__init__.py

   1 from __future__ import unicode_literals
   2 from __future__ import print_function
   3
   4 import inspect
   5 import os
   6
   7 from contextlib import contextmanager
   8
   9 import psycopg2
  10 import psycopg2.extras
  11 import psycopg2.pool
  12
  13 psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
  14
  15 class connection(object):
  16     def __init__(self, driver):
  17         self.driver = driver
  18
  19     @contextmanager
  20     def cursor(self):
  21         try:
  22             cursor = self.driver.cursor(cursor_factory=psycopg2.extras.DictCursor)
  23             yield cursor
  24         finally:
  25             cursor.close()
  26
  27     @contextmanager
  28     def execute_(self, statement, locals):
  29         with self.cursor() as cursor:
  30             cursor.execute(statement.format(**locals), locals)
  31             yield cursor
  32
  33     @contextmanager
  34     def execute(self, statement, depth=0, context=None):
  35         with self.cursor() as cursor:
  36             # two frames, accounting for execute() and @contextmanager
  37             locals = inspect.currentframe(depth + 2).f_locals
  38             try:
  39                 if context == None:
  40                     context = locals
  41                 cursor.execute(statement.format(**locals), context)
  42             finally:
  43                 del locals
  44             yield cursor
  45
  46     @contextmanager
  47     def transact(self, synchronous_commit=True):
  48         with self.cursor() as cursor:
  49             if not synchronous_commit:
  50                 cursor.execute('set local synchronous_commit = off')
  51
  52         try:
  53             yield transaction(self)
  54             self.driver.commit()
  55         except:
  56             self.driver.rollback()
  57             raise
  58
  59 class transaction(object):
  60     def __init__(self, connection):
  61         self.connection = connection
  62
  63     def pull(self, statement):
  64         with self.connection.execute(statement, 1) as cursor:
  65             return cursor.fetchall()
  66
  67     def yank(self, statement, offset=0):
  68         with self.connection.execute(statement, 1 + offset) as cursor:
  69             rows = cursor.fetchall()
  70             return rows[0] if len(rows) != 0 else None
  71
  72     def push(self, statement):
  73         with self.connection.execute(statement, 1) as cursor:
  74             pass
  75
  76     def push_(self, statement, locals):
  77         with self.connection.execute_(statement, locals) as cursor:
  78             pass
  79
  80     def exists(self, statement):
  81         return self.yank('''
  82             select exists (
  83                 {statement}
  84             )
  85         '''.format(**locals()), 1)[0]
  86
  87 @contextmanager
  88 def connect(dsn):
  89     attempt = 0
  90     while True:
  91         try:
  92             driver = psycopg2.connect(**dsn)
  93             break
  94         except psycopg2.OperationalError, e:
  95             if attempt == 2:
  96                 raise e
  97             attempt = attempt + 1
  98
  99     try:
 100         driver.set_client_encoding('UNICODE')
 101         yield connection(driver)
 102     finally:
 103         driver.close()
 104
 105 def connected(dsn):
 106     def wrapped(method):
 107         def replaced(*args, **kw):
 108             with connect(dsn) as connection:
 109                 return method(connection, *args, **kw)
 110         return replaced
 111     return wrapped
 112
 113 @contextmanager
 114 def transact(dsn, **args):
 115     with connect(dsn) as connection:
 116         with connection.transact(**args) as cursor:
 117             yield cursor
 118
 119 """
 120 def slap_(sql, table, keys, values, path):
 121     csr = sql.cursor()
 122     try:
 123         csr.execute('savepoint iou')
 124         try:
 125             both = dict(keys, **values)
 126             fields = both.keys()
 127
 128             csr.execute('''
 129                 insert into %s (%s) values (%s)
 130             ''' % (
 131                 table,
 132                 ', '.join(fields),
 133                 ', '.join(['%s' for key in fields])
 134             ), both.values())
 135         except psycopg2.IntegrityError, e:
 136             csr.execute('rollback to savepoint iou')
 137
 138             csr.execute('''
 139                 update %s set %s where %s
 140             ''' % (
 141                 table,
 142                 ', '.join([
 143                     key + ' = %s'
 144                 for key in values.keys()]),
 145                 ' and '.join([
 146                     key + ' = %s'
 147                 for key in keys.keys()])
 148             ), values.values() + keys.values())
 149
 150         return path_(csr, path)
 151     finally:
 152         csr.close()
 153 """