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 __version__ = "$Revision: 1.60 $"
129 __author__ = "K.Hilbert <Karsten.Hilbert@gmx.net>"
130 __license__ = "GPL"
131
132 import sys, copy, types, inspect, logging, datetime
133
134
135 if __name__ == '__main__':
136 sys.path.insert(0, '../../')
137 from Gnumed.pycommon import gmExceptions, gmPG2
138
139
140 _log = logging.getLogger('gm.db')
141 _log.info(__version__)
142
144 """Represents business objects in the database.
145
146 Rules:
147 - instances ARE ASSUMED TO EXIST in the database
148 - PK construction (aPK_obj): DOES verify its existence on instantiation
149 (fetching data fails)
150 - Row construction (row): allowed by using a dict of pairs
151 field name: field value (PERFORMANCE improvement)
152 - does NOT verify FK target existence
153 - does NOT create new entries in the database
154 - does NOT lazy-fetch fields on access
155
156 Class scope SQL commands and variables:
157
158 <_cmd_fetch_payload>
159 - must return exactly one row
160 - where clause argument values are expected
161 in self.pk_obj (taken from __init__(aPK_obj))
162 - must return xmin of all rows that _cmds_store_payload
163 will be updating, so views must support the xmin columns
164 of their underlying tables
165
166 <_cmds_store_payload>
167 - one or multiple "update ... set ... where xmin_* = ..." statements
168 which actually update the database from the data in self._payload,
169 - the last query must refetch at least the XMIN values needed to detect
170 concurrent updates, their field names had better be the same as
171 in _cmd_fetch_payload,
172 - when subclasses tend to live a while after save_payload() was
173 called and they support computed fields (say, _(some_column)
174 you need to return *all* columns (see cEncounter)
175
176 <_updatable_fields>
177 - a list of fields available for update via object['field']
178
179
180 A template for new child classes:
181
182 *********** start of template ***********
183
184 #------------------------------------------------------------
185 from Gnumed.pycommon import gmBusinessDBObject
186 from Gnumed.pycommon import gmPG2
187
188 #============================================================
189 # short description
190 #------------------------------------------------------------
191 # use plural form, search-replace get_XXX
192 _SQL_get_XXX = u\"""
193 SELECT *, (xmin AS xmin_XXX)
194 FROM XXX.v_XXX
195 WHERE %s
196 \"""
197
198 class cXxxXxx(gmBusinessDBObject.cBusinessDBObject):
199 \"""Represents ...\"""
200
201 _cmd_fetch_payload = _SQL_get_XXX % u"pk_XXX = %s"
202 _cmds_store_payload = [
203 u\"""
204 UPDATE xxx.xxx SET -- typically the underlying table name
205 xxx = %(xxx)s, -- typically "table_col = %(view_col)s"
206 xxx = gm.nullify_empty_string(%(xxx)s)
207 WHERE
208 pk = %(pk_XXX)s
209 AND
210 xmin = %(xmin_XXX)s
211 RETURNING
212 pk as pk_XXX,
213 xmin as xmin_XXX
214 \"""
215 ]
216 # view columns that can be updated:
217 _updatable_fields = [
218 u'xxx',
219 u'xxx'
220 ]
221 #------------------------------------------------------------
222 def get_XXX(order_by=None):
223 if order_by is None:
224 order_by = u'true'
225 else:
226 order_by = u'true ORDER BY %s' % order_by
227
228 cmd = _SQL_get_XXX % order_by
229 rows, idx = gmPG2.run_ro_queries(queries = [{'cmd': cmd}], get_col_idx = True)
230 return [ cXxxXxx(row = {'data': r, 'idx': idx, 'pk_field': 'xxx'}) for r in rows ]
231 #------------------------------------------------------------
232 def create_xxx(xxx=None, xxx=None):
233
234 args = {
235 u'xxx': xxx,
236 u'xxx': xxx
237 }
238 cmd = u\"""
239 INSERT INTO xxx.xxx (
240 xxx,
241 xxx,
242 xxx
243 ) VALUES (
244 %(xxx)s,
245 %(xxx)s,
246 gm.nullify_empty_string(%(xxx)s)
247 )
248 RETURNING pk
249 \"""
250 rows, idx = gmPG2.run_rw_queries(queries = [{'cmd': cmd, 'args': args}], return_data = True, get_col_idx = False)
251
252 return cXxxXxx(aPK_obj = rows[0]['pk'])
253 #------------------------------------------------------------
254 def delete_xxx(xxx=None):
255 args = {'pk': xxx}
256 cmd = u"DELETE FROM xxx.xxx WHERE pk = %(pk)s"
257 gmPG2.run_rw_queries(queries = [{'cmd': cmd, 'args': args}])
258 return True
259 #------------------------------------------------------------
260
261 *********** end of template ***********
262
263 """
264
265 - def __init__(self, aPK_obj=None, row=None):
266 """Init business object.
