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1 """GnuMed database object business class.
2
3 Overview
4 --------
5 This class wraps a source relation (table, view) which
6 represents an entity that makes immediate business sense
7 such as a vaccination or a medical document. In many if
8 not most cases this source relation is a denormalizing
9 view. The data in that view will in most cases, however,
10 originate from several normalized tables. One instance
11 of this class represents one row of said source relation.
12
13 Note, however, that this class does not *always* simply
14 wrap a single table or view. It can also encompass several
15 relations (views, tables, sequences etc) that taken together
16 form an object meaningful to *business* logic.
17
18 Initialization
19 --------------
20 There are two ways to initialize an instance with values.
21 One way is to pass a "primary key equivalent" object into
22 __init__(). Refetch_payload() will then pull the data from
23 the backend. Another way would be to fetch the data outside
24 the instance and pass it in via the <row> argument. In that
25 case the instance will not initially connect to the databse
26 which may offer a great boost to performance.
27
28 Values API
29 ----------
30 Field values are cached for later access. They can be accessed
31 by a dictionary API, eg:
32
33 old_value = object['field']
34 object['field'] = new_value
35
36 The field names correspond to the respective column names
37 in the "main" source relation. Accessing non-existant field
38 names will raise an error, so does trying to set fields not
39 listed in self.__class__._updatable_fields. To actually
40 store updated values in the database one must explicitly
41 call save_payload().
42
43 The class will in many cases be enhanced by accessors to
44 related data that is not directly part of the business
45 object itself but are closely related, such as codes
46 linked to a clinical narrative entry (eg a diagnosis). Such
47 accessors in most cases start with get_*. Related setters
48 start with set_*. The values can be accessed via the
49 object['field'] syntax, too, but they will be cached
50 independantly.
51
52 Concurrency handling
53 --------------------
54 GnuMed connections always run transactions in isolation level
55 "serializable". This prevents transactions happening at the
56 *very same time* to overwrite each other's data. All but one
57 of them will abort with a concurrency error (eg if a
58 transaction runs a select-for-update later than another one
59 it will hang until the first transaction ends. Then it will
60 succeed or fail depending on what the first transaction
61 did). This is standard transactional behaviour.
62
63 However, another transaction may have updated our row
64 between the time we first fetched the data and the time we
65 start the update transaction. This is noticed by getting the
66 XMIN system column for the row when initially fetching the
67 data and using that value as a where condition value when
68 updating the row later. If the row had been updated (xmin
69 changed) or deleted (primary key disappeared) in the
70 meantime the update will touch zero rows (as no row with
71 both PK and XMIN matching is found) even if the query itself
72 syntactically succeeds.
73
74 When detecting a change in a row due to XMIN being different
75 one needs to be careful how to represent that to the user.
76 The row may simply have changed but it also might have been
77 deleted and a completely new and unrelated row which happens
78 to have the same primary key might have been created ! This
79 row might relate to a totally different context (eg. patient,
80 episode, encounter).
81
82 One can offer all the data to the user:
83
84 self.original_payload
85 - contains the data at the last successful refetch
86
87 self.modified_payload
88 - contains the modified payload just before the last
89 failure of save_payload() - IOW what is currently
90 in the database
91
92 self._payload
93 - contains the currently active payload which may or
94 may not contain changes
95
96 For discussion on this see the thread starting at:
97
98 http://archives.postgresql.org/pgsql-general/2004-10/msg01352.php
99
100 and here
101
102 http://groups.google.com/group/pgsql.general/browse_thread/thread/e3566ba76173d0bf/6cf3c243a86d9233
103 (google for "XMIN semantic at peril")
104
105 Problem cases with XMIN:
106
107 1) not unlikely
108 - a very old row is read with XMIN
109 - vacuum comes along and sets XMIN to FrozenTransactionId
110 - now XMIN changed but the row actually didn't !
111 - an update with "... where xmin = old_xmin ..." fails
112 although there is no need to fail
113
114 2) quite unlikely
115 - a row is read with XMIN
116 - a long time passes
117 - the original XMIN gets frozen to FrozenTransactionId
118 - another writer comes along and changes the row
119 - incidentally the exact same old row gets the old XMIN *again*
120 - now XMIN is (again) the same but the data changed !
121 - a later update fails to detect the concurrent change !!
