Cheetah/Utils/WebInputMixin.py

   1 #!/usr/bin/env python
   2 # $Id: WebInputMixin.py,v 1.10 2006/01/06 21:56:54 tavis_rudd Exp $
   3 """Provides helpers for Template.webInput(), a method for importing web
   4 transaction variables in bulk.  See the docstring of webInput for full details.
   5
   6 Meta-Data
   7 ================================================================================
   8 Author: Mike Orr <iron@mso.oz.net>
   9 License: This software is released for unlimited distribution under the
  10          terms of the MIT license.  See the LICENSE file.
  11 Version: $Revision: 1.10 $
  12 Start Date: 2002/03/17
  13 Last Revision Date: $Date: 2006/01/06 21:56:54 $
  14 """
  15 __author__ = "Mike Orr <iron@mso.oz.net>"
  16 __revision__ = "$Revision: 1.10 $"[11:-2]
  17
  18 from Cheetah.Utils.Misc import useOrRaise
  19
  20 class NonNumericInputError(ValueError): pass
  21
  22 ##################################################
  23 ## PRIVATE FUNCTIONS AND CLASSES
  24
  25 class _Converter:
  26     """A container object for info about type converters.
  27     .name, string, name of this converter (for error messages).
  28     .func, function, factory function.
  29     .default, value to use or raise if the real value is missing.
  30     .error, value to use or raise if .func() raises an exception.
  31     """
  32     def __init__(self, name, func, default, error):
  33         self.name = name
  34         self.func = func
  35         self.default = default
  36         self.error = error
  37
  38
  39 def _lookup(name, func, multi, converters):
  40     """Look up a Webware field/cookie/value/session value.  Return
  41     '(realName, value)' where 'realName' is like 'name' but with any
  42     conversion suffix strips off.  Applies numeric conversion and
  43     single vs multi values according to the comments in the source.
  44     """
  45     # Step 1 -- split off the conversion suffix from 'name'; e.g. "height:int".
  46     # If there's no colon, the suffix is "".  'longName' is the name with the
  47     # suffix, 'shortName' is without.
  48     # XXX This implementation assumes "height:" means "height".
  49     colon = name.find(':')
  50     if colon != -1:
  51         longName = name
  52         shortName, ext = name[:colon], name[colon+1:]
  53     else:
  54         longName = shortName = name
  55         ext = ''
  56
  57     # Step 2 -- look up the values by calling 'func'.
  58     if longName != shortName:
  59         values = func(longName, None) or func(shortName, None)
  60     else:
  61         values = func(shortName, None)
  62     # 'values' is a list of strings, a string or None.
  63
  64     # Step 3 -- Coerce 'values' to a list of zero, one or more strings.
  65     if   values is None:
  66         values = []
  67     elif isinstance(values, str):
  68         values = [values]
  69
  70     # Step 4 -- Find a _Converter object or raise TypeError.
  71     try:
  72         converter = converters[ext]
  73     except KeyError:
  74         fmt = "'%s' is not a valid converter name in '%s'"
  75         tup = (ext, longName)
  76         raise TypeError(fmt % tup)
  77
  78     # Step 5 -- if there's a converter func, run it on each element.
  79     # If the converter raises an exception, use or raise 'converter.error'.
  80     if converter.func is not None:
  81         tmp = values[:]
  82         values = []
  83         for elm in tmp:
  84             try:
  85                 elm = converter.func(elm)
  86             except (TypeError, ValueError):
  87                 tup = converter.name, elm
  88                 errmsg = "%s '%s' contains invalid characters" % tup
  89                 elm = useOrRaise(converter.error, errmsg)
  90             values.append(elm)
  91     # 'values' is now a list of strings, ints or floats.
  92
  93     # Step 6 -- If we're supposed to return a multi value, return the list
  94     # as is.  If we're supposed to return a single value and the list is
  95     # empty, return or raise 'converter.default'.  Otherwise, return the
  96     # first element in the list and ignore any additional values.
  97     if   multi:
  98         return shortName, values
  99     if len(values) == 0:
 100         return shortName, useOrRaise(converter.default)
 101     return shortName, values[0]
 102
 103 # vim: sw=4 ts=4 expandtab