server_more_pythonic.py

# http://slides.com/robinchew/deck

from collections import defaultdict
from textwrap import dedent
from urllib.parse import urlparse, parse_qs

from wsgiref.util import setup_testing_defaults
from wsgiref.simple_server import make_server

import csv
import os
import sys

PORT = int(sys.argv[1])

CSV_PATH = 'students.csv'
FIELDS = ('Name', 'Degree',)

def index(data):
    if set(data.keys()) == set(FIELDS):
        csv_exists = os.path.isfile(CSV_PATH)

        with open(CSV_PATH, 'a') as f:
            if not csv_exists:
                f = open(CSV_PATH, 'w')
                f.write(','.join(FIELDS)+'\n')

            f.write(','.join(data[field] for field in FIELDS)+'\n')

    return '''
        <h1>Index</h1>
        <pre>{0}</pre>
        <form method="POST">
            {1}
            <input type="submit" />
        </form>
    '''.format(
        str(data),
        ''.join(
            '{0} <input name="{0}" />'.format(name)
            for name in FIELDS
        )
    )

def stat(data):
    degree_field = FIELDS[1]

    count_map = defaultdict(int)
    with open(CSV_PATH) as f:
        for row in csv.DictReader(f):
            count_map[row[degree_field]] += 1

    return '''
        <h1>Stat</h1>
        <h2>{0}</h2>
        <style>
            table{{
                border-collapse: collapse;
            }}
            td{{
                border: 1px solid grey;
            }}
        </style>
        <table>
            <tr>
                {1}
            </tr>
        </table>
    '''.format(
        FIELDS[1],
        '</tr><tr>'.join(
            '<td>{0}</td><td>{1}</td>'.format(value, count)
            for value, count in count_map.items()
        )
    )

router = {
    '': index,
    'stat': stat,
}

def app(environ, start_response):
    #setup_testing_defaults(environ)
    path = environ['PATH_INFO']
    method = environ['REQUEST_METHOD']

    status = '200 OK'
    headers = [('Content-type', 'text/html')]

    start_response(status, headers)

    if method == 'POST':
        query_string = environ['wsgi.input'].read(int(environ['CONTENT_LENGTH'])).decode('ascii')
    else:
        query_string = environ['QUERY_STRING']

    data = {
        k: l[0] if len(l) else None
        for k, l in parse_qs(query_string).items()
    }
    return [router.get(
        path.strip('/'),
        lambda d: ''
    )(data).encode('ascii')]

httpd = make_server('', PORT, app)

print("serving at port", PORT)
httpd.serve_forever()