This is the fourth in a series of live lessons on using WordPress and Thesis as a Content Management System (CMS). In this case study we are creating a community library website. In this lesson we will be deciding what the custom taxonomies will be and if they are hierarchical or non-hierarchical. We are also looking at other data elements that we are capturing and using as custom post meta rather than as custom taxonomies.
So we follow a decision making tree. We discuss if an element should actually be a custom taxonomy or if it should be custom post meta. Next we look at decision factors for determining if the custom taxonomy should be hierarchical or not. Finally we apply this decision making system to the real world data elements we have.
Rick: Now the next part is to talk about our decision making about this taxonomy or our taxonomy decisions. So this is… what is this? This is Part 4 I think, of the series here. And we have you know, we’ve just discussed the different types of taxonomies and other kinds of organizational elements that we might use on this. Now we’re going to talk about how we make that decision because we have ISBN no., publication date, barcode call, media, circulation time, location, audience, topic, author, title and summary are going to be the title of the post and the content of the post. So those aren’t going to be organizational elements but everything else is in one way or the other.
So we come here and we say you know, in this decision making process, we have to decide whether something is a taxonomy or not and whether it’s hierarchical or non-hierarchical. And so the first step then is we ask ourselves, so what is the purpose of taxonomies? And the purpose of taxonomies is to group like objects in various ways to allow human browsing. And then you know in fact, what I’m going to do is do this as a presentation. Ah, forget it. Okay, group like objects in various ways to allow human browsing. You know, you don’t need a taxonomy or you don’t need organizational structures for searching, right? Because you could type in a search term, whatever search term you want and the computer will run out and look for that search term and return results with that search term in it. And so if you wanted to list books or if you wanted to find books that are in the you know, for children, you could easily have a database entry that says you know, who the audience is. So it could be you know, children or young children or something like that. You could easily search the database and come up with all of the entries that have audience equal young children. And so you don’t necessarily need a taxonomy to find it that way. The purpose for the taxonomy is so that you can go to website and click on a button that says books for children and then it will list all of the books for children. It’ll allow you to browse through it. And that’s the only reason why we have these taxonomies is because we want a mechanism for using our eyes and our you know, cognitive abilities to choose which record we want to look at. And so that is the purpose of the taxonomy. It’s to group like objects in various ways to allow human browsing.
Okay so the first question is, is the information unique per entry? And so if it’s a unique identifier, it should not be a taxonomy because there is no reason to have a group of 1. So for example, ISBN numbers you know, I believe, I’m fairly certain that ISBN numbers are unique. That is, they’re different for every single book and no two books have the same ISBN number. The ISBN number is intended to be a unique identifier for a book so this should not be a taxonomy. This should be post meta instead because we can still search for this but you’re never going to group by it because it’s unique. Okay so if it’s a unique identifier then it doesn’t want to be a taxonomy.
The next thing is, do you want to use it as a means of listing posts? So for example, where to go? Are you going to use barcode as a means of listing posts? And maybe barcode is also a unique identifier so it gets excluded from that. But how about publication date?You know, publication date is an important piece of data to capture and maybe an important piece of data to display but is it a way that you want to…are you going to want to show listing of all books published in 1976 for somebody to browse through and find? The chances are, that’s a very specialized query. The chances are somebody is not going to start looking for a book based on its publication date because it’s not a meaningful piece of information for the person who’s looking. There’s probably much more meaningful information like author or title or subject than date. And so, you probably don’t want to display books grouped by date as a means of you know, scanning through the books. So that probably means then that date or publication date is not an appropriate number for that.
It can also be that call number is not. But media probably is especially media for a you know, if you have 3000 books and 50 DVDs and 25 books on tape you know, or audiobooks, well, using Book as a means of displaying records probably isn’t that useful but it certainly would be for DVDs or for audiobooks. So you know, media can be a good determiner or a good way of listing or displaying posts and could be a good choice.
Location may very well be one of those things as well where you want to see you know, a listing of all the books in the specific location. Although again, maybe not. It may be just because it is… it’s not to say that we can’t search for all the books in a specific location because you could easily search for all the books in storage and we can have a means of searching all of the records by post meta for administrative users…or actually, for any user without it being a normal taxonomy. And so, that’s one of the questions you ask yourself is, is this something that you want to group or a means of listing a post? And if it is, then it should be a taxonomy.
So you have… the first thing we’re doing is we are understanding the purpose of a taxonomy. The 2nd thing we’re doing is our first reason why something should not be a taxonomy is because it’s a unique identifier. The 2nd reason why it shouldn’t be a taxonomy is because you don’t really want to use it as a means of listing posts. But if you passed those 2 tests then you’re going to need to decide is it hierarchical or not hierarchical? And so the question is you know, does it make sense for there to be a parent-child relationship inside of those terms?
