Viewing file: 
reflector.py (5.81 KB) -rw-r--r--Select action/file-type:
(
+) |
(
+) |
(
+) |
Code (
+) |
Session (
+) |
(
+) |
SDB (
+) |
(
+) |
(
+) |
(
+) |
(
+) |
(
+) |
# -*- test-case-name: twisted.test.test_reflector -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
import weakref, warnings
from twisted.enterprise.util import DBError
class Reflector:
"""
DEPRECATED.
Base class for enterprise reflectors. This implements row caching.
"""
populated = 0
def __init__(self, rowClasses):
"""
Initialize me against a database.
@param rowClasses: a list of row class objects that describe the
database schema.
"""
warnings.warn("twisted.enterprise.reflector is deprecated since "
"Twisted 8.0", category=DeprecationWarning, stacklevel=2)
# does not hold references to cached rows.
self.rowCache = weakref.WeakValueDictionary()
self.rowClasses = rowClasses
self.schema = {}
self._populate()
def __getstate__(self):
d = self.__dict__.copy()
del d['rowCache']
return d
def __setstate__(self, state):
self.__dict__ = state
self.rowCache = weakref.WeakValueDictionary()
self._populate()
def _populate(self):
"""Implement me to populate schema information for the reflector.
"""
raise DBError("not implemented")
def populateSchemaFor(self, tableInfo):
"""This is called once for each registered rowClass to add it
and its foreign key relationships for that rowClass to the
schema."""
self.schema[ tableInfo.rowTableName ] = tableInfo
# add the foreign key to the foreign table.
for foreignTableName, childColumns, parentColumns, containerMethod, autoLoad in tableInfo.rowForeignKeys:
self.schema[foreignTableName].addForeignKey(childColumns,
parentColumns, tableInfo.rowClass,
containerMethod, autoLoad)
def getTableInfo(self, rowObject):
"""Get a TableInfo record about a particular instance.
This record contains various information about the instance's
class as registered with this reflector.
@param rowObject: a L{RowObject} instance of a class previously
registered with me.
@raises twisted.enterprise.row.DBError: raised if this class was not
previously registered.
"""
try:
return self.schema[rowObject.rowTableName]
except KeyError:
raise DBError("class %s was not registered with %s" % (
rowObject.__class__, self))
def buildWhereClause(self, relationship, row):
"""util method used by reflectors. builds a where clause to link a row to another table.
"""
whereClause = []
for i in range(0,len(relationship.childColumns)):
value = getattr(row, relationship.parentColumns[i][0])
whereClause.append( [relationship.childColumns[i][0], EQUAL, value] )
return whereClause
def addToParent(self, parentRow, rows, tableName):
"""util method used by reflectors. adds these rows to the parent row object.
If a rowClass does not have a containerMethod, then a list attribute "childRows"
will be used.
"""
parentInfo = self.getTableInfo(parentRow)
relationship = parentInfo.getRelationshipFor(tableName)
if not relationship:
raise DBError("no relationship from %s to %s" % ( parentRow.rowTableName, tableName) )
if not relationship.containerMethod:
if hasattr(parentRow, "childRows"):
for row in rows:
if row not in parentRow.childRows:
parentRow.childRows.append(row)
else:
parentRow.childRows = rows
return
if not hasattr(parentRow, relationship.containerMethod):
raise DBError("parent row (%s) doesnt have container method <%s>!" % (parentRow, relationship.containerMethod))
meth = getattr(parentRow, relationship.containerMethod)
for row in rows:
meth(row)
####### Row Cache ########
def addToCache(self, rowObject):
"""NOTE: Should this be recursive?! requires better container knowledge..."""
self.rowCache[ rowObject.getKeyTuple() ] = rowObject
def findInCache(self, rowClass, kw):
keys = []
keys.append(rowClass.rowTableName)
for keyName, keyType in rowClass.rowKeyColumns:
keys.append( kw[keyName] )
keyTuple = tuple(keys)
return self.rowCache.get(keyTuple)
def removeFromCache(self, rowObject):
"""NOTE: should this be recursive!??"""
key = rowObject.getKeyTuple()
if self.rowCache.has_key(key):
del self.rowCache[key]
####### Row Operations ########
def loadObjectsFrom(self, tableName, parent=None, data=None,
whereClause=[], loadChildren=1):
"""Implement me to load objects from the database.
@param whereClause: a list of tuples of (columnName, conditional, value)
so it can be parsed by all types of reflectors. eg.::
whereClause = [("name", EQUALS, "fred"), ("age", GREATERTHAN, 18)]
"""
raise DBError("not implemented")
def updateRow(self, rowObject):
"""update this rowObject to the database.
"""
raise DBError("not implemented")
def insertRow(self, rowObject):
"""insert a new row for this object instance.
"""
raise DBError("not implemented")
def deleteRow(self, rowObject):
"""delete the row for this object from the database.
"""
raise DBError("not implemented")
# conditionals
EQUAL = 0
LESSTHAN = 1
GREATERTHAN = 2
LIKE = 3
__all__ = ['Reflector', 'EQUAL', 'LESSTHAN', 'GREATERTHAN', 'LIKE']
