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# Database access
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import copy
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import re
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import warnings
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import exc
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import dicts
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import iters
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from Proxy import Proxy
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import rand
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import strings
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import util
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##### Exceptions
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def get_cur_query(cur):
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if hasattr(cur, 'query'): return cur.query
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elif hasattr(cur, '_last_executed'): return cur._last_executed
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else: return None
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300
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def _add_cursor_info(e, cur): exc.add_msg(e, 'query: '+get_cur_query(cur))
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class DbException(exc.ExceptionWithCause):
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def __init__(self, msg, cause=None, cur=None):
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exc.ExceptionWithCause.__init__(self, msg, cause)
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if cur != None: _add_cursor_info(self, cur)
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class NameException(DbException): pass
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468
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class ExceptionWithColumns(DbException):
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def __init__(self, cols, cause=None):
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DbException.__init__(self, 'columns: ' + ', '.join(cols), cause)
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self.cols = cols
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class DuplicateKeyException(ExceptionWithColumns): pass
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class NullValueException(ExceptionWithColumns): pass
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class EmptyRowException(DbException): pass
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##### Warnings
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class DbWarning(UserWarning): pass
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##### Database connections
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db_config_names = ['engine', 'host', 'user', 'password', 'database']
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db_engines = {
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'MySQL': ('MySQLdb', {'password': 'passwd', 'database': 'db'}),
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'PostgreSQL': ('psycopg2', {}),
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}
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DatabaseErrors_set = set([DbException])
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DatabaseErrors = tuple(DatabaseErrors_set)
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def _add_module(module):
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DatabaseErrors_set.add(module.DatabaseError)
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global DatabaseErrors
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DatabaseErrors = tuple(DatabaseErrors_set)
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def db_config_str(db_config):
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return db_config['engine']+' database '+db_config['database']
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def _query_lookup(query, params): return (query, dicts.make_hashable(params))
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log_debug_none = lambda msg: None
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class DbConn:
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def __init__(self, db_config, serializable=True, log_debug=log_debug_none):
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self.db_config = db_config
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self.serializable = serializable
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self.log_debug = log_debug
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self.__db = None
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self.query_results = {}
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def __getattr__(self, name):
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if name == '__dict__': raise Exception('getting __dict__')
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if name == 'db': return self._db()
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else: raise AttributeError()
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def __getstate__(self):
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state = copy.copy(self.__dict__) # shallow copy
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state['log_debug'] = None # don't pickle the debug callback
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state['_DbConn__db'] = None # don't pickle the connection
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return state
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def _db(self):
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if self.__db == None:
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# Process db_config
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db_config = self.db_config.copy() # don't modify input!
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module_name, mappings = db_engines[db_config.pop('engine')]
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module = __import__(module_name)
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_add_module(module)
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for orig, new in mappings.iteritems():
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try: util.rename_key(db_config, orig, new)
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except KeyError: pass
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# Connect
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self.__db = module.connect(**db_config)
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# Configure connection
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if self.serializable: run_raw_query(self,
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'SET TRANSACTION ISOLATION LEVEL SERIALIZABLE')
