Split out HTTP request manipulation functions from template_helpers.py, which
is in danger of becoming a "misc" or "util" module unnecessarily.
#!/usr/bin/python2.5
#
# Copyright 2008 the Melange authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Helpers for manipulating HTTP requests.
"""
__authors__ = [
'"Todd Larsen" <tlarsen@google.com>',
]
def getSingleIndexedParamValue(request, param_name, values=()):
"""Returns a value indexed by a query parameter in the HTTP request.
Args:
request: the Django HTTP request object
param_name: name of the query parameter in the HTTP request
values: list (or tuple) of ordered values; one of which is
retrieved by the index value of the param_name argument in
the HTTP request
Returns:
None if the query parameter was not present, was not an integer, or
was an integer that is not a valid [0..len(values)-1] index into
the values list.
Otherwise, returns values[int(param_name value)]
"""
value_idx = request.GET.get(param_name)
if isinstance(value_idx, (tuple, list)):
# keep only the first argument if multiple are present
value_idx = value_idx[0]
try:
# GET parameter 'param_name' should be an integer value index
value_idx = int(value_idx)
except:
# ignore bogus or missing parameter values, so return None (no message)
return None
if value_idx < 0:
# value index out of range, so return None (no value)
return None
if value_idx >= len(values):
# value index out of range, so return None (no value)
return None
# return value associated with valid value index
return values[value_idx]
def getSingleIndexedParamValueIfMissing(value, request, param_name,
values=()):
"""Returns missing value indexed by a query parameter in the HTTP request.
Args:
value: an existing value, or a "False" value such as None
request, param_name, values: see getSingleIndexParamValue()
Returns:
value, if value is "non-False"
Otherwise, returns getSingleIndexedParamValue() result.
"""
if value:
# value already present, so return it
return value
return getSingleIndexedParamValue(request, param_name, values=values)
# TODO(tlarsen): write getMultipleIndexParamValues() that returns a
# list of values if present, omitting those values that are
# out of range