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# Wraps DB-API 2.0 query results to provide a nice list and dictionary interface.
# Copyright (C) 2002 Dr. Conan C. Albrecht <conan_albrecht@byu.edu>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
# I created this class and related functions because I like accessing
# database results by field name rather than field number. Accessing
# by field number has many problems: code is less readable, code gets
# broken when field positions change or fields are added or deleted from
# the query, etc.
#
# This class should have little overhead if you are already using fetchall().
# It wraps each result row in a ResultRow class which allows you to
# retrieve results via a dictionary interface (by column name). The regular
# list interface (by column number) is also provided.
#
# I can't believe the DB-API 2.0 api didn't include dictionary-style results.
# I'd love to see the reasoning behind not requiring them of database connection
# classes.
# This module comes from:
# http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/163605
def get_rows(cursor, sql):
"""Return a list of ResultRow objects from an SQL query."""
# run the query
cursor.execute(sql)
# return the list
return getdict(cursor.fetchall(), cursor.description)
def getdict(results, description):
"""Return the list of DBRows in `results` with a given description."""
# get the field names
fields = {}
for i in range(len(description)):
fields[description[i][0]] = i
# generate the list of DBRow objects
rows = []
for result in results:
rows.append(DBRow(result, fields))
# return to the user
return rows
class DBRow(object):
"""A single row in a result set.
Each DBRow has a dictionary-style and list-style interface.
"""
def __init__(self, row, fields):
"""Called by ResultSet function. Don't call directly"""
self.fields = fields
self.row = row
self._extra_fields = {}
def __repr__(self):
return "<DBrow with %s fields>" % len(self)
def __str__(self):
"""Return a string representation"""
return str(self.row)
def __getattr__(self, attr):
return self.row[self.fields[attr]]
def set_extra_attr(self, attr, value):
self._extra_fields[attr] = value
def __getitem__(self, key):
"""Return the value of the named column"""
if type(key) == type(1): # if a number
return self.row[key]
else: # a field name
return self.row[self.fields[key]]
def __setitem__(self, key, value):
"""Not used in this implementation"""
raise TypeError, "can't set an item of a result set"
def __getslice__(self, i, j):
"""Return the value of the numbered column"""
return self.row[i: j]
def __setslice__(self, i, j, list):
"""Not used in this implementation"""
raise TypeError, "can't set an item of a result set"
def keys(self):
"""Return the field names"""
return self.fields.keys()
def keymappings(self):
"""Return a dictionary of the keys and their indices in the row"""
return self.fields
def has_key(self, key):
"""Return whether the given key is valid"""
return self.fields.has_key(key)
def as_dict(self):
d = {}
for field_name, pos in self.fields.iteritems():
d[field_name] = self.row[pos]
for field_name, field in self._extra_fields.iteritems():
d[field_name] = field
return d
def __len__(self):
"""Return how many columns are in this row"""
return len(self.row)
def __nonzero__(self):
return len(self.row) != 0
def __eq__(self, other):
## Error if other is not set
if other == None:
return False
return self.fields == other.fields
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