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return self.__db
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class DbCursor(Proxy):
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def __init__(self, outer):
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Proxy.__init__(self, outer.db.cursor())
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self.query_results = outer.query_results
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self.query_lookup = None
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self.result = []
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def execute(self, query, params=None):
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self.query_lookup = _query_lookup(query, params)
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try: return_value = self.inner.execute(query, params)
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except Exception, e:
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self.result = e # cache the exception as the result
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self._cache_result()
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raise
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finally: self.query = get_cur_query(self.inner)
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return return_value
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def fetchone(self):
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row = self.inner.fetchone()
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if row != None: self.result.append(row)
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# otherwise, fetched all rows
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else: self._cache_result()
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return row
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def _cache_result(self):
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1906
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is_insert = self._is_insert()
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# For inserts, only cache exceptions since inserts are not
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# idempotent, but an invalid insert will always be invalid
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if self.query_results != None and (not is_insert
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or isinstance(self.result, Exception)):
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assert self.query_lookup != None
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1916
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self.query_results[self.query_lookup] = self.CacheCursor(
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util.dict_subset(dicts.AttrsDictView(self),
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['query', 'result', 'rowcount', 'description']))
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def _is_insert(self): return self.query.upper().find('INSERT') >= 0
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1916
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class CacheCursor:
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def __init__(self, cached_result): self.__dict__ = cached_result
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1927
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def execute(self, *args, **kw_args):
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1916
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if isinstance(self.result, Exception): raise self.result
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# otherwise, result is a rows list
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self.iter = iter(self.result)
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def fetchone(self):
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try: return self.iter.next()
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except StopIteration: return None
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1891
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aaronmk
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1894
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def run_query(self, query, params=None, cacheable=False):
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1903
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used_cache = False
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try:
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1927
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# Get cursor
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if cacheable:
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query_lookup = _query_lookup(query, params)
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try:
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cur = self.query_results[query_lookup]
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used_cache = True
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except KeyError: cur = self.DbCursor(self)
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else: cur = self.db.cursor()
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# Run query
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try: cur.execute(query, params)
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except Exception, e:
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_add_cursor_info(e, cur)
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raise
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| 177 |
1903
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aaronmk
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finally:
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if self.log_debug != log_debug_none: # only compute msg if needed
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if used_cache: cache_status = 'Cache hit'
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elif cacheable: cache_status = 'Cache miss'
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else: cache_status = 'Non-cacheable'
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1927
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aaronmk
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self.log_debug(cache_status+': '
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+strings.one_line(get_cur_query(cur)))
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| 184 |
1903
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aaronmk
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return cur
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| 186 |
1914
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aaronmk
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def is_cached(self, query, params=None):