122
123 TODO:
124 The solution is to use our own column for optimistic locking
125 which gets updated by an AFTER UPDATE trigger.
126 """
127 #============================================================
128 # $Source: /cvsroot/gnumed/gnumed/gnumed/client/pycommon/gmBusinessDBObject.py,v $
129 # $Id: gmBusinessDBObject.py,v 1.60 2009/12/21 15:02:17 ncq Exp $
130 __version__ = "$Revision: 1.60 $"
131 __author__ = "K.Hilbert <Karsten.Hilbert@gmx.net>"
132 __license__ = "GPL"
133
134 import sys, copy, types, inspect, logging
135
136
137 if __name__ == '__main__':
138 sys.path.insert(0, '../../')
139 from Gnumed.pycommon import gmExceptions, gmPG2
140
141
142 _log = logging.getLogger('gm.db')
143 _log.info(__version__)
144 #============================================================
146 """Represents business objects in the database.
147
148 Rules:
149 - instances ARE ASSUMED TO EXIST in the database
150 - PK construction (aPK_obj): DOES verify its existence on instantiation
151 (fetching data fails)
152 - Row construction (row): allowed by using a dict of pairs
153 field name: field value (PERFORMANCE improvement)
154 - does NOT verify FK target existence
155 - does NOT create new entries in the database
156 - does NOT lazy-fetch fields on access
157
158 Class scope SQL commands and variables:
159
160 <_cmd_fetch_payload>
161 - must return exactly one row
162 - where clause argument values are expected
163 in self.pk_obj (taken from __init__(aPK_obj))
164 - must return xmin of all rows that _cmds_store_payload
165 will be updating, so views must support the xmin columns
166 of their underlying tables
167
168 <_cmds_store_payload>
169 - one or multiple "update ... set ... where xmin_* = ..." statements
170 which actually update the database from the data in self._payload,
171 - the last query must refetch the XMIN values needed to detect
172 concurrent updates, their field names had better be the same as
173 in _cmd_fetch_payload
174
175 <_updatable_fields>
176 - a list of fields available for update via object['field']
177
178 """
179 #--------------------------------------------------------
181 """Init business object.
182 """
183 # initialize those "too early" because checking descendants might
184 # fail which will then call __str__ in stack trace logging if --debug
185 # was given which in turn needs those instance variables
186 self.pk_obj = '<uninitialized>'
187 self._idx = {}
188 self._payload = [] # the cache for backend object values (mainly table fields)
189 self._ext_cache = {} # the cache for extended method's results
190 self._is_modified = False
191
192 # check descendants
193 self.__class__._cmd_fetch_payload
194 self.__class__._cmds_store_payload
195 self.__class__._updatable_fields
196
197 if aPK_obj is not None:
198 self.__init_from_pk(aPK_obj=aPK_obj)
199 else:
200 self._init_from_row_data(row=row)
201
202 self._is_modified = False
203 #--------------------------------------------------------
205 """Creates a new clinical item instance by its PK.
206
207 aPK_obj can be:
208 - a simple value
209 * the primary key WHERE condition must be
210 a simple column
211 - a dictionary of values
212 * the primary key where condition must be a
213 subselect consuming the dict and producing
214 the single-value primary key
215 """
216 self.pk_obj = aPK_obj
217 result = self.refetch_payload()
218 if result is True:
219 self.original_payload = {}
220 for field in self._idx.keys():
221 self.original_payload[field] = self._payload[self._idx[field]]
222 return True
223
224 if result is False:
225 raise gmExceptions.ConstructorError, "[%s:%s]: error loading instance" % (self.__class__.__name__, self.pk_obj)
226 #--------------------------------------------------------
228 """Creates a new clinical item instance given its fields.
