypmod,
							  proc);
	if (proc->result_in.typoid != rel_descr->tdtypeid)
		PLy_input_setup_func(&proc->result_in, proc->mcxt,
							 rel_descr->tdtypeid,
							 rel_descr->tdtypmod,
							 proc);
	PLy_output_setup_tuple(&proc->result, rel_descr, proc);
	PLy_input_setup_tuple(&proc->result_in, rel_descr, proc);

	/*
	 * If the trigger is called recursively, we must push outer-level
	 * arguments into the stack.  This must be immediately before the PG_TRY
	 * to ensure that the corresponding pop happens.
	 */
	PLy_global_args_push(proc);

	PG_TRY();
	{
		int			rc PG_USED_FOR_ASSERTS_ONLY;

		rc = SPI_register_trigger_data(tdata);
		Assert(rc >= 0);

		plargs = PLy_trigger_build_args(fcinfo, proc, &rv);
		plrv = PLy_procedure_call(proc, "TD", plargs);

		Assert(plrv != NULL);

		/*
		 * Disconnect from SPI manager
		 */
		if (SPI_finish() != SPI_OK_FINISH)
			elog(ERROR, "SPI_finish failed");