267
268 Call from child classes:
269
270 super(cChildClass, self).__init__(aPK_obj = aPK_obj, row = row)
271 """
272
273
274
275 self.pk_obj = '<uninitialized>'
276 self._idx = {}
277 self._payload = []
278 self._ext_cache = {}
279 self._is_modified = False
280
281
282 self.__class__._cmd_fetch_payload
283 self.__class__._cmds_store_payload
284 self.__class__._updatable_fields
285
286 if aPK_obj is not None:
287 self.__init_from_pk(aPK_obj=aPK_obj)
288 else:
289 self._init_from_row_data(row=row)
290
291 self._is_modified = False
292
294 """Creates a new clinical item instance by its PK.
295
296 aPK_obj can be:
297 - a simple value
298 * the primary key WHERE condition must be
299 a simple column
300 - a dictionary of values
301 * the primary key where condition must be a
302 subselect consuming the dict and producing
303 the single-value primary key
304 """
305 self.pk_obj = aPK_obj
306 result = self.refetch_payload()
307 if result is True:
308 self.original_payload = {}
309 for field in self._idx.keys():
310 self.original_payload[field] = self._payload[self._idx[field]]
311 return True
312
313 if result is False:
314 raise gmExceptions.ConstructorError, "[%s:%s]: error loading instance" % (self.__class__.__name__, self.pk_obj)
315
317 """Creates a new clinical item instance given its fields.
318
319 row must be a dict with the fields:
320 - pk_field: the name of the primary key field
321 - idx: a dict mapping field names to position
322 - data: the field values in a list (as returned by
323 cursor.fetchone() in the DB-API)
324
325 row = {'data': row, 'idx': idx, 'pk_field': 'the PK column name'}
326
327 rows, idx = gmPG2.run_ro_queries(queries = [{'cmd': cmd, 'args': args}], get_col_idx = True)
328 objects = [ cChildClass(row = {'data': r, 'idx': idx, 'pk_field': 'the PK column name'}) for r in rows ]
329 """
330 try:
331 self._idx = row['idx']
332 self._payload = row['data']
333 self.pk_obj = self._payload[self._idx[row['pk_field']]]
334 except:
335 _log.exception('faulty <row> argument structure: %s' % row)
336 raise gmExceptions.ConstructorError, "[%s:??]: error loading instance from row data" % self.__class__.__name__
337
338 if len(self._idx.keys()) != len(self._payload):
339 _log.critical('field index vs. payload length mismatch: %s field names vs. %s fields' % (len(self._idx.keys()), len(self._payload)))
340 _log.critical('faulty <row> argument structure: %s' % row)
341 raise gmExceptions.ConstructorError, "[%s:??]: error loading instance from row data" % self.__class__.__name__
342
343 self.original_payload = {}
344 for field in self._idx.keys():
345 self.original_payload[field] = self._payload[self._idx[field]]
346
348 if self.__dict__.has_key('_is_modified'):
349 if self._is_modified:
350 _log.critical('[%s:%s]: loosing payload changes' % (self.__class__.__name__, self.pk_obj))
351 _log.debug('original: %s' % self.original_payload)
352 _log.debug('modified: %s' % self._payload)
353
355 tmp = []
356 try:
357 for attr in self._idx.keys():
358 if self._payload[self._idx[attr]] is None:
359 tmp.append(u'%s: NULL' % attr)
360 else:
361 tmp.append('%s: >>%s<<' % (attr, self._payload[self._idx[attr]]))
362 return '[%s:%s]: %s' % (self.__class__.__name__, self.pk_obj, str(tmp))
363 except:
364 return 'nascent [%s @ %s], cannot show payload and primary key' %(self.__class__.__name__, id(self))
365
367
368
369
370 try:
371 return self._payload[self._idx[attribute]]
372 except KeyError:
373 pass
374
375
376 getter = getattr(self, 'get_%s' % attribute, None)
377 if not callable(getter):
378 _log.warning('[%s]: no attribute [%s]' % (self.__class__.__name__, attribute))