229
230 row must be a dict with the fields:
231 - pk_field: the name of the primary key field
232 - idx: a dict mapping field names to position
233 - data: the field values in a list (as returned by
234 cursor.fetchone() in the DB-API)
235 """
236 try:
237 self._idx = row['idx']
238 self._payload = row['data']
239 self.pk_obj = self._payload[self._idx[row['pk_field']]]
240 except:
241 _log.exception('faulty <row> argument structure: %s' % row)
242 raise gmExceptions.ConstructorError, "[%s:??]: error loading instance from row data" % self.__class__.__name__
243
244 if len(self._idx.keys()) != len(self._payload):
245 _log.critical('field index vs. payload length mismatch: %s field names vs. %s fields' % (len(self._idx.keys()), len(self._payload)))
246 _log.critical('faulty <row> argument structure: %s' % row)
247 raise gmExceptions.ConstructorError, "[%s:??]: error loading instance from row data" % self.__class__.__name__
248
249 self.original_payload = {}
250 for field in self._idx.keys():
251 self.original_payload[field] = self._payload[self._idx[field]]
252 #--------------------------------------------------------
254 if self.__dict__.has_key('_is_modified'):
255 if self._is_modified:
256 _log.critical('[%s:%s]: loosing payload changes' % (self.__class__.__name__, self.pk_obj))
257 _log.debug('original: %s' % self.original_payload)
258 _log.debug('modified: %s' % self._payload)
259 #--------------------------------------------------------
261 tmp = []
262 try:
263 for attr in self._idx.keys():
264 if self._payload[self._idx[attr]] is None:
265 tmp.append(u'%s: NULL' % attr)
266 else:
267 tmp.append('%s: >>%s<<' % (attr, self._payload[self._idx[attr]]))
268 return '[%s:%s]: %s' % (self.__class__.__name__, self.pk_obj, str(tmp))
269 except:
270 return 'nascent [%s @ %s], cannot show payload and primary key' %(self.__class__.__name__, id(self))
271 #--------------------------------------------------------
273 # use try: except: as it is faster and we want this as fast as possible
274
275 # 1) backend payload cache
276 try:
277 return self._payload[self._idx[attribute]]
278 except KeyError:
279 pass
280
281 # 2) extension method results ...
282 getter = getattr(self, 'get_%s' % attribute, None)
283 if not callable(getter):
284 _log.warning('[%s]: no attribute [%s]' % (self.__class__.__name__, attribute))
285 _log.warning('[%s]: valid attributes: %s' % (self.__class__.__name__, str(self._idx.keys())))
286 _log.warning('[%s]: no getter method [get_%s]' % (self.__class__.__name__, attribute))
287 methods = filter(lambda x: x[0].startswith('get_'), inspect.getmembers(self, inspect.ismethod))
288 _log.warning('[%s]: valid getter methods: %s' % (self.__class__.__name__, str(methods)))
289 raise gmExceptions.NoSuchBusinessObjectAttributeError, '[%s]: cannot access [%s]' % (self.__class__.__name__, attribute)
290
291 self._ext_cache[attribute] = getter()
292 return self._ext_cache[attribute]
293 #--------------------------------------------------------
295
296 # 1) backend payload cache
297 if attribute in self.__class__._updatable_fields:
298 try:
299 if self._payload[self._idx[attribute]] != value:
300 self._payload[self._idx[attribute]] = value
301 self._is_modified = True
302 return
303 except KeyError:
304 _log.warning('[%s]: cannot set attribute <%s> despite marked settable' % (self.__class__.__name__, attribute))
305 _log.warning('[%s]: supposedly settable attributes: %s' % (self.__class__.__name__, str(self.__class__._updatable_fields)))
306 raise gmExceptions.NoSuchBusinessObjectAttributeError, '[%s]: cannot access [%s]' % (self.__class__.__name__, attribute)
307
308 # 2) setters providing extensions
309 if hasattr(self, 'set_%s' % attribute):
310 setter = getattr(self, "set_%s" % attribute)
311 if not callable(setter):
312 raise gmExceptions.NoSuchBusinessObjectAttributeError, '[%s] setter [set_%s] not callable' % (self.__class__.__name__, attribute)
313 try:
314 del self._ext_cache[attribute]
315 except KeyError:
316 pass
317 if type(value) is types.TupleType:
318 if setter(*value):
319 self._is_modified = True
320 return
321 raise gmExceptions.BusinessObjectAttributeNotSettableError, '[%s]: setter [%s] failed for [%s]' % (self.__class__.__name__, setter, value)
322 if setter(value):
323 self._is_modified = True
324 return
325
326 # 3) don't know what to do with <attribute>
327 _log.error('[%s]: cannot find attribute <%s> or setter method [set_%s]' % (self.__class__.__name__, attribute, attribute))
328 _log.warning('[%s]: settable attributes: %s' % (self.__class__.__name__, str(self.__class__._updatable_fields)))
329 methods = filter(lambda x: x[0].startswith('set_'), inspect.getmembers(self, inspect.ismethod))
330 _log.warning('[%s]: valid setter methods: %s' % (self.__class__.__name__, str(methods)))
331 raise gmExceptions.BusinessObjectAttributeNotSettableError, '[%s]: cannot set [%s]' % (self.__class__.__name__, attribute)
332 #--------------------------------------------------------
333 # external API
334 #--------------------------------------------------------
336 raise NotImplementedError('comparison between [%s] and [%s] not implemented' % (self, another_object))
337 #--------------------------------------------------------
340 #--------------------------------------------------------
342 return self._idx.keys()
343 #--------------------------------------------------------
345 return self.__class__._updatable_fields
346 #--------------------------------------------------------
348 _log.error('[%s:%s]: forgot to override get_patient()' % (self.__class__.__name__, self.pk_obj))
349 return None
350 #--------------------------------------------------------
352 """Fetch field values from backend.
