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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
40 from dbworker import DBWorker
43 class XFeatures(DBWorker):
44 """XFeatures are path properties that allow non-nested
45 inheritance patterns. Currently used for storing permissions.
48 def __init__(self, **params):
49 DBWorker.__init__(self, **params)
52 columns.append(Column('feature_id', Integer, primary_key=True))
53 columns.append(Column('path', String(2048)))
54 self.xfeatures = Table('xfeatures', metadata, *columns)
55 # place an index on path
56 Index('idx_features_path', self.xfeatures.c.path)
59 columns.append(Column('feature_id', Integer,
60 ForeignKey('xfeatures.feature_id',
63 columns.append(Column('key', Integer, primary_key=True))
64 columns.append(Column('value', String(255), primary_key=True))
65 self.xfeaturevals = Table('xfeaturevals', metadata, *columns)
67 metadata.create_all(self.engine)
68 metadata.bind = self.engine
70 def xfeature_inherit(self, path):
71 """Return the (path, feature) inherited by the path, or None."""
73 s = select([self.xfeatures.c.path, self.xfeatures.c.feature_id])
74 s = s.where(self.xfeatures.c.path <= path)
75 s = s.order_by(desc(self.xfeatures.c.path)).limit(1)
76 r = self.conn.execute(s)
79 if row and path.startswith(row[0]):
84 def xfeature_list(self, path):
85 """Return the list of the (prefix, feature) pairs matching path.
86 A prefix matches path if either the prefix includes the path,
87 or the path includes the prefix.
90 inherited = self.xfeature_inherit(path)
94 s = select([self.xfeatures.c.path, self.xfeatures.c.feature_id])
95 s = s.where(and_(self.xfeatures.c.path.like(path + '%'),
96 self.xfeatures.c.path != path))
97 s = s.order_by(self.xfeatures.c.path)
98 r = self.conn.execute(s)
103 def xfeature_create(self, path):
104 """Create and return a feature for path.
105 If the path already inherits a feature or
106 bestows to paths already inheriting a feature,
107 create no feature and return None.
108 If the path has a feature, return it.
111 prefixes = self.xfeature_list(path)
113 if (pl > 1) or (pl == 1 and prefixes[0][0] != path):
115 if pl == 1 and prefixes[0][0] == path:
116 return prefixes[0][1]
117 s = self.xfeatures.insert()
118 r = self.conn.execute(s, path=path)
119 inserted_primary_key = r.inserted_primary_key[0]
121 return inserted_primary_key
123 def xfeature_destroy(self, path):
124 """Destroy a feature and all its key, value pairs."""
126 s = self.xfeatures.delete().where(self.xfeatures.c.path == path)
127 r = self.conn.execute(s)
130 def feature_dict(self, feature):
131 """Return a dict mapping keys to list of values for feature."""
133 s = select([self.xfeaturevals.c.key, self.xfeaturevals.c.value])
134 s = s.where(self.xfeaturevals.c.feature_id == feature)
135 r = self.conn.execute(s)
136 d = defaultdict(list)
137 for key, value in r.fetchall():
142 def feature_set(self, feature, key, value):
143 """Associate a key, value pair with a feature."""
145 s = self.xfeaturevals.insert()
146 r = self.conn.execute(s, feature_id=feature, key=key, value=value)
149 def feature_setmany(self, feature, key, values):
150 """Associate the given key, and values with a feature."""
152 s = self.xfeaturevals.insert()
153 values = [{'feature_id':feature, 'key':key, 'value':v} for v in values]
154 r = self.conn.execute(s, values)
157 def feature_unset(self, feature, key, value):
158 """Disassociate a key, value pair from a feature."""
160 s = self.xfeaturevals.delete()
161 s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
162 self.xfeaturevals.c.key == key,
163 self.xfeaturevals.c.value == value))
164 r = self.conn.execute(s)
167 def feature_unsetmany(self, feature, key, values):
168 """Disassociate the key for the values given, from a feature."""
171 conditional = and_(self.xfeaturevals.c.feature_id == feature,
172 self.xfeaturevals.c.key == key,
173 self.xfeaturevals.c.value == v)
174 s = self.xfeaturevals.delete().where(conditional)
175 r = self.conn.execute(s)
178 def feature_get(self, feature, key):
179 """Return the list of values for a key of a feature."""
181 s = select([self.xfeaturevals.c.value])
182 s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
183 self.xfeaturevals.c.key == key))
184 r = self.conn.execute(s)
185 l = [row[0] for row in r.fetchall()]
189 def feature_clear(self, feature, key):
190 """Delete all key, value pairs for a key of a feature."""
192 s = self.xfeaturevals.delete()
193 s = s.where(and_(self.xfeaturevals.c.feature_id == feature,
194 self.xfeaturevals.c.key == key))
195 r = self.conn.execute(s)