So one obvious no answer is author. You may very want to… well, want to list books by author so you want to list… well, I can’t think of a reason for listing every book by James Dobson but let’s see… you could list every book you know, by author’s name and the author may very well have a whole bunch of different books under that name. But you know, there’s definitely… you don’t really care if you know, James Dobson’s son also wrote books and so you wouldn’t have a James Dobson as a category and then as a sub category, James Dobson’s son and another sub category, James Dobson’s daughter… and then under the son, James Dobson’s grandson you know. You wouldn’t do that. There’s no reason for a hierarchical relationship in author. So you know that is not hierarchical.
Topics may be hierarchical. Genre may be hierarchical. Even audience might be hierarchical although since there’s so few numbers of potential audience divisions, it’s probably not hierarchical. But that’s the question. Does it make sense for there to be a parent-child relationship inside of the terms? So if your genre is non-fiction and so under non-fiction, you have reference books and you know, original manuscripts and commentaries and history and biography and you know, you have those different kinds of divisions. That does make sense for that to be hierarchical, right? Especially if you’ve got non-fiction, history, and then you could break history down further you know, sort of in this case, you know, pre-New Testament or pre-historical and you know, based on periods so you could assign certain periods you know, hierarchical element. So that’s definitely a way in which you know, subject might be hierarchical.
And then does it make sense to assign one or many taxonomy terms to a post? So if you’re only going to assign one taxonomy term to a post then it ought to be hierarchical. But if you really want to assign more than one, then it should be non-hierarchical. So let’s take the authors for example again. You know, most of these only have a single author but there are lots and lots of books where you know, there may be compilations of individual writings of individual authors. You’ve got an editor and a bunch of authors. Or you’ve got you know, joint authorship of books. You know, the chances are, you are going to have books or pieces of media that have different authors or more than 1 author. And so author is not a good choice for hierarchical either. Not only is it there’s no hierarchy to it but also, it has… you might use more than one term, that is, more than one author. And so that should be a non-hierarchical.
However you know, topic… now, topic may also be that way where you know, the book might have several topics associated with it and if it’s got several topics associated with it then topic probably isn’t hierarchical either. But if you have genre and you’ve got this you know, non-fiction, history, you know, church history or something like that, you know, where you’ve got those 3 different levels of the hierarchy, then you are only going to assign one of those you know, genres to a book. And in that case, that could be hierarchical. So that’s the next question. Does it make sense to assign one or many taxonomy terms to a post? If you’re only going to assign one then hierarchical is a good choice.
So another good choice, even though this might not sound like it’s hierarchical, another good choice is location because if you’re going to use location as a way of grouping books, then you know, the book is only going to be located in one spot. And so since it’s only going to be located in one spot, it’s only going to have one reference. And so that might very well make it hierarchical. Same thing is potentially true for circulation time. You know,if you’re going to group books or list books by their length of circulation then length of circulation could be hierarchical also.
And then finally, oh and that’s it I guess. That is the last one so now what we’re going to do is we are going to… the next thing we are going to do is bring Pam back on the line and we’re going to walk through these things and we’re going to assign them, decide where each of them should go. So Pam, I’m unmuting your microphone.
Pam: Good morning, Rick.
Rick: Good morning Pam. How are you doing?
Rick: I’m sorry about that mix up. You know, I thought to myself, ‘Oh gosh, nobody showed up.’ So anyway, I’m glad you stuck with it. So here we go, we’ve got our list of things that we’re going to capture. I noticed you didn’t put genre on this list.
Pam: No, I realized…isn’t it, in that list, I didn’t use that term. I’m still kind of grappling with how does that apply to our selection and…
Rick: And it might not.
Pam: And what is the meaning of that term because it doesn’t exactly fit how we group our books.
Pam: Location is probably the closest thing we have to genre because we group biographies and so on together.
Rick: Right. And you know, part of the limitation that you have when you do that in a physical library is that really you know, you’ve got physical limitations that don’t exist in a virtual listing like this. And so you may very well be able to you know, provide another you know, visual sorting method whether it’s genre or topic or something. There may be another way in which a person can browse pre-established, pre-determined terms and say, ‘Okay, I want to look at all of the pre-Nicaean history.’ Or you know, whatever. There could be a…
Pam: I think topic is probably closest to genre because somebody might say, “Show me all the church history of this period.” Or all the books on marriage or all the books on parenting… so that’s the closest probably that we have to genre.
Rick: Okay. And I would guess that in that situation, topic is probably not hierarchical because you know, you might actually have… you probably often have more than one thing you would define as the topic in a book.
Rick: Right? And so yeah, it could very well be the case that there’s more than one.