Changing Ghost permalinks without breaking everything

26 Jan 2014

I’m a big fan of the Ghost blogging platform. Having heard Hannah Wolfe talk about it a couple of times, I was keen to try it out. In fact I purposefully held off setting up a blog for Node-RED until Ghost was available.

It was painless to set up and get running on my Web Faction hosted server - even though at that point Web Faction hadn’t created their one-click installer for it.

Ghost released their second stable version a couple weeks ago, which added, amongst many other new features, the ability for a post’s url to contain its date. This was a feature I hadn’t realised I was missing until I wrote a post on the blog called ‘Community News’. The intent was this would be a commonly used blog title as we post things we find people doing with Node-RED. However, without a date in the post, the urls would end up being .../community-news-1, .../community-new-2 .. etc. Perfectly functional, but not to my taste.

So I clicked to enable dated permalinks on the blog, and promptly found I had broken all of the existing post urls. I had half-hoped that on enabling the option, any already-published posts would not be affected - but that wasn’t the case; they all changed.

To fix this, I needed a way to redirect anyone going to one of the old urls to the corresponding new one. I don’t have access to the proxy running in front of my web host, so that wasn’t an option.

Instead, I added a bit of code to my installation of Ghost that deals with it.

In the top level directory of Ghost is a file called index.js. This is what gets invoked to run the platform and is itself a very simple file:

var ghost = require('./core');

ghost();

What this doesn’t reveal is that the call to ghost() accepts an argument of an instance of express, the web application framework that Ghost uses. This allows you to pass in an instance of Express that you’ve tweaked for your own needs - such as one that knows about the old urls and what they should redirect to:

var ghost = require('./core');
var express = require("express");

var app = express();

ghost(app);

var redirects = express();

var urlMap = [
   {from:'/version-0-2-0-released/', to:'/2013/10/16/version-0-2-0-released/'},
   {from:'/internet-of-things-messaging-hangout/', to:'/2013/10/21/internet-of-things-messaging-hangout/'},
   {from:'/version-0-3-0-released/', to:'/2013/10/31/version-0-3-0-released/'},
   {from:'/version-0-4-0-released/', to:'/2013/11/14/version-0-4-0-released/'},
   {from:'/version-0-5-0-released/', to:'/2013/12/21/version-0-5-0-released/'},
   {from:'/community-news-14012014/', to:'/2014/01/22/community-news/'}
];

for (var i=0; i<urlMap.length; i+=1) {
   var to = urlMap[i].to;
   redirects.all(urlMap[i].from,function(req,res) {
      res.redirect(301,to);
   });
}

app.use(redirects);

It’s all a bit hard-coded and I don’t know how compatible this will be with future releases of Ghost, but at least it keeps the old urls alive. After all, cool uris don’t change.

knolleary

Changing Ghost permalinks without breaking everything