source: main/waeup.kofa/trunk/src/waeup/kofa/utils/helpers.txt @ 7974

:mod:`waeup.kofa.utils.helpers` -- Helpers for Kofa
***************************************************

.. module:: waeup.kofa.utils.helpers

Helper functions for Kofa.

.. :doctest:

:func:`remove_file_or_directory`
================================

.. function:: remove_file_or_directory(path)

   Removes a file or directory given by a path. We can remove files:

     >>> import os
     >>> import tempfile
     >>> old_location = os.getcwd()
     >>> new_location = tempfile.mkdtemp()
     >>> os.chdir(new_location)

     >>> from waeup.kofa.utils.helpers import remove_file_or_directory
     >>> open('blah', 'wb').write('nonsense')
     >>> 'blah' in os.listdir('.')
     True

     >>> remove_file_or_directory('blah')
     >>> 'blah' in os.listdir('.')
     False

   We can remove directories:

     >>> os.mkdir('blah')
     >>> 'blah' in os.listdir('.')
     True

     >>> remove_file_or_directory('blah')
     >>> 'blah' in os.listdir('.')
     False


:func:`copy_filesystem_tree`
============================

.. function:: ccopy_filesystem_tree(src_path, dst_path[, overwrite=False[, del_old=False]])

   Copies the contents of an (existing) directory to another
   (existing) directory.

   :param src_path: filesystem path to copy from
   :type  src_path: string
   :param dst_path: filesystem path to copy to
   :type  dst_path: string
   :keyword overwrite: Whether exiting files with same names should be
                     overwritten.
   :type  overwrite: bool
   :keyword del_old: Whether old contents in destination path should be 
                   removed.
   :type  del_old: bool
   :return: List of non-copied files
 
   Both directories must exist.

   Unix hidden files and directories (starting with '.') are not
   processed by this function.

   Without any further parameters, we can copy complete file trees:

     >>> os.mkdir('src')
     >>> os.mkdir('dst')
     >>> open(os.path.join('src', 'blah'), 'wb').write('nonsense')

     >>> from waeup.kofa.utils.helpers import copy_filesystem_tree
     >>> result = copy_filesystem_tree('src', 'dst')

   As a result we get a list of non-copied files:

     >>> result
     []

   The created file was indeed copied:

     >>> 'blah' in os.listdir('dst')
     True

   Hidden files (i.e. such starting with a dot) are not copied:

     >>> open(os.path.join('src', '.blah'), 'wb').write('nonsense')
     >>> result = copy_filesystem_tree('src', 'dst')
     >>> '.blah' in os.listdir('dst')
     False

   This function supports some keyword parameters as explained below.

Using ``overwrite``
-------------------

Boolean. If set to ``True``, any existing and same named files and
directories in the destination dir are overwritten with copies from
the source. Default is `False`.

Normally, existing same named files in the destination are not
overwritten:

    >>> open(os.path.join('src', 'blah'), 'wb').write('newnonsense')
    >>> result = copy_filesystem_tree('src', 'dst')
    >>> open(os.path.join('dst', 'blah'), 'rb').read()
    'nonsense'

Instead the filename is added to the result (a list of non-copied
files):

    >>> result
    ['blah']

If, however, we use `overwrite`, the existing file will be
overwritten:

    >>> result = copy_filesystem_tree('src', 'dst', overwrite=True)
    >>> open(os.path.join('dst', 'blah'), 'rb').read()
    'newnonsense'

    >>> result
    []

This also works for complete directories:

    >>> os.mkdir(os.path.join('src', 'mydir'))
    >>> os.mkdir(os.path.join('dst', 'mydir'))
    >>> open(os.path.join(
    ...   'src', 'mydir', 'blah'), 'wb').write('srcblah')
    >>> open(os.path.join(
    ...   'dst', 'mydir', 'blah'), 'wb').write('dstblah')

    >>> result = copy_filesystem_tree('src', 'dst', overwrite=True)
    >>> open(os.path.join('dst', 'mydir', 'blah'), 'rb').read()
    'srcblah'


Using ``del_old``
-----------------

Boolean. If set to ``True``, any copied files and directories will be
removed from the src dir. Default is `False`.

    >>> result = copy_filesystem_tree('src', 'dst', overwrite=True,
    ...                                           del_old=True)
    >>> os.listdir('src')
    ['.blah']

All files and directories are removed from src, except the hidden file
we created in the beginning.


Clean up:

    >>> import shutil
    >>> shutil.rmtree(new_location)
    >>> os.chdir(old_location)
    


:func:`get_inner_HTML_part()`
=============================

.. function:: get_inner_HTML_part(html_code)

   Get the 'inner' part out of a piece of HTML code.

   Helper function mainly to extract 'real content' from already
   rendered forms.

   The term 'inner part' here means the ``<form>`` part of an HTML
   snippet. If this cannot be found, we look for a ``<body>`` part and
   if this cannot be found as well, we simply return the whole input.

   If a ``<form>`` part can be found in an HTML snippet, this is
   returned with all preceeding/following stuff stripped:

     >>> from waeup.kofa.utils.helpers import get_inner_HTML_part
     >>> print get_inner_HTML_part("""<html>
     ... <head>
     ... </head>
     ... <BLANKLINE>
     ... <body>
     ... <form action="http://localhost/myuniversity/faculties/TF/add"
     ...       method="post" class="edit-form"
     ...       enctype="multipart/form-data">
     ...   <h1>Add a department</h1>
     ... </form>
     ... </body>
     ... </html>
     ... """)
     <BLANKLINE>
     <form action="http://localhost/myuniversity/faculties/TF/add"
           method="post" class="edit-form"
           enctype="multipart/form-data">
     <BLANKLINE>
       <h1>Add a department</h1>
     </form>
     <BLANKLINE>
     <BLANKLINE>

   If there is no ``<form>`` part, try to find any ``<body>`` part:

     >>> print get_inner_HTML_part("""<html>
     ... <head>
     ... </head>
     ... <BLANKLINE>
     ... <body>
     ...  <div>Some content</div>
     ... </body>
     ... </html>
     ... """)
     <BLANKLINE>
      <div>Some content</div>
     <BLANKLINE>

   If there is also no ``<body>`` tag, we return the input as-is:

     >>> print get_inner_HTML_part("""<div>
     ...  <div>Some content</div>
     ... </div>
     ... """)
     <div>
      <div>Some content</div>
     </div>