MLA_term_list pass value for child_of

Thanks for an interesting question. Thanks as well for including the full source text of your form and shortcodes and the link to your page; very helpful.

I have worked out a solution for your request. Here are a form and shortcodes that are working on my test system:

<form id="mla-text-form" action="." method="post" class="row">
<strong>UCCELLI</strong>
[mla_term_list taxonomy=attachment_category mla_output=dropdown parent=0 mla_control_name=main_category mla_item_parameter=current_main_category show_count=false use_filters=true]
<br>
[mla_term_list taxonomy=attachment_category mla_output=dropdown mla_option_value="{+slug+}" child_of="{+template:({+request:main_category+}|1)+}" mla_control_name=sub_category mla_item_parameter=current_sub_category show_count=true hierarchical=true depth=0 use_filters=true]
<br>
<input id="text-form-submit" name="text_form_submit" type="submit" value="Visualizza le immagini">
</form>
 
[mla_gallery]
attachment_category="{+template:({+request:sub_category+}|no-term-selected)+}" 
posts_per_page=25 mla_output="paginate_links,prev_next" orderby=date order=DESC
mla_link_href="{+new_url+}?mla_paginate_current={+new_page+}&main_category={+request:main_category+}&sub_category={+request:sub_category,url+}"
[/mla_gallery]
 
[mla_gallery attachment_category="{+template:({+request:sub_category+}|no-term-selected)+}" posts_per_page=25 orderby=date order=DESC mla_caption="{+title+} : {+description+}" mla_link_href="/richiedi-stampa/?current_id={+attachment_ID+}" mla_nolink_text="Seleziona una categoria per visualizzare le immagini corrispondenti."]

I have made a number of changes to your shortcodes so either copy the above text as-is or be very careful when you update your text.

I have added a second dropdown control at the top of the form, using the mla_control_name=main_category and mla_item_parameter=current_main_category parameters to give it unique names. This control uses the parent=0 parameter to select all the main categories, the top-level terms, in the taxonomy. If you have top-level terms that should be excluded from the list you can add parameters to achieve that. The show_count=false parameter disables adding the number of term assignments to this list.

I have modified the original shortcode to accept the value selected in the top control:

child_of="{+template:({+request:main_category+}|1)+}"

The template accepts the main category when it is present and substitutes 1 when it is not, so the control is not displayed until a main category is selected. I have added the mla_control_name=sub_category and mla_item_parameter=current_sub_category parameters to give unique names.

You will see a new parameter, use_filters=true, added to both [mla_term_list] shortcodes. This is used by the “MLA UI Elements Example” plugin I added to the application; it retains the values selected in the dropdown controls when the page is refreshed. You will find instructions for adding this plugin to your application below.

I have changed the data selection parameter in both of the [mla_gallery] shortcodes to attachment_category="{+template:({+request:sub_category+}|no-term-selected)+}", using the name from the second term list control. I have also changed the mla_link_href parameter to use the unique names of both term list controls:

mla_link_href="{+new_url+}?mla_paginate_current={+new_page+}&main_category={+request:main_category+}&sub_category={+request:sub_category,url+}"

During my testing I discovered two MLA defects that prevented the above example from working properly. I have fixed these defects and uploaded a new MLA Development Version dated 20211108 that contains the corrected code. You can find step-by-step instructions for using the Development Version in this earlier topic:

PHP Warning on media upload with Polylang

Once the Development Version is installed you must install and activate the example plugin. Navigate to the Settings/Media library Assistant Documentation tab and click the “Example Plugins” button. Type “elements” in the text box and click “Search Plugins” to filter the table.

You are looking for the “MLA UI Elements Example” plugin. Find that plugin and hover over the title in the left-most column. Click the “Install” rollover action, then go to the WordPress Plugins/Installed Plugins submenu and activate the example plugin as you would any other plugin.

Once the Development Version and new example plugin are installed and active you can use the source text I provided above to update your page. The updated code will be part of my next MLA version, but in the interim it would be great if you could install the Development Version and the example plugin and let me know if they work for you. I will leave the topic unresolved for now. Thanks for your patience while I developed this solution.

Thanks for your update with the positive feedback, your progress report and the new question. The updated page on your site looks great!

Adding a third control to show a three-level hierarchy might be possible as long as every “Specie” has at least one child term. A user will have to select a value in all three controls to display a gallery. It will not be possible to, for example, select PAESAGGIO and then only select “paesaggio montano” to see the “mountain landscape” images in all of the third-level categories. Does that make sense, and is that acceptable?

I am also unsure what will happen when the user changes the main Categoria control. I think the second level should be updated and displayed while the third level and the gallery should disappear. Does that make sense, and is that acceptable?

If the above solution and limits are acceptable I can investigate further. Thanks for any additional details you can provide.

Thanks for your post with the additional details on what you have in mind. Thanks as well for your patience in awaiting my response.

There is no easy way to “automatically navigate to a new dedicate page when the user selects the main category” but I have worked out an alternative that might work for you. I have added two more dropdown controls to the existing page. Now there is one main level control, two second level controls and one third level control. Depending on the main category selected only one of the two second level controls is displayed. If the “UCCELLI” category is selected, making a selection on the second level will cause the third level control to be displayed. For any other main category, selecting the second level will display the gallery.