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return _query_lookup(query, params) in self.query_results
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| 189 |
1849
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aaronmk
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1869
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connect = DbConn
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| 191 |
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| 192 |
1919
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aaronmk
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##### Input validation
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def check_name(name):
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if re.search(r'\W', name) != None: raise NameException('Name "'+name
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+'" may contain only alphanumeric characters and _')
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def esc_name_by_module(module, name, preserve_case=False):
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if module == 'psycopg2':
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if preserve_case: quote = '"'
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# Don't enclose in quotes because this disables case-insensitivity
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else: return name
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elif module == 'MySQLdb': quote = '`'
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else: raise NotImplementedError("Can't escape name for "+module+' database')
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return quote + name.replace(quote, '') + quote
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def esc_name_by_engine(engine, name, **kw_args):
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return esc_name_by_module(db_engines[engine][0], name, **kw_args)
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def esc_name(db, name, **kw_args):
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return esc_name_by_module(util.root_module(db.db), name, **kw_args)
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| 213 |
832
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aaronmk
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##### Querying
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| 215 |
1894
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aaronmk
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def run_raw_query(db, *args, **kw_args):
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| 216 |
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'''For args, see DbConn.run_query()'''
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| 217 |
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return db.run_query(*args, **kw_args)
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| 218 |
11
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aaronmk
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| 219 |
832
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aaronmk
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##### Recoverable querying
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| 220 |
15
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aaronmk
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| 221 |
11
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aaronmk
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def with_savepoint(db, func):
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| 222 |
1872
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aaronmk
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savepoint = 'savepoint_'+str(rand.rand_int()) # must be unique
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| 223 |
830
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aaronmk
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run_raw_query(db, 'SAVEPOINT '+savepoint)
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| 224 |
11
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aaronmk
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try: return_val = func()
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| 225 |
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except:
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| 226 |
830
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aaronmk
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run_raw_query(db, 'ROLLBACK TO SAVEPOINT '+savepoint)
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| 227 |
11
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aaronmk
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raise
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| 228 |
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else:
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| 229 |
830
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aaronmk
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run_raw_query(db, 'RELEASE SAVEPOINT '+savepoint)
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| 230 |
11
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aaronmk
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return return_val
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| 231 |
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| 232 |
1894
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aaronmk
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def run_query(db, query, params=None, recover=None, cacheable=False):
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| 233 |
830
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aaronmk
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if recover == None: recover = False
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| 234 |
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| 235 |
1894
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aaronmk
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def run(): return run_raw_query(db, query, params, cacheable)
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| 236 |
1914
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aaronmk
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if recover and not db.is_cached(query, params):
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| 237 |
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return with_savepoint(db, run)
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| 238 |
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else: return run() # don't need savepoint if cached
|
| 239 |
830
|
aaronmk
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| 240 |
832
|
aaronmk
|
##### Result retrieval
|
| 241 |
|
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| 242 |
1135
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aaronmk
