app/soc/views/helper/requests.py
changeset 269 0f1acc4c3e1e
parent 267 0c008a43443b
child 365 74dec172944e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/views/helper/requests.py	Fri Oct 03 22:17:05 2008 +0000
@@ -0,0 +1,179 @@
+#!/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>',
+  ]
+
+import urlparse
+
+
+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
+
+
+def isReferrerSelf(request,
+                   expected_prefix=None, suffix=None):
+  """Returns True if HTTP referrer path starts with the HTTP request path.
+    
+  Args:
+    request: the Django HTTP request object; request.path is used if
+      expected_path is not supplied (the most common usage)
+    expected_prefix: optional HTTP path to use instead of the one in
+      request.path; default is None (use request.path)
+    suffix: suffix to remove from the HTTP request path before comparing
+      it to the HTTP referrer path in the HTTP request object headers
+      (this is often an link name, for example, that may be changing from
+      a POST referrer to a GET redirect target) 
+  
+  Returns:
+    True if HTTP referrer path begins with the HTTP request path (either
+      request.path or expected_prefix instead if it was supplied), after
+      any suffix was removed from that request path
+    False otherwise
+       
+  """
+  http_from = request.META.get('HTTP_REFERER')
+      
+  if not http_from:
+    # no HTTP referrer, so cannot possibly start with expected prefix
+    return False
+
+  from_path = urlparse.urlparse(http_from).path
+  
+  if not expected_prefix:
+    # use HTTP request path, since expected_prefix was not supplied
+    expected_prefix = request.path
+
+  if suffix:
+    # remove suffix (such as a link name) before comparison
+    chars_to_remove = len(suffix)
+    
+    if not suffix.startswith('/'):
+      chars_to_remove = chars_to_remove + 1
+
+    expected_prefix = expected_prefix[:-chars_to_remove]
+
+  if not from_path.startswith(expected_prefix):
+    # expected prefix did not match first part of HTTP referrer path
+    return False
+ 
+  # HTTP referrer started with (possibly truncated) expected prefix
+  return True
+
+
+def replaceSuffix(path, old_suffix, new_suffix=None, params=None):
+  """Replace the last part of a URL path with something else.
+
+  Also appends an optional list of query parameters.  Used for
+  replacing, for example, one link name at the end of a relative
+  URL path with another.
+
+  Args:
+    path: HTTP request relative URL path (with no query arguments)
+    old_suffix: expected suffix at the end of request.path component;
+      if any False value (such as None), the empty string '' is used
+    new_suffix: if non-False, appended to request.path along with a
+      '/' separator (after removing old_suffix if necessary)
+    params: an optional dictionary of query parameters to append to
+      the redirect target; appended as ?<key1>=<value1>&<key2>=...
+      
+  Returns:
+    /path/with/new_suffix?a=1&b=2
+  """    
+  if not old_suffix:
+    old_suffix = ''
+
+  old_suffix = '/' + old_suffix
+
+  if path.endswith(old_suffix):
+    # also removes any trailing '/' if old_suffix was empty
+    path = path[:-len(old_suffix)]
+
+  if new_suffix:
+    # if present, appends new_suffix, after '/' separator
+    path = '%s/%s' % (path, new_suffix)
+
+  if params:
+    # appends any query parameters, after a '?' and separated by '&'
+    path = '%s?%s' % (path, '&'.join(
+        ['%s=%s' % (p,v) for p,v in params.iteritems()]))
+
+  return path