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marc_reader.py
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Mon, Oct 14, 15:40

marc_reader.py
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# -*- coding: utf-8 -*-
#
# This file is part of Invenio.
# Copyright (C) 2013, 2014 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.
"""
Marc reader.
This reader (or any) shouldn't be used directly, at least in the normal use
cases. Instead :class:`~invenio.modules.jsonalchemy.readers.Reader` should be
used with the explicit format.
"""
import copy
import re
from six import iteritems
from werkzeug.utils import import_string
from invenio.base.globals import cfg
from invenio.base.utils import try_to_eval
from invenio.modules.jsonalchemy.reader import Reader
from invenio.modules.jsonalchemy.errors import ReaderException
from invenio.modules.jsonalchemy.registry import functions
class MarcReader(Reader):
"""Marc reader."""
__master_format__ = 'marc'
split_marc = re.compile('<record.*?>.*?</record>', re.DOTALL)
@staticmethod
def split_blob(blob, schema=None, **kwargs):
"""Split the blob using <record.*?>.*?</record> as pattern.
Note 1: Taken from invenio.legacy.bibrecord:create_records
Note 2: Use the DOTALL flag to include newlines.
"""
if schema in (None, 'xml'):
for match in MarcReader.split_marc.finditer(blob):
yield match.group()
else:
raise StopIteration()
def guess_model_from_input(self):
"""Guess from the input Marc the model to be used in this record.
This is the simplest implementation possible, it just take all `980__a`
tags and sets it as list of models.
The guess function could be easily change by setting
`CFG_MARC_MODEL_GUESSER` with an importable string
"""
guess_function = cfg.get('CFG_MARC_MODEL_GUESSER', None)
if guess_function:
return import_string(guess_function)(self)
try:
return [coll['a'].lower()
for coll in self.rec_tree.get('980__') if 'a' in coll]
except TypeError:
try:
return self.rec_tree.get('980__', {})['a']
except:
return '__default__'
def _get_elements_from_blob(self, regex_key):
"""Retrieve elements from the blob or the intermediate structure.
:return: A tuple containing the first match for the list of regex_keys
"""
if regex_key in ('entire_record', '*'):
return self.rec_tree
for k in regex_key:
regex = re.compile(k)
keys = filter(regex.match, self.rec_tree.keys())
for key in keys:
if key in self.rec_tree:
return (key, self.rec_tree.get(key, []))
return ('', [])
def _prepare_blob(self, *args, **kwargs):
"""Transform the incoming blob into recstruct.
FIXME: stop using recstruct!
"""
from invenio.legacy.bibrecord import create_record
class SaveDict(dict):
__getitem__ = dict.get
def dict_extend_helper(d, key, value):
"""Helper function.
If the key is present inside the dictionary it creates a list (if
not present) and extends it with the new value.
Almost as in `list.extend`
"""
if key in d:
current_value = d.get(key)
if not isinstance(current_value, list):
current_value = [current_value]
current_value.append(value)
value = current_value
d[key] = value
self.rec_tree = SaveDict()
record, status_code, errors = create_record(self._blob)
if status_code == 0:
if isinstance(errors, list):
errors = "\n".join(errors)
# There was an error
raise ReaderException(
"There was an error while parsing MARCXML: %s" % (errors,))
for key, values in iteritems(record):
if key < '010' and key.isdigit():
self.rec_tree[key] = [value[3] for value in values]
else:
for value in values:
field = SaveDict()
for subfield in value[0]:
dict_extend_helper(field, subfield[0], subfield[1])
dict_extend_helper(
self.rec_tree,
(key + value[1] + value[2]).replace(' ', '_'), field)
def _apply_rules(self, json_id, field_name, rule):
"""Override default behavior.
See :meth:`~invenio.modules.jsonalchemy.readers.Reader._apply_rules`.
Tries to apply all the rules defined for marc and as soon as it can
apply one it stops the process.
It also keeps the marc_tag that comes from
:meth:`._get_elements_from_blob`
:param json_id: as in
:meth:`~invenio.modules.jsonalchemy.readers.Reader._apply_rules`
:param field_name: as in
:meth:`~invenio.modules.jsonalchemy.readers.Reader._apply_rules`
:param rule: as in
:meth:`~invenio.modules.jsonalchemy.readers.Reader._apply_rules`
"""
for field_def in rule['rules'].get(
self._json.additional_info.master_format, []):
if not self._evaluate_before_decorators(field_def):
continue
marc_tag, elements = self._get_elements_from_blob(
field_def['source_tags'])
if not isinstance(elements, (list, tuple)):
elements = (elements, )
for element in elements:
tmp_field_def = copy.deepcopy(field_def)
tmp_field_def['source_tags'] = [marc_tag, ]
if not self._evaluate_on_decorators(tmp_field_def, element):
continue
try:
value = try_to_eval(
tmp_field_def['function'],
functions(self._json.additional_info.namespace),
value=element, self=self._json)
self._remove_none_values(value)
info = self._find_field_metadata(json_id, field_name,
'creator', tmp_field_def)
self._json['__meta_metadata__'][field_name] = info
self._json.__setitem__(field_name, value, extend=True,
exclude=['decorators',
'extensions'])
except Exception as e:
self._json.errors.append(
"Rule Error - Unable to apply rule for field "
"'%s' with value '%s'. \n%s"
% (field_name, element, str(e)),)
if field_name in self._json._dict_bson:
break
reader = MarcReader

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