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def col_names(cur): return (col[0] for col in cur.description)
|
| 243 |
832
|
aaronmk
|
|
| 244 |
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def rows(cur): return iter(lambda: cur.fetchone(), None)
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| 245 |
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|
| 246 |
1893
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aaronmk
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def next_row(cur): return rows(cur).next()
|
| 247 |
832
|
aaronmk
|
|
| 248 |
1893
|
aaronmk
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def row(cur):
|
| 249 |
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row_iter = rows(cur)
|
| 250 |
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row_ = row_iter.next()
|
| 251 |
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iters.consume_iter(row_iter) # fetch all rows so result will be cached
|
| 252 |
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return row_
|
| 253 |
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| 254 |
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def next_value(cur): return next_row(cur)[0]
|
| 255 |
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|
| 256 |
832
|
aaronmk
|
def value(cur): return row(cur)[0]
|
| 257 |
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| 258 |
1893
|
aaronmk
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def values(cur): return iters.func_iter(lambda: next_value(cur))
|
| 259 |
832
|
aaronmk
|
|
| 260 |
|
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def value_or_none(cur):
|
| 261 |
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try: return value(cur)
|
| 262 |
|
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except StopIteration: return None
|
| 263 |
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| 264 |
|
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##### Basic queries
|
| 265 |
|
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|
| 266 |
1135
|
aaronmk
|
def select(db, table, fields=None, conds=None, limit=None, start=None,
|
| 267 |
1894
|
aaronmk
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recover=None, cacheable=True):
|
| 268 |
1135
|
aaronmk
|
'''@param fields Use None to select all fields in the table'''
|
| 269 |
|
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if conds == None: conds = {}
|
| 270 |
135
|
aaronmk
|
assert limit == None or type(limit) == int
|
| 271 |
865
|
aaronmk
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assert start == None or type(start) == int
|
| 272 |
15
|
aaronmk
|
check_name(table)
|
| 273 |
1135
|
aaronmk
|
if fields != None: map(check_name, fields)
|
| 274 |
15
|
aaronmk
|
map(check_name, conds.keys())
|
| 275 |
865
|
aaronmk
|
|
| 276 |
11
|
aaronmk
|
def cond(entry):
|
| 277 |
13
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aaronmk
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col, value = entry
|
| 278 |
644
|
aaronmk
|
cond_ = esc_name(db, col)+' '
|
| 279 |
11
|
aaronmk
|
if value == None: cond_ += 'IS'
|
| 280 |
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else: cond_ += '='
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| 281 |
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cond_ += ' %s'
|
| 282 |
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return cond_
|
| 283 |
1135
|
aaronmk
|
query = 'SELECT '
|
| 284 |
|
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if fields == None: query += '*'
|
| 285 |
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else: query += ', '.join([esc_name(db, field) for field in fields])
|
| 286 |
|
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query += ' FROM '+esc_name(db, table)
|
| 287 |
865
|
aaronmk
|
|
| 288 |
|
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missing = True
|
| 289 |
89
|
aaronmk
|
if conds != {}:
|
| 290 |
|
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query += ' WHERE '+' AND '.join(map(cond, conds.iteritems()))
|
| 291 |
865
|
aaronmk
|
missing = False
|
| 292 |
|
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if limit != None: query += ' LIMIT '+str(limit); missing = False
|
| 293 |
|
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if start != None:
|
| 294 |
|
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if start != 0: query += ' OFFSET '+str(start)
|
| 295 |
|
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missing = False
|
| 296 |
|
|
if missing: warnings.warn(DbWarning(
|
| 297 |
|
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'SELECT statement missing a WHERE, LIMIT, or OFFSET clause: '+query))
|
| 298 |
|
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|
| 299 |
1905
|
aaronmk
|
return run_query(db, query, conds.values(), recover, cacheable)
|
| 300 |
11
|
aaronmk
|
|
| 301 |
1905
|
aaronmk
|
def insert(db, table, row, returning=None, recover=None, cacheable=True):
|
| 302 |
1554
|
aaronmk
|
'''@param returning str|None An inserted column (such as pkey) to return'''
|
| 303 |
11
|
aaronmk
|
check_name(table)
|
| 304 |
13
|
aaronmk
|
cols = row.keys()
|
| 305 |
15
|
aaronmk
|
map(check_name, cols)
|
| 306 |
89
|
aaronmk
|
query = 'INSERT INTO '+table
|
| 307 |
1554
|
aaronmk
|
|
| 308 |
89
|
aaronmk
|
if row != {}: query += ' ('+', '.join(cols)+') VALUES ('\
|
| 309 |
|
|
+', '.join(['%s']*len(cols))+')'
|
| 310 |
|
|
else: query += ' DEFAULT VALUES'
|
| 311 |
1554
|
aaronmk
|
|
| 312 |
|
|
if returning != None:
|
| 313 |
|
|
check_name(returning)
|
| 314 |
|
|
query += ' RETURNING '+returning
|
| 315 |
|
|
|
| 316 |
1905
|
aaronmk
|
return run_query(db, query, row.values(), recover, cacheable)
|
| 317 |
11
|
aaronmk
|
|
| 318 |
135
|
aaronmk
|
def last_insert_id(db):
|
| 319 |
1849
|
aaronmk
|
module = util.root_module(db.db)
|
| 320 |
135
|
aaronmk
|
if module == 'psycopg2': return value(run_query(db, 'SELECT lastval()'))
|
| 321 |
|
|
elif module == 'MySQLdb': return db.insert_id()
|
| 322 |
|
|
else: return None
|
| 323 |
13
|
aaronmk
|
|
| 324 |
832
|
aaronmk
|
def truncate(db, table):
|
| 325 |
|
|
check_name(table)
|
| 326 |
869
|
aaronmk
|
return run_raw_query(db, 'TRUNCATE '+table+' CASCADE')
|
| 327 |
832
|
aaronmk
|
|
| 328 |
|
|
##### Database structure queries
|
| 329 |
|
|
|
| 330 |
1850
|
aaronmk
|
def pkey(db, table, recover=None):
|
| 331 |
832
|
aaronmk
|
'''Assumed to be first column in table'''
|
| 332 |
|
|
check_name(table)
|
| 333 |
1915
|
aaronmk
|
return col_names(run_query(db,
|
| 334 |
|
|
'SELECT * FROM '+table+' LIMIT 0', recover=recover)).next()
|
| 335 |
832
|
aaronmk
|
|
| 336 |
853
|
aaronmk
|
def index_cols(db, table, index):
|
| 337 |
|
|
'''Can also use this for UNIQUE constraints, because a UNIQUE index is
|
| 338 |
|
|
automatically created. When you don't know whether something is a UNIQUE
|
| 339 |
|
|
constraint or a UNIQUE index, use this function.'''
