VIM colors downloader in Python

Question

Recently, I wanted to change my vim colors to something new. So I went to the vim colors website and then I decided that I wanted to download ALL the colors.

So I wrote this simple Python script that will download all the files from: Vim Colors

I'm still learning Python and it would be amazing to get some feedback / suggestions if possible.

import os
import json
import requests
from bs4 import BeautifulSoup


class Spider:
    def __init__(self, total_pages=40):
        self.base_url = "http://vimcolors.com/?page="
        self.total_pages = total_pages
        self.download_dir = 'colors/'
        # If we don't have the download directory
        if not os.path.isdir(self.download_dir):
            print(self.download_dir, 'does not exist, trying to create it...')
            # create it...
            os.mkdir(self.download_dir)

    def download(self, name, url):
        # If we have already downloaded this file, just skip
        if os.path.isfile(self.download_dir + name):
            print('File:', name, 'already exists; skipping.')
            return

        try:
            # Get the response
            response = requests.get(url)
            # If response is 404 (Not Found), just exit
            if response.status_code == 404:
                raise Exception('File not found')
            # Create the file
            with open(self.download_dir + name, 'wb') as file_path:
                # Write content to the file
                file_path.write(response.content)
                # Confirm the download
                print('Downloaded', name)
        except:
            # This is a very generic error, perhaps I'll change it sometime :)
            print('Could not download the file', name)
            pass

    def crawl(self):
        def repo_formatter(scheme):
            return scheme['github_repo']['address'].replace('github.com', 'raw.githubusercontent.com') \
                   + '/master/colors/' + scheme['name'] + '.vim'

        # Loop over all the pages
        for page in range(self.total_pages):
            page_source = requests.get(self.base_url + str(page + 1))
            plain_text = page_source.text
            soup = BeautifulSoup(plain_text, 'lxml')

            # Get the data
            json_data = json.loads(soup.find('div', {'id': 'data'}).attrs['data-colorschemes'])

            # Download the files
            for data in json_data['colorschemes']:
                self.download(data['name'] + '.vim', repo_formatter(data))


colors_spider = Spider()
colors_spider.crawl()

Answer 1

Very nice code in general! Here are a few points, though:

Think about using os.makedirs instead of os.mkdir. The former allows creating nested directories (so os.makedirs("~/long/new/path") will create all other folders in betweetn as well, if needed).

You should never have a bare except. This prevents you to e.g. CTRL-C to abort the program, since it will also be caught. Use at least except Exception, which all normal exceptions inherit from (but not some special exceptions like pressing CTRL-C).

In general it is usually not the best idea to have a lot of string addition. You could use format instead in repo_formatter:

def repo_formatter(scheme):
    base_url = scheme['github_repo']['address'].replace('github.com', 'raw.githubusercontent.com')
    return '{}/master/colors/{}.vim'.format(base_url, scheme['name'])

You have some very obvious comments in your code, especially in download. Comments should explain why you do something and not what. The latter should be obvious from your code! And in that function it is really easy to follow what happens, because you have chosen appropriate variable names :)

Answer 2

Nice script! A few points on top of what @Graipher already pointed out.

Passing url parameters to requests

This is a hacky way to pass query parameters:

url = "http://vimcolors.com/?page="
# ...
page_source = requests.get(url + str(page + 1))

The proper way to do this is to pass the parameters in a dictionary:

url = "http://vimcolors.com"
# ...
page_source = requests.get(url, {'page': page + 1})

Building path strings

This is a hacky, non-portable way to build and work with path strings:

download_dir = 'colors/'
# ...

if os.path.isfile(download_dir + name):
    # ...

The proper way to do this is using os.path.join:

download_dir = 'colors'
# ...

if os.path.isfile(os.path.join(download_dir, name)):
    # ...

Don't repeat yourself

You wrote self.download_dir + name multiple times within the same scope. Don't repeat yourself, put it into a variable and reuse it.

Exception handling

There are several problems with this block of code:

try:
    # Get the response
    response = requests.get(url)
    # If response is 404 (Not Found), just exit
    if response.status_code == 404:
        raise Exception('File not found')
    # Create the file
    with open(self.download_dir + name, 'wb') as file_path:
        # Write content to the file
        file_path.write(response.content)
        # Confirm the download
        print('Downloaded', name)
except:
    # This is a very generic error, perhaps I'll change it sometime :)
    print('Could not download the file', name)
    pass

@Graipher already mentioned to not use generic exceptions. The coding style guide has many things to say about exceptions, I suggest to read it well.

The message you print in except may be misleading. As the try block includes not only the downloading, but also the writing to the file, if the latter raises an exception, it will be caught, and the message printed will be misleading, which can be extremely frustrating when trying to debug the problem. At the minimum, the try block should be split.

Finally, as this block of code is at the end of the function, the pass is pointless.