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band_list_scraper.py
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band_list_scraper.py
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import argparse, datetime, os, json, csv
import logging
logger = logging.getLogger(__name__)
import bs4
from baseScraper import BaseScraper
class BandListScraper(BaseScraper):
"""
Collects brief band info from https://www.metal-archives.com/browse/letter
"""
def __init__(self, outfile='', test=False):
"""
Params:
outfile - where to put CSV
test - do a shorter test instead of a full run
"""
super().__init__()
if not outfile:
date = datetime.datetime.utcnow()
date_str = date.strftime('%Y%m%d_%H%M%S')
outfile = 'metal-archives_band_list_' + date_str + '.csv'
self.outfile = str(outfile)
print('Will output band data to', self.outfile)
self.test = bool(test)
if self.test:
print('Doing a shorter test run instead of a full scrape')
# letters used in the browse tabs: A-Z, NBR, ~
self.letters = ['NBR', '~']
self.letters.extend(map(chr, range(ord('A'), ord('Z')+1)))
if self.test:
self.letters = ['A', 'B']
print('Using letters =', self.letters)
# seems their API requires getting 500 bands at a time
self.display_length = 500
def run(self):
"""
Do the stuff. Will close things at the end of .run()
"""
# check if the output file already exists and ask the user if they wish to overwrite
if os.path.isfile(self.outfile):
print('The outfile "{}" already exists.'.format(self.outfile))
response = input('Overwrite (y/n): ').lower()
if response != 'y':
print('Okay, bailing')
return
else:
print('Okay, will overwrite')
self.openOutfile()
total_records_sum = 0
for letter in self.letters:
print('Getting stuff for letter =', letter)
# Make the first request
# That will tell us the total number of entries for this letter
start = 0
data = self.makeRequest(letter, start=start)
self.writeBandData(data['aaData'])
total_records = data['iTotalRecords']
total_records_sum += total_records
print('There are {} records for letter "{}"'.format(total_records, letter))
n_do = max(0, total_records - self.display_length) // self.display_length + 1
if self.test:
n_do = min(2, n_do)
print('Going to do {} more requests'.format(n_do))
# Now make all the other requests
for _ in range(n_do):
start += self.display_length
data = self.makeRequest(letter, start=start)
self.writeBandData(data['aaData'])
self.close()
self.closeOutfile()
print('There should be {} rows in {}'.format(total_records_sum+1, self.outfile))
def close(self):
super().close()
def makeRequest(self, letter, start=0):
"""
Make a GET request and return the JSON response as a dict
"""
url = self.base_url + '/browse/ajax-letter/l/' + str(letter) + '/json/1'
if start % self.display_length != 0:
raise RuntimeError("Bug in the scraper. In experiments, it appears "
"iDisplayStart must be a multiple of {}".format(self.display_length))
payload = {'sEcho': '',
'iDisplayStart': start,
'iDisplayLength': self.display_length}
print('Making request for letter={} start={}'.format(letter, start))
response = self.sessionGet(url, params=payload)
try:
data = response.json()
except json.JSONDecodeError as e:
print('Looks like the response is not JSON...')
raise e
return data
def openOutfile(self):
self.outfile_handle = open(self.outfile, 'w')
fieldnames = ('band_url', 'band', 'country', 'genre', 'status')
self.outfile_writer = csv.DictWriter(self.outfile_handle, fieldnames)
self.outfile_writer.writeheader()
def writeBandData(self, band_data):
"""
Writes band data to the outfile.
Takes band data of the form
["<a href='https://www.metal-archives.com/bands/Abducted/3540381624'>Abducted</a>",
'Spain',
'Thrash Metal',
'<span class="split_up">Split-up</span>']
and cleans it up a bit. Specifically, this stores the URL (from href), name (from text),
country, genre, and status (from text).
This isn't the most performant implementation, but that's okay since
we're gonna be sleeping between requests so we're not blasting MA's
servers.
"""
for data_list in band_data:
soup = bs4.BeautifulSoup(data_list[0], 'html5lib')
soup2 = bs4.BeautifulSoup(data_list[3], 'html5lib')
name = soup.a.text
url = soup.a.get('href')
country = data_list[1]
genre = data_list[2]
status = soup2.span.text
self.outfile_writer.writerow({'band': name,
'band_url': url,
'country': country,
'genre': genre,
'status': status})
def closeOutfile(self):
self.outfile_handle.close()
if __name__ == '__main__':
parser = argparse.ArgumentParser(description='Scrape metal-archives.com for all bands.')
parser.add_argument('--outfile', type=str, default=None,
help='filename of output CSV file')
parser.add_argument('--test', action='store_true',
help='Do a shorter test run instead of a full scrape')
args = parser.parse_args()
scraper = BandListScraper(outfile=args.outfile,
test=args.test,
)
scraper.run()