353 """
354 if self._is_modified:
355 if ignore_changes:
356 _log.critical('[%s:%s]: loosing payload changes' % (self.__class__.__name__, self.pk_obj))
357 _log.debug('original: %s' % self.original_payload)
358 _log.debug('modified: %s' % self._payload)
359 else:
360 _log.critical('[%s:%s]: cannot reload, payload changed' % (self.__class__.__name__, self.pk_obj))
361 return False
362
363 if type(self.pk_obj) == types.DictType:
364 arg = self.pk_obj
365 else:
366 arg = [self.pk_obj]
367 rows, self._idx = gmPG2.run_ro_queries (
368 queries = [{'cmd': self.__class__._cmd_fetch_payload, 'args': arg}],
369 get_col_idx = True
370 )
371 if len(rows) == 0:
372 _log.error('[%s:%s]: no such instance' % (self.__class__.__name__, self.pk_obj))
373 return False
374 self._payload = rows[0]
375 return True
376 #--------------------------------------------------------
379 #--------------------------------------------------------
381 return self.save_payload(conn = conn)
382 #--------------------------------------------------------
384 """Store updated values (if any) in database.
385
386 Optionally accepts a pre-existing connection
387 - returns a tuple (<True|False>, <data>)
388 - True: success
389 - False: an error occurred
390 * data is (error, message)
391 * for error meanings see gmPG2.run_rw_queries()
392 """
393 if not self._is_modified:
394 return (True, None)
395
396 args = {}
397 for field in self._idx.keys():
398 args[field] = self._payload[self._idx[field]]
399 self.modified_payload = args
400
401 close_conn = self.__noop
402 if conn is None:
403 conn = gmPG2.get_connection(readonly=False)
404 close_conn = conn.close
405
406 # query succeeded but failed to find the row to lock
407 # because another transaction committed an UPDATE or
408 # DELETE *before* we attempted to lock it ...
409 # FIXME: this can fail if savepoints are used since subtransactions change the xmin/xmax ...
410
411 queries = []
412 for query in self.__class__._cmds_store_payload:
413 queries.append({'cmd': query, 'args': args})
414 rows, idx = gmPG2.run_rw_queries (
415 link_obj = conn,
416 queries = queries,
417 return_data = True,
418 get_col_idx = True
419 )
420
421 # update cached XMIN values (should be in first-and-only result row of last query)
422 row = rows[0]
423 for key in idx:
424 try:
425 self._payload[self._idx[key]] = row[idx[key]]
426 except KeyError:
427 conn.rollback()
428 close_conn()
429 _log.error('[%s:%s]: cannot update instance, XMIN refetch key mismatch on [%s]' % (self.__class__.__name__, self.pk_obj, key))
430 _log.error('payload keys: %s' % str(self._idx))
431 _log.error('XMIN refetch keys: %s' % str(idx))
432 _log.error(args)
433 raise
434
435 conn.commit()
436 close_conn()
437
438 self._is_modified = False
439 # update to new "original" payload
440 self.original_payload = {}
441 for field in self._idx.keys():
442 self.original_payload[field] = self._payload[self._idx[field]]
443
444 return (True, None)
445 #============================================================
446 if __name__ == '__main__':
447 #--------------------------------------------------------
449 _cmd_fetch_payload = None
450 _cmds_store_payload = None
451 _updatable_fields = []
452 #----------------------------------------------------
455 #----------------------------------------------------
458 #--------------------------------------------------------
459 if len(sys.argv) > 1 and sys.argv[1] == u'test':
460
461 from Gnumed.pycommon import gmI18N
462 gmI18N.activate_locale()
463 gmI18N.install_domain()
464
465 data = {
466 'pk_field': 'bogus_pk',
467 'idx': {'bogus_pk': 0, 'bogus_field': 1},
468 'data': [-1, 'bogus_data']
469 }
470 obj = cTestObj(row=data)
471 #print obj['wrong_field']