|
| 340 |
|
|
check_name(table)
|
| 341 |
|
|
check_name(index)
|
| 342 |
1909
|
aaronmk
|
module = util.root_module(db.db)
|
| 343 |
|
|
if module == 'psycopg2':
|
| 344 |
|
|
return list(values(run_query(db, '''\
|
| 345 |
853
|
aaronmk
|
SELECT attname
|
| 346 |
866
|
aaronmk
|
FROM
|
| 347 |
|
|
(
|
| 348 |
|
|
SELECT attnum, attname
|
| 349 |
|
|
FROM pg_index
|
| 350 |
|
|
JOIN pg_class index ON index.oid = indexrelid
|
| 351 |
|
|
JOIN pg_class table_ ON table_.oid = indrelid
|
| 352 |
|
|
JOIN pg_attribute ON attrelid = indrelid AND attnum = ANY (indkey)
|
| 353 |
|
|
WHERE
|
| 354 |
|
|
table_.relname = %(table)s
|
| 355 |
|
|
AND index.relname = %(index)s
|
| 356 |
|
|
UNION
|
| 357 |
|
|
SELECT attnum, attname
|
| 358 |
|
|
FROM
|
| 359 |
|
|
(
|
| 360 |
|
|
SELECT
|
| 361 |
|
|
indrelid
|
| 362 |
|
|
, (regexp_matches(indexprs, E':varattno (\\\\d+)', 'g'))[1]::int
|
| 363 |
|
|
AS indkey
|
| 364 |
|
|
FROM pg_index
|
| 365 |
|
|
JOIN pg_class index ON index.oid = indexrelid
|
| 366 |
|
|
JOIN pg_class table_ ON table_.oid = indrelid
|
| 367 |
|
|
WHERE
|
| 368 |
|
|
table_.relname = %(table)s
|
| 369 |
|
|
AND index.relname = %(index)s
|
| 370 |
|
|
) s
|
| 371 |
|
|
JOIN pg_attribute ON attrelid = indrelid AND attnum = indkey
|
| 372 |
|
|
) s
|
| 373 |
853
|
aaronmk
|
ORDER BY attnum
|
| 374 |
|
|
''',
|
| 375 |
1909
|
aaronmk
|
{'table': table, 'index': index}, cacheable=True)))
|
| 376 |
|
|
else: raise NotImplementedError("Can't list index columns for "+module+
|
| 377 |
|
|
' database')
|
| 378 |
853
|
aaronmk
|
|
| 379 |
464
|
aaronmk
|
def constraint_cols(db, table, constraint):
|
| 380 |
|
|
check_name(table)
|
| 381 |
|
|
check_name(constraint)
|
| 382 |
1849
|
aaronmk
|
module = util.root_module(db.db)
|
| 383 |
464
|
aaronmk
|
if module == 'psycopg2':
|
| 384 |
|
|
return list(values(run_query(db, '''\
|
| 385 |
|
|
SELECT attname
|
| 386 |
|
|
FROM pg_constraint
|
| 387 |
|
|
JOIN pg_class ON pg_class.oid = conrelid
|
| 388 |
|
|
JOIN pg_attribute ON attrelid = conrelid AND attnum = ANY (conkey)
|
| 389 |
|
|
WHERE
|
| 390 |
|
|
relname = %(table)s
|
| 391 |
|
|
AND conname = %(constraint)s
|
| 392 |
|
|
ORDER BY attnum
|
| 393 |
|
|
''',
|
| 394 |
|
|
{'table': table, 'constraint': constraint})))
|
| 395 |
|
|
else: raise NotImplementedError("Can't list constraint columns for "+module+
|
| 396 |
|
|
' database')
|
| 397 |
|
|
|
| 398 |
832
|
aaronmk
|
def tables(db):
|
| 399 |
1849
|
aaronmk
|
module = util.root_module(db.db)
|
| 400 |
832
|
aaronmk
|
if module == 'psycopg2':
|
| 401 |
|
|
