'''
Manage command to export reference data for use by others.
Generates a CSV and JSON file for each Derrida Work in the database
(currently only Of Grammatology), with details for each reference
documented in the database.
Takes an optional argument to specify the output directory. Otherwise,
files are created in the current directory.
'''
import codecs
from collections import OrderedDict
import csv
import json
import os.path
from django.core.management.base import BaseCommand
from derrida.books.models import DerridaWork
[docs]class Command(BaseCommand):
'''Export reference data for each Derrida Work as CSV and JSON'''
help = __doc__
#: fields for CSV output
csv_fields = [
'id', 'page', 'page location', 'type', 'book title', 'book id',
'book page', 'book type', 'anchor text', 'interventions'
]
[docs] def add_arguments(self, parser):
parser.add_argument(
'-d', '--directory',
help='Specify the directory where files should be generated')
[docs] def handle(self, *args, **kwargs):
for derrida_work in DerridaWork.objects.all():
base_filename = '%s_references' % derrida_work.slug
if kwargs['directory']:
base_filename = os.path.join(kwargs['directory'], base_filename)
# generate filenames based on slug ?
# Can we use the same data to generate both CSV and JSON?
# aggregate reference data to be exported for use in generating
# CSV and JSON output
refdata = [self.reference_data(ref)
for ref in derrida_work.reference_set.all()]
# list of dictionaries can be output as is for JSON export
with open('{}.json'.format(base_filename), 'w') as jsonfile:
json.dump(refdata, jsonfile, indent=2)
# generate CSV export
with open('{}.csv'.format(base_filename), 'w') as csvfile:
# write utf-8 byte order mark at the beginning of the file
csvfile.write(codecs.BOM_UTF8.decode())
csvwriter = csv.DictWriter(csvfile, fieldnames=self.csv_fields)
csvwriter.writeheader()
for reference in refdata:
csvwriter.writerow(self.flatten_dict(reference))
[docs] def reference_data(self, reference):
'''Generate a dictionary of data to export for a single
:class:`~derrida.books.models.Reference` object'''
return OrderedDict([
('id', reference.get_uri()),
('page', reference.derridawork_page),
('page location', reference.derridawork_pageloc),
('book', OrderedDict([
('id', reference.instance.get_uri()),
('title', reference.instance.display_title()),
('page', reference.book_page),
('type', reference.book.item_type),
])),
('type', str(reference.reference_type)),
('anchor text', reference.anchor_text),
# use intervention URI as identifier
('interventions', [
intervention.get_uri()
for intervention in reference.interventions.all()
])
])
[docs] def flatten_dict(self, data):
'''Flatten a dictionary with nested dictionaries or lists into a
key value pairs that can be output as CSV. Nested dictionaries will be
flattened and keys combined; lists will be converted into semi-colon
delimited strings.'''
flat_data = {}
for key, val in data.items():
# for a nested subdictionary, combine key and nested key
if isinstance(val, dict):
for subkey, subval in val.items():
flat_data[' '.join([key, subkey])] = subval
# convert list to a delimited string
elif isinstance(val, list):
flat_data[key] = ';'.join(val)
else:
flat_data[key] = val
return flat_data