472 obj['wrong_field'] = 1
473
474 #============================================================
475 # $Log: gmBusinessDBObject.py,v $
476 # Revision 1.60 2009/12/21 15:02:17 ncq
477 # - fix typo
478 #
479 # Revision 1.59 2009/11/30 15:06:50 ncq
480 # - slightly improved __str__
481 #
482 # Revision 1.58 2009/11/28 18:27:50 ncq
483 # - cleanup
484 #
485 # Revision 1.57 2009/09/13 18:27:38 ncq
486 # - cleanup
487 #
488 # Revision 1.56 2009/04/13 10:37:41 ncq
489 # - support same_payload
490 # - support save around save_payload
491 #
492 # Revision 1.55 2009/02/18 13:44:32 ncq
493 # - streamline exception handling in __init__
494 #
495 # Revision 1.54 2009/01/02 11:37:09 ncq
496 # - teach refetch_payload to ignore changes on demand
497 #
498 # Revision 1.53 2008/12/26 22:33:57 ncq
499 # - cleanup
500 #
501 # Revision 1.52 2008/12/25 16:53:18 ncq
502 # - business object base class really should support properties
503 # so make it inherit from object
504 #
505 # Revision 1.51 2008/11/20 18:43:01 ncq
506 # - better logger name
507 #
508 # Revision 1.50 2008/10/22 12:06:48 ncq
509 # - more careful __str__ for early failure
510 #
511 # Revision 1.49 2008/10/12 15:39:49 ncq
512 # - set up instance vars before testing for consts so if we fail they exist
513 #
514 # Revision 1.48 2007/12/12 16:17:15 ncq
515 # - better logger names
516 #
517 # Revision 1.47 2007/12/11 14:17:18 ncq
518 # - use stdlib logging
519 #
520 # Revision 1.46 2007/11/28 13:58:32 ncq
521 # - hide one less exception
522 #
523 # Revision 1.45 2007/10/19 12:49:39 ncq
524 # - much improved XMIN docs, TODO for XMIN removal
525 #
526 # Revision 1.44 2007/10/12 07:26:25 ncq
527 # - somewhat improved docs
528 #
529 # Revision 1.43 2007/08/13 21:55:10 ncq
530 # - fix logging statement
531 #
532 # Revision 1.42 2007/05/21 14:47:22 ncq
533 # - no caching of get_*()ers anymore, but don't deprecate them eiter
534 #
535 # Revision 1.41 2007/05/19 23:12:28 ncq
536 # - cleanup
537 # - remove _subtable support
538 #
539 # Revision 1.40 2006/11/14 23:30:33 ncq
540 # - fix var name
541 #
542 # Revision 1.39 2006/10/31 15:59:47 ncq
543 # - we are dealing with gmPG2 now
544 #
545 # Revision 1.38 2006/10/23 13:22:07 ncq
546 # - no conn pool no more
547 #
548 # Revision 1.37 2006/10/21 20:39:48 ncq
549 # - a bunch of cleanup
550 #
551 # Revision 1.36 2006/10/09 11:42:16 ncq
552 # - in refetch_payload() properly handle scalar vs complex self.pk_obj
553 #
554 # Revision 1.35 2006/10/08 14:26:16 ncq
555 # - convert to use gmPG2
556 # - subtable support may still be suffering fallout
557 # - better docstrings
558 # - drop _cmds_lock_rows_for_update
559 # - must use xmin=... in UPDATE now
560 # - drop self._service
561 # - adjust test suite
562 #
563 # Revision 1.34 2006/07/19 20:27:03 ncq
564 # - gmPyCompat.py is history
565 #
566 # Revision 1.33 2006/06/18 13:20:29 ncq
567 # - cleanup, better logging
568 #
569 # Revision 1.32 2006/06/17 16:41:30 ncq
570 # - only modify self._data if it actually changes
571 # - don't close the connection if it was passed in
572 #
573 # Revision 1.31 2005/11/19 08:47:56 ihaywood
574 # tiny bugfixes
575 #
576 # Revision 1.30 2005/10/19 09:12:00 ncq
577 # - cleanup
578 #
579 # Revision 1.29 2005/10/15 18:17:06 ncq
580 # - error detection in subtable support much improved
581 #
582 # Revision 1.28 2005/10/10 17:40:57 ncq
583 # - slightly enhance Syans fixes on AttributeError
584 #
585 # Revision 1.27 2005/10/08 12:33:08 sjtan
586 # tree can be updated now without refetching entire cache; done by passing emr object to create_xxxx methods and calling emr.update_cache(key,obj);refresh_historical_tree non-destructively checks for changes and removes removed nodes and adds them if cache mismatch.