379 _log.warning('[%s]: valid attributes: %s' % (self.__class__.__name__, str(self._idx.keys())))
380 _log.warning('[%s]: no getter method [get_%s]' % (self.__class__.__name__, attribute))
381 methods = filter(lambda x: x[0].startswith('get_'), inspect.getmembers(self, inspect.ismethod))
382 _log.warning('[%s]: valid getter methods: %s' % (self.__class__.__name__, str(methods)))
383 raise KeyError('[%s]: cannot read from key [%s]' % (self.__class__.__name__, attribute))
384
385 self._ext_cache[attribute] = getter()
386 return self._ext_cache[attribute]
387
389
390
391 if attribute in self.__class__._updatable_fields:
392 try:
393 if self._payload[self._idx[attribute]] != value:
394 self._payload[self._idx[attribute]] = value
395 self._is_modified = True
396 return
397 except KeyError:
398 _log.warning('[%s]: cannot set attribute <%s> despite marked settable' % (self.__class__.__name__, attribute))
399 _log.warning('[%s]: supposedly settable attributes: %s' % (self.__class__.__name__, str(self.__class__._updatable_fields)))
400 raise KeyError('[%s]: cannot write to key [%s]' % (self.__class__.__name__, attribute))
401
402
403 if hasattr(self, 'set_%s' % attribute):
404 setter = getattr(self, "set_%s" % attribute)
405 if not callable(setter):
406 raise AttributeError('[%s] setter [set_%s] not callable' % (self.__class__.__name__, attribute))
407 try:
408 del self._ext_cache[attribute]
409 except KeyError:
410 pass
411 if type(value) is types.TupleType:
412 if setter(*value):
413 self._is_modified = True
414 return
415 raise AttributeError('[%s]: setter [%s] failed for [%s]' % (self.__class__.__name__, setter, value))
416 if setter(value):
417 self._is_modified = True
418 return
419
420
421 _log.error('[%s]: cannot find attribute <%s> or setter method [set_%s]' % (self.__class__.__name__, attribute, attribute))
422 _log.warning('[%s]: settable attributes: %s' % (self.__class__.__name__, str(self.__class__._updatable_fields)))
423 methods = filter(lambda x: x[0].startswith('set_'), inspect.getmembers(self, inspect.ismethod))
424 _log.warning('[%s]: valid setter methods: %s' % (self.__class__.__name__, str(methods)))
425 raise AttributeError('[%s]: cannot set [%s]' % (self.__class__.__name__, attribute))
426
427
428
430 raise NotImplementedError('comparison between [%s] and [%s] not implemented' % (self, another_object))
431
433 return self._is_modified
434
436 try:
437 return self._idx.keys()
438 except AttributeError:
439 return 'nascent [%s @ %s], cannot return keys' %(self.__class__.__name__, id(self))
440
443
445 _log.error('[%s:%s]: forgot to override get_patient()' % (self.__class__.__name__, self.pk_obj))
446 return None
447
449 """Fetch field values from backend.
450 """
451 if self._is_modified:
452 if ignore_changes:
453 _log.critical('[%s:%s]: loosing payload changes' % (self.__class__.__name__, self.pk_obj))
454 _log.debug('original: %s' % self.original_payload)
455 _log.debug('modified: %s' % self._payload)
456 else:
457 _log.critical('[%s:%s]: cannot reload, payload changed' % (self.__class__.__name__, self.pk_obj))
458 return False
459
460 if type(self.pk_obj) == types.DictType:
461 arg = self.pk_obj
462 else:
463 arg = [self.pk_obj]
464 rows, self._idx = gmPG2.run_ro_queries (
465 queries = [{'cmd': self.__class__._cmd_fetch_payload, 'args': arg}],
466 get_col_idx = True
467 )
468 if len(rows) == 0:
469 _log.error('[%s:%s]: no such instance' % (self.__class__.__name__, self.pk_obj))
470 return False
471 self._payload = rows[0]
472 return True
473
476
477 - def save(self, conn=None):
479
481 """Store updated values (if any) in database.
