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bfe_meta.py
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bfe_meta.py
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# -*- coding: utf-8 -*-
##
## This file is part of Invenio.
## Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2013 CERN.
##
## Invenio is free software; you can redistribute it and/or
## modify it under the terms of the GNU General Public License as
## published by the Free Software Foundation; either version 2 of the
## License, or (at your option) any later version.
##
## Invenio 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
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Invenio; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
"""BibFormat element - meta"""
__revision__ = "$Id$"
import cgi
from invenio.bibformat_elements.bfe_server_info import format_element as server_info
from invenio.bibformat_elements.bfe_client_info import format_element as client_info
from invenio.htmlutils import create_tag
from invenio.bibindex_engine import get_field_tags
from invenio.config import CFG_WEBSEARCH_ENABLE_GOOGLESCHOLAR, CFG_WEBSEARCH_ENABLE_OPENGRAPH
def format_element(bfo, name, tag_name='', tag='', kb='', kb_default_output='', var='', protocol='googlescholar'):
"""Prints a custom field in a way suitable to be used in HTML META
tags. In particular conforms to Google Scholar harvesting protocol as
defined http://scholar.google.com/intl/en/scholar/inclusion.html and
Open Graph http://ogp.me/
@param tag_name: the name, from tag table, of the field to be exported
looks initially for names prefixed by "meta-"<tag_name>
then looks for exact name, then falls through to "tag"
@param tag: the MARC tag to be exported (only if not defined by tag_name)
@param name: name to be displayed in the meta headers, labelling this value.
@param kb: a knowledge base through which to process the retrieved value if necessary.
@param kb: when a '<code>kb</code>' is specified and no match for value is found, what shall we
return? Either return the given parameter or specify "{value}" to return the retrieved
value before processing though kb.
@param var: the name of a variable to output instead of field from metadata.
Allowed values are those supported by bfe_server_info and
bfe_client_info. Overrides <code>name</code> and <code>tag_name</code>
@param protocol: the protocol this tag is aimed at. Can be used to switch on/off support for a given "protocol". Can take values among 'googlescholar', 'opengraph'
@see: bfe_server_info.py, bfe_client_info.py
"""
if protocol == 'googlescholar' and not CFG_WEBSEARCH_ENABLE_GOOGLESCHOLAR:
return ""
elif protocol == 'opengraph' and not CFG_WEBSEARCH_ENABLE_OPENGRAPH:
return ""
tags = []
if var:
# delegate to bfe_server_info or bfe_client_info:
value = server_info(bfo, var)
if value.startswith("Unknown variable: "):
# Oops variable was not defined there
value = client_info(bfo, var)
return not value.startswith("Unknown variable: ") and \
create_metatag(name=name, content=cgi.escape(value, True)) \
or ""
elif tag_name:
# First check for special meta named tags
tags = get_field_tags("meta-" + tag_name)
if not tags:
# then check for regular tags
tags = get_field_tags(tag_name)
if not tags and tag:
# fall back to explicit marc tag
tags = [tag]
if not tags:
return ''
out = []
values = [bfo.fields(marctag, escape=9) for marctag in tags]
for value in values:
if isinstance(value, list):
for val in value:
if isinstance(val, dict):
out.extend(val.values())
else:
out.append(val)
elif isinstance(value, dict):
out.extend(value.values())
else:
out.append(value)
out = dict(zip(out, len(out)*[''])).keys() # Remove duplicates
if name == 'citation_date':
for idx in range(len(out)):
out[idx] = out[idx].replace('-', '/')
if kb:
if kb_default_output == "{value}":
out = [bfo.kb(kb, value, value) for value in out]
else:
out = [bfo.kb(kb, value, kb_default_output) for value in out]
return '\n'.join([create_metatag(name=name, content=value) for value in out])
def create_metatag(name, content):
"""
Wraps create_tag
"""
if name.startswith("og:"):
return create_tag('meta', property=name, content=content)
else:
return create_tag('meta', name=name, content=content)
def escape_values(bfo):
"""
Called by BibFormat in order to check if output of this element
should be escaped.
"""
return 0

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