For your site I found this option for the UCCELLI category:

<option class="term-list-term term-list-dropdown-term level-0" value="127">UCCELLI</option>

I have used the “127” value in the source text below. If that’s not right you can make an adjustment. The [mla_gallery] shortcodes have been updated to use either the second level or third level term, whichever is present. Here is the code working on my system:

<form id="mla-text-form" action="." method="post" class="row">
<strong>UCCELLI</strong>
[mla_term_list taxonomy=attachment_category mla_output=dropdown parent=0 mla_control_name=main_category mla_item_parameter=current_main_category show_count=false use_filters=true]
<br>
[mla_term_list taxonomy=attachment_category mla_output=dropdown include_tree=127 child_of="{+template:({+request:main_category+}|1)+}" mla_control_name=include_category mla_item_parameter=current_include_category show_count=true pad_counts=false hierarchical=true depth=1 use_filters=true]
<br>
[mla_term_list taxonomy=attachment_category mla_output=dropdown mla_option_value="{+slug+}" exclude_tree=127 child_of="{+template:({+request:main_category+}|1)+}" mla_control_name=sub_category mla_item_parameter=current_sub_category show_count=true pad_counts=false hierarchical=true depth=0 use_filters=true]
<br>
[mla_term_list taxonomy=attachment_category mla_output=dropdown mla_option_value="{+slug+}" include_tree=127 child_of="{+template:({+request:include_category+}|1)+}" mla_control_name=third_category mla_item_parameter=current_third_category show_count=true pad_counts=false hierarchical=true depth=0 use_filters=true]<br>
<input id="text-form-submit" name="text_form_submit" type="submit" value="Visualizza le immagini">
</form>
 
[mla_gallery]
attachment_category="{+template:({+request:sub_category+}|{+request:third_category+}|no-term-selected)+}" tax_include_children=false
posts_per_page=25 mla_output="paginate_links,prev_next" orderby=date order=DESC
mla_link_href="{+new_url+}?mla_paginate_current={+new_page+}&main_category={+request:main_category+}&sub_category={+request:sub_category,url+}"
[/mla_gallery]
 
[mla_gallery attachment_category="{+template:({+request:sub_category+}|{+request:third_category+}|no-term-selected)+}" tax_include_children=false posts_per_page=25 orderby=date order=DESC mla_caption="{+title+} : {+description+}" mla_link_href="/richiedi-stampa/?current_id={+attachment_ID+}" mla_nolink_text="Seleziona una categoria per visualizzare le immagini corrispondenti."]

The limitation of this approach is that it only works for one three-level tree.

To make this code work I had to make some minor changes to the MLA core code. I have uploaded a new Development Version dated 20211122 that includes the updates. You can follow the process outlined in the earlier topic to download and install the new Development Version. The example plugin is unchanged and does not need to be updated.

It would be great if you tried this new approach and let me know how it works for you. Thanks!

Thanks for your update with the good news on your progress. You wrote “ I have just a little problem with a blank row that appears in the table before the third control – perhaps you know why“?

The “blank row” is a result of having two [mla_term_list] shortcodes to display the second level terms, one of which is empty depending on the first level term selected. The current MLA version suppresses the control but still generates an inline “style sheet” for it. I believe this is causing the blank space. I will investigate a change to suppress the styles and see if that helps.

Regarding TranslatePress, I found this free version in the Repository:

Translate Multilingual sites – TranslatePress
By Cozmoslabs, Razvan Mocanu, Madalin Ungureanu, Cristophor Hurduban

Is that the right plugin? If so, I will try to help you solve your issue if you open a new support topic in this forum.

Thanks for catching and reporting this problem with the solution I outlined. I neglected to update the mla_link_href= parameter in the pagination controls shortcode to account for the new third-level term list. Here is the corrected parameter value:

mla_link_href="{+new_url+}?mla_paginate_current={+new_page+}&main_category={+request:main_category+}&{+template:(sub_category={+request:sub_category,url+}|third_category={+request:third_category,url+})+}"

You can see the template that selects either the second- or third-level term value depending on which is present in the request. Let me know if you have problems or further questions regarding this correction; thanks.

My apologies. I failed to test out all the combinations of the four [mla_term_list] control values and the parameter change I posted above is incorrect. I regret the inconvenience this caused you. Please give this new parameter version a try:

mla_link_href="{+new_url+}?mla_paginate_current={+new_page+}&main_category={+request:main_category+}{+template:(&include_category={+request:include_category,url+})+}{+template:(&sub_category={+request:sub_category,url+})+}{+template:(&third_category={+request:third_category,url+})+}"

You can see the updated templates that select any or all of the four term values depending on which are present in the request. Let me know if you have problems or further questions regarding this correction; thanks.

I have released MLA version 2.99, which contains the fixes developed for this topic.

I am marking the topic resolved, but please update it if you have any problems or further questions regarding the fixes described above. Thanks again for working with me on this interesting MLA application.