482
483 Optionally accepts a pre-existing connection
484 - returns a tuple (<True|False>, <data>)
485 - True: success
486 - False: an error occurred
487 * data is (error, message)
488 * for error meanings see gmPG2.run_rw_queries()
489 """
490 if not self._is_modified:
491 return (True, None)
492
493 args = {}
494 for field in self._idx.keys():
495 args[field] = self._payload[self._idx[field]]
496 self.modified_payload = args
497
498 close_conn = self.__noop
499 if conn is None:
500 conn = gmPG2.get_connection(readonly=False)
501 close_conn = conn.close
502
503
504
505
506
507
508 queries = []
509 for query in self.__class__._cmds_store_payload:
510 queries.append({'cmd': query, 'args': args})
511 rows, idx = gmPG2.run_rw_queries (
512 link_obj = conn,
513 queries = queries,
514 return_data = True,
515 get_col_idx = True
516 )
517
518
519
520
521
522 if len(rows) == 0:
523 return (False, (u'cannot update row', _('[%s:%s]: row not updated (nothing returned), row in use ?') % (self.__class__.__name__, self.pk_obj)))
524
525
526 row = rows[0]
527 for key in idx:
528 try:
529 self._payload[self._idx[key]] = row[idx[key]]
530 except KeyError:
531 conn.rollback()
532 close_conn()
533 _log.error('[%s:%s]: cannot update instance, XMIN refetch key mismatch on [%s]' % (self.__class__.__name__, self.pk_obj, key))
534 _log.error('payload keys: %s' % str(self._idx))
535 _log.error('XMIN refetch keys: %s' % str(idx))
536 _log.error(args)
537 raise
538
539 conn.commit()
540 close_conn()
541
542 self._is_modified = False
543
544 self.original_payload = {}
545 for field in self._idx.keys():
546 self.original_payload[field] = self._payload[self._idx[field]]
547
548 return (True, None)
549
550
552
553 """ turn the data into a list of dicts, adding "class hints".
554 all objects get turned into dictionaries which the other end
555 will interpret as "object", via the __jsonclass__ hint,
556 as specified by the JSONRPC protocol standard.
557 """
558 if isinstance(obj, list):
559 return map(jsonclasshintify, obj)
560 elif isinstance(obj, gmPG2.dbapi.tz.FixedOffsetTimezone):
561
562
563 res = {'__jsonclass__': ["jsonobjproxy.FixedOffsetTimezone"]}
564 res['name'] = obj._name
565 res['offset'] = jsonclasshintify(obj._offset)
566 return res
567 elif isinstance(obj, datetime.timedelta):
568
569
570 res = {'__jsonclass__': ["jsonobjproxy.TimeDelta"]}
571 res['days'] = obj.days
572 res['seconds'] = obj.seconds
573 res['microseconds'] = obj.microseconds
574 return res
575 elif isinstance(obj, datetime.time):
576
577
578 res = {'__jsonclass__': ["jsonobjproxy.Time"]}
579 res['hour'] = obj.hour
580 res['minute'] = obj.minute
581 res['second'] = obj.second
582 res['microsecond'] = obj.microsecond
583 res['tzinfo'] = jsonclasshintify(obj.tzinfo)
584 return res
585 elif isinstance(obj, datetime.datetime):
586
587
588 res = {'__jsonclass__': ["jsonobjproxy.DateTime"]}
589 res['year'] = obj.year
590 res['month'] = obj.month
591 res['day'] = obj.day
592 res['hour'] = obj.hour
593 res['minute'] = obj.minute
594 res['second'] = obj.second
595 res['microsecond'] = obj.microsecond
596 res['tzinfo'] = jsonclasshintify(obj.tzinfo)
597 return res
598 elif isinstance(obj, cBusinessDBObject):
599
600
601 res = {'__jsonclass__': ["jsonobjproxy.%s" % obj.__class__.__name__]}
602 for k in obj.get_fields():
603 t = jsonclasshintify(obj[k])
604 res[k] = t
605 print "props", res, dir(obj)
606 for attribute in dir(obj):
607 if not attribute.startswith("get_"):
608 continue
609 k = attribute[4:]
610 if res.has_key(k):
611 continue
612 getter = getattr(obj, attribute, None)
613 if callable(getter):
614 res[k] = jsonclasshintify(getter())
615 return res
616 return obj
617
618
619 if __name__ == '__main__':
620
621 if len(sys.argv) < 2:
622 sys.exit()
623
624 if sys.argv[1] != u'test':
625 sys.exit()
626
627
638
639 from Gnumed.pycommon import gmI18N
640 gmI18N.activate_locale()
641 gmI18N.install_domain()
642
643 data = {
644 'pk_field': 'bogus_pk',
645 'idx': {'bogus_pk': 0, 'bogus_field': 1},
646 'data': [-1, 'bogus_data']
647 }
648 obj = cTestObj(row=data)
649
650
651 obj['wrong_field'] = 1
652
653
654