Title: loop failure or operator error?
Last modified: May 9, 2017
---
# loop failure or operator error?
* Resolved [mazoola](https://wordpress.org/support/users/mazoola/)
* (@mazoola)
* [9 years ago](https://wordpress.org/support/topic/loop-failure-or-operator-error/)
* **Airpress 1.1.35**
* Chester –
* I’ve run into an issue with looping using the [apr_loop] shortcode. (I think
I mentioned this in passing in an earlier post.) I’m not sure if it’s an Airpress
problem or if I’m trying to push recursive references too far….
* This is using the wardrobe Airtable base I mentioned earlier. Essentially, the
base is centered around the ‘garment’ table, each record of which describes an
individual item of clothing. In addition, one or more garments may be brought
together as an ‘outfit’, stored in a separate table. A garment may be a component
of multiple outfits. Garments and outfits both may have associated images.
* I encountered this problem while working on the garment display page of my application,
which is generated via a Virtual Post matching the garment table’s primary field(
in this case, the garment’s name, slugged, concatenated with “-” and the garment
record’s Auto Number).
* As part of the template to which the VP maps is a section detailing each outfit
of which that garment is a component. Contained within the outfit detail are
the outfit images and a section on each garment within the outfit, including
garment images. Accordingly, there are several [apr_loop]s in play.
* ```
garment
| |
| [apr_loop1] =-> image[0]...image[x]
|
[apr_loop2] =-> outfit[0]...outfit[x]
| |
| [apr_loop3] =-> image[0]...image[x]
|
[apr_loop4] =-> garment[0]...garment[x]
|
[apr_loop5] =-> image[0]...image[x]
```
* The problem occurs with [apr_loop2], above. Frankly, it took me a while to run
into this, as in my initial implementation of the database, a garment is never
a component of more than one outfit. In my original tests, everything worked
fine, down through [apr_loop5]. When I added a second outfit to a garment as
a test, though, rather than display information on each outfit, it apparently
merged outfit information. (That is, for the outfit name, my app reported the
names of all associated outfits, followed by a merged and deduped list of all
garments making up those outfits.)
* Further investigation revealed I was still running an unclosed [apr_loop2], as
discussed in [this earlier post](http://wordpress.org/support/topic/trouble-reproducing-virtual-post-example/).
This seemingly causes no problems when the garment is a component of only a single
outfit, but fails when a second outfit is added.
* When I add an [/apr_loop] shortcode to the template in order to close the loop,
the loop fails completely; in my httpd_error.log, I find this message:
* **“AH01071: Got error ‘PHP message: PHP Fatal error: Call to a member function
getFieldValues() on null in /[…]/wp-content/plugins/airpress/lib/chetmac/Airpress.
php on line 76.'”**
* In stepping through the code – and my apologies in advance, if I’ve bollixed
up something here, but my php is beyond rusty – it appears the problem occurs
as the app attempts to set up [apr_loop4]. Here’s a snippet of code from the
template (prettified a bit and minus some unimportant ‘div’s):
* ```
[apr_populate field="outfit|garment" relatedTo="garment"]
[apr_loop4 field="outfit|garment"]
{{name}}
[apr_loop5 field="images"]
[/apr_loop5]
[/apr_loop4]
```
* As best I can tell (after seeding numerous airpress_debug() statements throughout
the code), Airpress begins to process [apr_loop4] through ‘outfit|garment’ records.
It branches correctly into nested loop processing at line 69. After the ArrayShift()
in line 72, $field = ‘outfit’ and $keys = ‘Array[0] => garment’.
* Failing line 76 reads:
`$records_to_loop = $this->currentRecord[$field]->getFieldValues(
$keys);` Given the values for $field and $keys, this would suggest ‘$this->currentRecord’
should reference an AirpressRecord corresponding to an entry from the garment
table. However, if I dump ‘$this->currentRecord’ immediately before the failure,
it references an outfit entry. Since an outfit record contains no ‘outfit’ field,
an attempt to reference ‘$this->currentRecord[‘outfit’]’ would return null —
which [presumably] would cause the ‘Call to a member function […] on null’ fatal
error. (After further digging, I have to wonder if the problem somehow involves
an earlier invocation of that `$this->currentRecord = $previousRecord` swap in
line 159 — but that’s as far as I’ve been able to take it.)
* Now, I realize everything from “In stepping through the code” onward may be complete
rubbish; as I’ve said, it’s been years since I’ve done any php hacking — and
my involvement was minimal, even then. If that’s the case, feel free to ignore
that portion, with prejudice. As regards the rest, if I’m pushing the shortcode
through one too many levels of recursion, let me know, and I’ll try to find another
way to handle it. (For my own purposes, simply asserting a garment may be a component
of only one outfit would solve the problem; however, I’m interested in seeing
if I can create a pure Airtable implementation that might serve as a lifestyle
template for more generic use.)
* Again, thanks for releasing such a full-featured and, as I am increasingly discovering,
so elegantly coded a plugin, as well as for all your work to explain and support
it!
* Maz
Viewing 1 replies (of 1 total)
* Thread Starter [mazoola](https://wordpress.org/support/users/mazoola/)
* (@mazoola)
* [9 years ago](https://wordpress.org/support/topic/loop-failure-or-operator-error/#post-9145642)
* Chester –
* After a lot of working on this one (and more airpress_debug() statements than
I care to remember), I managed to come up with a construction that worked as
desired. (Note: I still needed the SORT_REGULAR _sorttype _on line 231 of AirpressCollection.
php, so if that introduces failures down the line, I guess this isn’t resolved.)
I am still interested in understanding better some of the rules of Airpress (
for instance, for the apr_loop3, below, I populate “outfit|garment” but loop
only on “garment” — why?), but for the moment, I can at least move on.
* Again, the situation is as follows: I’m displaying a ‘garment’ record via a VirtualPost.
One or more garments may be brought together into an outfit (a record in the ‘
outfits’ table), and a garment may be part of more than one outfit. As part of
the garment display, I want to show all outfits of which it is a part, displayed
as the outfit name, thumbnails of images of the outfit, and then all garments
that make up the outfit (including the current garment), as well as thumbnails
of all garment images.
* Here’s the structure that ultimately worked, minus field display shortcodes,
etc.:
* ```
garment
[apr_populate field="outfit" relatedTo="outfits"]
[apr_loop field="outfit"]
[apr_loop2 field="outfitImages"]
[/apr_loop2]
[apr_populate field="outfit|garment" relatedTo="garments"]
[apr_loop3 field="garment"]
[apr_loop4 field="images"]
[/apr_loop4]
[/apr_loop3]
[/apr_loop]
```
* Once it was done, I could understand better why it required the syntax it does.
Maybe with my next display, I’ll be better able to anticipate this.
Thanks,
Maz
Viewing 1 replies (of 1 total)
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* Last reply from: [mazoola](https://wordpress.org/support/users/mazoola/)
* Last activity: [9 years ago](https://wordpress.org/support/topic/loop-failure-or-operator-error/#post-9145642)
* Status: resolved