[wp-hackers] Getting lowest/last-level terms in hierarchical taxonomy

[Harry Metcalfe]

You could maybe make a new table that stores details about leaf terms, and update it when terms are modified?

I helped out on a project where performance was also key, where we did the above, and it worked well. To be honest, I don't think WordPress's taxonomies will ever be very good if you need something highly performant - since parent/child relationships are only defined upwards (which is your problem here) and any nontrivial reading or manipulation either requires loads of joins or manipulation of large arrays. Or both.

Harry

Sent from my mobile

<div>-------- Original message --------</div><div>From: Nikola Nikolov <nikolov.tmw at gmail.com> </div><div>Date:2014/05/26  09:33  (GMT+00:00) </div><div>To: wp-hackers at lists.automattic.com </div><div>Subject: Re: [wp-hackers] Getting lowest/last-level terms in hierarchical
 	taxonomy </div><div>
</div>Yeah, that's one my thoughts, but I'm afraid it will cause too many queries
perhaps? Although from looking at the code it seems like
get_term_children() is calling _get_term_hierarchy() every time, which on
the other hand is storing it's data in an option in the options table...
I guess that might work :)

Alternatively, I can store the last-level terms(once I fetch them) in an
option as well and flush that option when a term is added/updated/deleted
from that taxonomy.

Any other ideas?


On Mon, May 26, 2014 at 6:19 AM, Haluk Karamete <halukkaramete at gmail.com>wrote:

> HI Nikola
> what if you walk thru all terms in that tax and check if the current term
> has children or not.
>
> http://codex.wordpress.org/Function_Reference/get_term_children
>
> Did I understand you correctly?
> Here's an interesting one - how can I get all of the *last-level* terms in
> a hierarchical taxonomy?
>
> Take the following hierarchy for instance:
>
>  - Food
>  - - Vegetables
>  - - - Cucumber
>  - - - Carrot
>  - - Bread
>  - - Fruits
>  - - - Citrus Fruits
>  - - - - Orange
>  - - - - Pomelo
>  - Potato
>
> ( I know the potato doesn't make sense, but I just wanted to illustrate the
> fact that some terms might be without children )
>
> In this case, I'd want to grab the following terms: Cucumber, Carrot,
> Bread, Orange, Pomelo, Potato.
>
> I've been looking around I haven't found an easy solution so far.
>
> I can think of two options - getting all terms and then recreating the tree
> from them, or getting each level of terms and doing subsequent get_terms()
> calls(which I don't like, since it's probably going to be very
> inefficient).
>
> My goal is to be able to present to the user a list of all last-level terms
> in the taxonomy and then behind the scenes assign the post to all terms
> from that tree(so, if you select Carrot, your post would be added to
> Vegetables and Food).
> I need to do that, since I have a custom table that stores post to post
> relations and I need to be able to query for all items in a specific
> category/list of categories with as little extra requests as possible(lots
> of data is expected to be stored and performance is key).
>
> Thanks,
> Nikola
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