code.grnet.gr Git - pithos/blob - snf-pithos-backend/pithos/backends/lib/sqlalchemy/xfeatures.py

   1 # Copyright 2011-2012 GRNET S.A. All rights reserved.
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  32 # or implied, of GRNET S.A.
  33
  34 from collections import defaultdict
  35 from sqlalchemy import Table, Column, String, Integer, MetaData, ForeignKey
  36 from sqlalchemy.sql import select, and_
  37 from sqlalchemy.schema import Index
  38 from sqlalchemy.sql.expression import desc
  39
  40 from dbworker import DBWorker
  41
  42
  43 class XFeatures(DBWorker):
  44     """XFeatures are path properties that allow non-nested
  45        inheritance patterns. Currently used for storing permissions.
  46     """
  47
  48     def __init__(self, **params):
  49         DBWorker.__init__(self, **params)
  50         metadata = MetaData()
  51         columns=[]
  52         columns.append(Column('feature_id', Integer, primary_key=True))
  53         columns.append(Column('path', String(2048)))
  54         self.xfeatures = Table('xfeatures', metadata, *columns, mysql_engine='InnoDB')
  55         # place an index on path
  56         Index('idx_features_path', self.xfeatures.c.path, unique=True)
  57
  58         columns=[]
  59         columns.append(Column('feature_id', Integer,
  60                               ForeignKey('xfeatures.feature_id',
  61                                          ondelete='CASCADE'),
  62                               primary_key=True))
  63         columns.append(Column('key', Integer, primary_key=True,
  64                               autoincrement=False))
  65         columns.append(Column('value', String(256), primary_key=True))
  66         self.xfeaturevals = Table('xfeaturevals', metadata, *columns, mysql_engine='InnoDB')
  67
  68         metadata.create_all(self.engine)
  69
  70 #     def xfeature_inherit(self, path):
  71 #         """Return the (path, feature) inherited by the path, or None."""
  72 #
  73 #         s = select([self.xfeatures.c.path, self.xfeatures.c.feature_id])
  74 #         s = s.where(self.xfeatures.c.path <= path)
  75 #         #s = s.where(self.xfeatures.c.path.like(self.escape_like(path) + '%', escape='\\')) # XXX: Implement reverse and escape like...
  76 #         s = s.order_by(desc(self.xfeatures.c.path))
  77 #         r = self.conn.execute(s)
  78 #         l = r.fetchall()
  79 #         r.close()
  80 #         return l
  81
  82     def xfeature_get(self, path):
  83         """Return feature for path."""
  84
  85         s = select([self.xfeatures.c.feature_id])
  86         s = s.where(self.xfeatures.c.path == path)
  87         s = s.order_by(self.xfeatures.c.path)
  88         r = self.conn.execute(s)
  89         row = r.fetchone()
  90         r.close()
  91         if row:
  92             return row[0]
  93         return None
  94
  95     def xfeature_create(self, path):
  96         """Create and return a feature for path.
  97            If the path has a feature, return it.
  98         """
  99
 100         feature = self.xfeature_get(path)
 101         if feature is not None:
 102             return feature
 103         s = self.xfeatures.insert()
 104         r = self.conn.execute(s, path=path)
 105         inserted_primary_key = r.inserted_primary_key[0]
 106         r.close()
 107         return inserted_primary_key
 108
 109     def xfeature_destroy(self, path):
 110         """Destroy a feature and all its key, value pairs."""
 111
 112         s = self.xfeatures.delete().where(self.xfeatures.c.path == path)
 113         r = self.conn.execute(s)
 114         r.close()
 115
 116     def feature_dict(self, feature):
 117         """Return a dict mapping keys to list of values for feature."""
 118
 119         s = select([self.xfeaturevals.c.key, self.xfeaturevals.c.value])
 120         s = s.where(self.xfeaturevals.c.feature_id == feature)
 121         r = self.conn.execute(s)
 122         d = defaultdict(list)
 123         for key, value in r.fetchall():
 124             d[key].append(value)
 125         r.close()
 126         return d
 127
 128     def feature_set(self, feature, key, value):
 129         """Associate a key, value pair with a feature."""
 130
 131         s = self.xfeaturevals.select()
 132         s = s.where(self.xfeaturevals.c.feature_id == feature)
 133         s = s.where(self.xfeaturevals.c.key == key)
 134         s = s.where(self.xfeaturevals.c.value == value)
 135         r = self.conn.execute(s)
 136         xfeaturevals = r.fetchall()
 137         r.close()
 138         if len(xfeaturevals) == 0:
 139             s = self.xfeaturevals.insert()
 140             r = self.conn.execute(s, feature_id=feature, key=key, value=value)
 141             r.close()
 142
 143     def feature_setmany(self, feature, key, values):
 144         """Associate the given key, and values with a feature."""
 145
 146         #TODO: more efficient way to do it
 147         for v in values:
 148             self.feature_set(feature, key, v)
 149
 150     def feature_unset(self, feature, key, value):
 151         """Disassociate a key, value pair from a feature."""
 152
 153         s = self.xfeaturevals.delete()
 154         s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
 155                      self.xfeaturevals.c.key == key,
 156                      self.xfeaturevals.c.value == value))
 157         r = self.conn.execute(s)
 158         r.close()
 159
 160     def feature_unsetmany(self, feature, key, values):
 161         """Disassociate the key for the values given, from a feature."""
 162
 163         for v in values:
 164             conditional = and_(self.xfeaturevals.c.feature_id == feature,
 165                                self.xfeaturevals.c.key == key,
 166                                self.xfeaturevals.c.value == v)
 167             s = self.xfeaturevals.delete().where(conditional)
 168             r = self.conn.execute(s)
 169             r.close()
 170
 171     def feature_get(self, feature, key):
 172         """Return the list of values for a key of a feature."""
 173
 174         s = select([self.xfeaturevals.c.value])
 175         s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
 176                      self.xfeaturevals.c.key == key))
 177         r = self.conn.execute(s)
 178         l = [row[0] for row in r.fetchall()]
 179         r.close()
 180         return l
 181
 182     def feature_clear(self, feature, key):
 183         """Delete all key, value pairs for a key of a feature."""
 184
 185         s = self.xfeaturevals.delete()
 186         s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
 187                      self.xfeaturevals.c.key == key))
 188         r = self.conn.execute(s)
 189         r.close()