return values(run_query(db, "SELECT tablename from pg_tables "
|
| 402 |
|
|
"WHERE schemaname = 'public' ORDER BY tablename"))
|
| 403 |
|
|
elif module == 'MySQLdb': return values(run_query(db, 'SHOW TABLES'))
|
| 404 |
|
|
else: raise NotImplementedError("Can't list tables for "+module+' database')
|
| 405 |
830
|
aaronmk
|
|
| 406 |
833
|
aaronmk
|
##### Database management
|
| 407 |
|
|
|
| 408 |
|
|
def empty_db(db):
|
| 409 |
|
|
for table in tables(db): truncate(db, table)
|
| 410 |
|
|
|
| 411 |
832
|
aaronmk
|
##### Heuristic queries
|
| 412 |
|
|
|
| 413 |
1554
|
aaronmk
|
def try_insert(db, table, row, returning=None):
|
| 414 |
830
|
aaronmk
|
'''Recovers from errors'''
|
| 415 |
1554
|
aaronmk
|
try: return insert(db, table, row, returning, recover=True)
|
| 416 |
46
|
aaronmk
|
except Exception, e:
|
| 417 |
|
|
msg = str(e)
|
| 418 |
465
|
aaronmk
|
match = re.search(r'duplicate key value violates unique constraint '
|
| 419 |
|
|
r'"(([^\W_]+)_[^"]+)"', msg)
|
| 420 |
|
|
if match:
|
| 421 |
|
|
constraint, table = match.groups()
|
| 422 |
854
|
aaronmk
|
try: cols = index_cols(db, table, constraint)
|
| 423 |
465
|
aaronmk
|
except NotImplementedError: raise e
|
| 424 |
851
|
aaronmk
|
else: raise DuplicateKeyException(cols, e)
|
| 425 |
13
|
aaronmk
|
match = re.search(r'null value in column "(\w+)" violates not-null '
|
| 426 |
|
|
'constraint', msg)
|
| 427 |
470
|
aaronmk
|
if match: raise NullValueException([match.group(1)], e)
|
| 428 |
13
|
aaronmk
|
raise # no specific exception raised
|
| 429 |
11
|
aaronmk
|
|
| 430 |
471
|
aaronmk
|
def put(db, table, row, pkey, row_ct_ref=None):
|
| 431 |
1554
|
aaronmk
|
'''Recovers from errors.
|
| 432 |
|
|
Only works under PostgreSQL (uses `INSERT ... RETURNING`)'''
|
| 433 |
471
|
aaronmk
|
try:
|
| 434 |
1554
|
aaronmk
|
cur = try_insert(db, table, row, pkey)
|
| 435 |
|
|
if row_ct_ref != None and cur.rowcount >= 0:
|
| 436 |
|
|
row_ct_ref[0] += cur.rowcount
|
| 437 |
|
|
return value(cur)
|
| 438 |
471
|
aaronmk
|
except DuplicateKeyException, e:
|
| 439 |
1069
|
aaronmk
|
return value(select(db, table, [pkey],
|
| 440 |
|
|
util.dict_subset_right_join(row, e.cols), recover=True))
|
| 441 |
471
|
aaronmk
|
|
| 442 |
473
|
aaronmk
|
def get(db, table, row, pkey, row_ct_ref=None, create=False):
|
| 443 |
830
|
aaronmk
|
'''Recovers from errors'''
|
| 444 |
|
|
try: return value(select(db, table, [pkey], row, 1, recover=True))
|
| 445 |
14
|
aaronmk
|
except StopIteration:
|
| 446 |
40
|
aaronmk
|
if not create: raise
|
| 447 |
471
|
aaronmk
|
return put(db, table, row, pkey, row_ct_ref) # insert new row
|