587 #
588 # Revision 1.26 2005/10/04 11:39:58 sjtan
589 # catch missing attribute error.
590 #
591 # Revision 1.25 2005/06/15 22:26:20 ncq
592 # - CAVEAT regarding XMIN vs. savepoints
593 #
594 # Revision 1.24 2005/05/04 08:54:00 ncq
595 # - improved __setitem__ handling
596 # - add_to_subtable()/del_from_subtable() now set _is_modified appropriately
597 # - some internal renaming for clarification
598 #
599 # Revision 1.23 2005/04/29 15:28:47 ncq
600 # - one fix to del_from_subtable() as approved by Ian
601 # - some internal renaming to clear things up
602 #
603 # Revision 1.22 2005/04/28 21:10:20 ncq
604 # - improved _subtable docs
605 # - avoid confusion:
606 # - add_subtable -> add_to_subtable
607 # - del_subtable -> del_from_subtable
608 #
609 # Revision 1.21 2005/04/18 19:19:15 ncq
610 # - cleanup
611 #
612 # Revision 1.20 2005/04/14 18:58:59 cfmoro
613 # Commented line to avoid hiding _subtables
614 #
615 # Revision 1.19 2005/04/11 17:55:10 ncq
616 # - update self.original_payload in the right places
617 #
618 # Revision 1.18 2005/03/20 16:49:56 ncq
619 # - improve concurrency error handling docs
620 #
621 # Revision 1.17 2005/03/14 14:31:17 ncq
622 # - add support for self.original_payload such that we can make
623 # available all the information to the user when concurrency
624 # conflicts are detected
625 # - init _subtables so child classes don't HAVE to have it
626 #
627 # Revision 1.16 2005/03/06 21:15:13 ihaywood
628 # coment expanded on _subtables
629 #
630 # Revision 1.15 2005/03/06 14:44:02 ncq
631 # - cleanup
632 #
633 # Revision 1.14 2005/03/06 08:17:02 ihaywood
634 # forms: back to the old way, with support for LaTeX tables
635 #
636 # business objects now support generic linked tables, demographics
637 # uses them to the same functionality as before (loading, no saving)
638 # They may have no use outside of demographics, but saves much code already.
639 #
640 # Revision 1.13 2005/02/03 20:20:14 ncq
641 # - really use class level static connection pool
642 #
643 # Revision 1.12 2005/02/01 10:16:07 ihaywood
644 # refactoring of gmDemographicRecord and follow-on changes as discussed.
