Create a url with an article's title

问题:

I have articles in MongoDB. I want the URLs for the articles to be readable. If I have an article named "How to Use Flask and MongoDB Seamlessly with Heroku", I want the URL to be something like localhost:5000/blog/how-to-use-flask-and-mongodb-seamlessly-with-heroku.

What is the best way to accomplish this? Any pointers in the right direction are appreciated. I wasn't sure exactly where to start on this one.

回答1:

You are looking for a way to generate a "slug" and use that to identify the post.

If you want to use just a slug, all post titles will have to have a unique slug (which approximately means a unique title). This also means that if you change the post's title, the url could change, which would invalidate bookmarks and other outside links.

A better method is to do something like what Stack Overflow does for questions. If you look at this question's URL, you'll notice it has a unique id and a slug. In fact, the slug is optional, you can still get to this page by removing it from the url.

You'll need a way to generate slugs, and a custom url converter. The inflection library provides a nice way to slugify strings with the parameterize method. The following url converter takes an object and returns a url with the_object.id and the_object.title as a slug. When parsing a url, it will just return the object's id, since the slug is optional.

from inflection import parameterize
from werkzeug.routing import BaseConverter

class IDSlugConverter(BaseConverter):
    """Matches an int id and optional slug, separated by "/".

    :param attr: name of field to slugify, or None for default of str(instance)
    :param length: max length of slug when building url
    """

    regex = r'-?\d+(?:/[\w\-]*)?'

    def __init__(self, map, attr='title', length=80):
        self.attr = attr
        self.length = int(length)
        super(IDSlugConverter, self).__init__(map)

    def to_python(self, value):
        id, slug = (value.split('/') + [None])[:2]
        return int(id)

    def to_url(self, value):
        raw = str(value) if self.attr is None else getattr(value, self.attr, '')
        slug = parameterize(raw)[:self.length].rstrip('-')
        return '{}/{}'.format(value.id, slug).rstrip('/')

Register the converter so it can be used in routes:

app.url_map.converters['id_slug'] = IDSlugConverter

Use it in a route:

@app.route('/blog/<id_slug:id>')
def blog_post(id):
    # get post by id, do stuff

Generate a url for a post. Note that you pass the object ('post'), not just the id, to the id parameter.:

url_for('blog_post', id=post)
# /blog/1234/the-post-title

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_{Converter written by me for the Stack Overflow Python chat room site.}