Moving to PowerPress - customising GUID?

[iainfogg]

We have previously used a hand-crafted XML file for our podcast - this is accessed by users through a Feedburner feed we have set up.

We are now about to start using PowerPress as we move to a Wordpress site, but I have a dilemma which I could really do with some help with.

When we go live, the plan is to change where the Feedburner feed reads from, so existing subscribers will not need to re-subscribe to a new feed. The feed will be more or less the same as the other, but as it's generated differently, there will inevitably be parameters which vary between the old and new feeds.

Here's the problem which I am currently stuck on - how can I stop existing subscribers getting each episode again in iTunes?

From what I can tell, iTunes uses the 'guid' parameter in the feed to identify whether an episode is a new one or a duplicate. The handcrafted XML that we currently use has the URL of the MP3 file as the guid - however, PowerPress sets guid to be a link to the page containing the MP3 file.

The effect this has is that if I change Feedburner to point to the new XML file, then update the podcast in iTunes, it will double up every single episode in the podcast list as it thinks they are all new episodes.

Any ideas how I can transition from handcrafted XML to PowerPress without every existing subscriber getting double episodes in iTunes?

For example, can the guid parameter be customised? Or is there anything else you can suggest?

Here's a link to an abbreviated version of the handcrafted XML file:

http://79.170.44.113/audaciouscitychurch.com/Podcast/handmade.xml

Here's a link to the PowerPress equivalent:

http://79.170.44.113/audaciouscitychurch.com/feed/podcast/

Thanks!

[angelo]

The guid <guid> tag in the RSS2 feed is a WordPress created tag. PowerPress does not add or modify this value. WordPress uses the actual posts URL as the guid value. This is typically the standard for this as the guid needs to be unique, and there's nothing more unique that a specific URL.

I am not familiar with FeedBurner and the options it provides, but you may be able to setup FeedBurner to display say 20 items of your feed, then in your WordPRess blog go to the feed settings and only display 1 item at first, and create 1 new podcast episode. If FeedBurner is smart enough, it should only add the new post and keep the remaining 19 that use the previous guid's. Not sure if that work but I'd look into that as an option. You just have to remember to increase the number of posts per feed to 2 when you add a second episode, etc...

The other is to just make the change at the same time you put out a new episode. iTunes only downlaods the latest episode, users will have to manually download previous episodes anyway. I would venture to guess that most folks will not notice the last X episodes re-appearing as new.

[iainfogg]

I can't find anything in Feedburner to limit the number of entries in the feed.

Your second option would work fine for existing users, but would mean that new subscribers would not be able to download the old options.

I had been trying to find where the guid tag came from, thanks for the explanation.

This is a long shot, but is there any way to merge an XML file into the podcast feed, at the end of it? That way, I could simply add new episodes to the new feed, but could somehow splice in the contents of the old XML file with the old guids. That way, old subscribers and new would be able to get new and existing podcasts. Does that seem at all possible?

Thanks for your help

[iainfogg]

Or can you think of a way to write a secondary PHP page that would dynamically load in the PowerPress feed, then would manually add in the old episodes by reading them from an XML file stored locally? Then I could just point Feedburner to that page, and it would have the new stuff formatted properly, and the old stuff as per the old file, so no duplicates.

Unfortunately I am a PHP novice, so don't really know where to start, and so far haven't found anything from my time googling which would do something close to that.

[angelo]

I'm not sure, but this sounds more like a job for Yahoo Pipes. http://pipes.yahoo.com/pipes/

[iainfogg]

Thanks - I've spent a while on Yahoo Pipes since you suggested it. At first glance it looked like the answer, as it's a breeze to merge the old and new XML files into one. The problem is that you can't simply output the created XML.

If you ask Pipes to output it as RSS, it strips all the iTunes attributes out, and I can't find any other way to get the XML out.

Any other ideas?

Thanks!

[angelo]

Yahoo Pipes removes the podcast episodes? That sucks. Maybe the output Feed needs to be RSS2 specific in order to keep the attributes, I know the iTunes tags are for RSS 2.0 feeds only.

I can't think of any other ideas outside of developing something custom for the problem.

I would just make the switch right before you release a new episode. Even if you set the feed to display 20 items, iTunes is only going to download the latest episode. It will appear as if there are 19 other new episodes to the users, but most users will most likely not notice.

[iainfogg]

It doesn't remove the podcast episodes - just the iTunes: elements. I have no idea why you can't just take a merged XML output, but there seems to be no way. And when you ask for RSS, apparently the iTunes attributes aren't supported by Pipes (prob because it's not RSS2, as you say) so it pulls them all out. So frustrating - 90% there, merging the files, but just can't export it!

I am now working on an idea to edit the GUID manually in the database for the episodes which have already been released, but so far the editing GUID is not coming through - don't know if there's a cache, or some code I need to change.

I will let you know the outcome.

[iainfogg]

Ok - the solution to moving to Powerpress without messing up my existing iTunes feed for subscribers was to add all the posts by using a spreadsheet in Excel to produce a CSV file with all the post data (titles and descriptions extracted from the existing feed).

Then I used the "CSV Importer" plugin to add all the posts into Wordpress.

After that, I used phpMyAdmin and went through all the posts in the Wordpress database that I'd just added, and edited the GUID of each one to be identical to the GUID from the old feed.

Then I redirected Feedburner to look at the new Powerpress-produced file, rather than the old handcrafted XML file. I also had to ensure that Feedburner was presenting exactly the same title for the feed as before, to avoid iTunes appearing to create a second podcast.

By doing that, I was able to move from a hand-crafted XML file to using Powerpress without losing subscribers, without getting double entries for downloaded files, and without getting two podcasts showing in iTunes.

Got there in the end! Thanks for your help, angelo!