645 #
646 # gmTopPanel moves to gmHorstSpace
647 # gmRichardSpace added -- example code at present, haven't even run it myself
648 # (waiting on some icon .pngs from Richard)
649 #
650 # Revision 1.11 2005/01/31 12:56:55 ncq
651 # - properly update xmin in save_payload()
652 #
653 # Revision 1.10 2005/01/31 06:25:35 ncq
654 # - brown paper bag bug, I wonder how it ever worked:
655 # connections are gotten from an instance of the pool
656 #
657 # Revision 1.9 2005/01/19 06:52:24 ncq
658 # - improved docstring
659 #
660 # Revision 1.8 2005/01/02 19:58:02 ncq
661 # - remove _xmins_refetch_col_pos
662 #
663 # Revision 1.7 2005/01/02 16:16:52 ncq
664 # - by Ian: improve XMIN update on save by using new commit() get_col_idx
665 #
666 # Revision 1.6 2004/12/20 16:46:55 ncq
667 # - improve docs
668 # - close last known concurrency issue (reget xmin values after save)
669 #
670 # Revision 1.5 2004/12/17 16:15:36 ncq
671 # - add extension method result caching as suggested by Ian
672 # - I maintain a bad feeling due to cache eviction policy being murky at best
673 #
674 # Revision 1.4 2004/11/03 22:30:35 ncq
675 # - improved docs
676 # - introduce class level SQL query _cmds_lock_rows_for_update
677 # - rewrite save_payload() to use that via gmPG.run_commit2()
678 # - report concurrency errors from save_payload()
679 #
680 # Revision 1.3 2004/10/27 12:13:37 ncq
681 # - __init_from_row_data -> _init_from_row_data so we can override it
682 # - more sanity checks
683 #
684 # Revision 1.2 2004/10/12 18:37:45 ncq
685 # - Carlos added passing in possibly bulk-fetched row data w/o
686 # touching the database in __init__()
687 # - note that some higher level things will be broken until all
688 # affected child classes are fixed
689 # - however, note that child classes that don't overload __init__()
690 # are NOT affected and support no-DB init transparently
691 # - changed docs accordingly
692 # - this is the initial bulk-loader work that is hoped to gain
693 # quite some performance in some areas (think lab results)
694 #
695 # Revision 1.1 2004/10/11 19:05:41 ncq
696 # - business object-in-db root class, used by cClinItem etc.
697 #
698 # Revision 1.17 2004/06/18 13:31:21 ncq
699 # - return False from save_payload on failure to update
700 #
701 # Revision 1.16 2004/06/02 21:50:32 ncq
702 # - much improved error logging in set/getitem()
703 #
704 # Revision 1.15 2004/06/02 12:51:47 ncq
705 # - add exceptions tailored to cClinItem __set/getitem__()
706 # errors as per Syan's suggestion
707 #
708 # Revision 1.14 2004/05/22 08:09:10 ncq
709 # - more in line w/ coding style
710 # - _service will never change (or else it wouldn't
711 # be cCLINitem) but it's still good coding practice
712 # to put it into a class attribute
713 #
714 # Revision 1.13 2004/05/21 15:36:51 sjtan
715 #
716 # moved 'historica' into the class attribute SERVICE , in case gmClinItem can
717 # be reused in other services.
718 #
719 # Revision 1.12 2004/05/12 14:28:53 ncq
720 # - allow dict style pk definition in __init__ for multicolum primary keys (think views)
721 # - self.pk -> self.pk_obj
722 # - __init__(aPKey) -> __init__(aPK_obj)
723 #
724 # Revision 1.11 2004/05/08 22:13:11 ncq
725 # - cleanup
726 #
727 # Revision 1.10 2004/05/08 17:27:21 ncq
728 # - speed up __del__
729 # - use NoSuchClinItemError
730 #
731 # Revision 1.9 2004/04/20 13:32:33 ncq
732 # - improved __str__ output
733 #
734 # Revision 1.8 2004/04/19 12:41:30 ncq
735 # - self-check in __del__
736 #
737 # Revision 1.7 2004/04/18 18:50:36 ncq
738 # - override __init__() thusly removing the unholy _pre/post_init() business
739 #
740 # Revision 1.6 2004/04/18 17:51:28 ncq
741 # - it's surely helpful to be able to say <item>.is_modified() and know the status...
742 #
743 # Revision 1.5 2004/04/16 12:46:35 ncq
744 # - set is_modified=False after save_payload
745 #
746 # Revision 1.4 2004/04/16 00:00:59 ncq
747 # - Carlos fixes
748 # - save_payload should now work
749 #
750 # Revision 1.3 2004/04/12 22:53:19 ncq
751 # - __init__ now handles arbitrary keyword args
752 # - _pre_/_post_init()
753 # - streamline
754 # - must do _payload[self._idx[attribute]] since payload not a dict
755 #
756 # Revision 1.2 2004/04/11 11:24:00 ncq
757 # - handle _is_modified
758 # - protect against reload if modified
759 #
760 # Revision 1.1 2004/04/11 10:16:53 ncq
761 # - first version
762 #
763
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