识别RSS源是否已更新的最佳方法

Question

I am trying to build a simple RSS feed reader in RoR as my first project. When trying to find the best way to do so, I keep reading about using conditional get to only get the feed if it has been modified since the last update.

Assuming that the feed that I am getting has this information in the header, how do I only accomplish this?

Sun, 19 Nov 2017 05:21:56 +0800

Currently, I do something similar to the following:

xml = HTTParty.get(url).body feed = Feedjira.parse(xml)

** I am pretty new so any other suggestion or material that might help will be appritiated.

Answer 1

to see if the RSS is updated you should maintain and check the headers like Etag and Last-Modified

So once you read the RSS feed first time extract these headers and maintain on reader side. And for subsequent request just do comparison for these tags, and if changed do parse the feed.

response = HTTParty.get(url)
headers = response.headers
last_modified = headers['Last-Modified']
etag = headers['Etag']
body = response.body
feed = Feedjira.parse(body) if(stored_last_modified != last_modified or etag != stored_etag)

might be old but good to read this