Duplicate Post, SEO plugins and site search

Three small integrations that make fields behave like the rest of WordPress.

Duplicated posts

Field values are not post meta, so a plain "copy the post meta" duplicator leaves the copy with empty fields. The plugin copies the field rows when:

• Yoast Duplicate Post (the plugin called "Yoast Duplicate Post") is active. It is detected automatically, nothing to configure. The values follow the copy for Clone, New Draft (the hooks dp_duplicate_post, dp_duplicate_page and duplicate_post_post_copy) and Rewrite & Republish (duplicate_post_after_rewriting). With Rewrite & Republish the values of the copy are merged back into the original when the copy is republished.
• Another duplicator calls the action wpmcf/fields/copy_object itself.

// After your own code created a copy of a post:
do_action( 'wpmcf/fields/copy_object', $original_id, $copy_id );

What the copy does:

WPML's own duplicate function is covered by the multilingual integration (Business). More about moving values (WXR export and import, duplicates): WordPress export files and duplicates.

SEO variables

Every active field group makes its fields available as variables in the title and description templates of Yoast SEO and Rank Math. No setting is needed.

Two underscores separate the group key from the field key, and the group key is used in full (a group wpmcf_x gives wpmcf_wpmcf_x__field). Use them in Search appearance templates (Yoast), Titles & Meta (Rank Math) or in a single post's SEO box:

%%title%% - %%wpmcf_book_details__subtitle%% %%sep%% %%sitename%%

In Yoast the variables are listed under the Advanced variables; the help text is Field label (Group label). In Rank Math the variable's name is the same text and its example is the field label.

What a variable returns:

Other types use the field type's own output format (the same one wpmcf_the_field() prints) with the tags stripped; the result is always plain text. Repeaters, groups and similar containers were not tested and are best not used in titles.

Rules:

• Top-level fields with a column only. Password fields are never offered.
• Maximum 200 variables in total, so a very large setup does not flood the SEO plugins' lists; the groups are taken in order.
• On a single post or page the variable uses that post. On archives the post only counts inside the loop; outside it the variable is empty (the SEO plugin may ask for a specific post, which is used when it passes one).
• Variables are registered only while the SEO plugin is active. Inactive groups are not offered.
• A failure in a variable prints nothing and is logged under integration.yoast or integration.rank-math; it never breaks the page.

Site search

The WordPress search (?s=...) looks in the title, excerpt and content. Switch on Include in site search in a group (Settings, Group settings tab) and it also looks in the group's text fields.

"settings": { "searchable": true }

Which fields are searched: Text, Text area, WYSIWYG editor, Email, URL and Select. A Select is searched by its stored value, not its label (searching Alpha did not find a field whose value is a; searching a did). Numbers, True / False, Checkbox, Repeater, Group, Relationship, Password and other fields are not searched.

How it behaves (verified on a front-end search):

Notes:

• It applies to front-end searches (a WP_Query with s, where is_search() is true). The admin list screens' search is not changed.
• It adds a condition to the clause core builds for each word. If another plugin rewrote that clause (a search-replacement plugin such as a relevance plugin), that word is left alone.
• The order of results is whatever core or your theme gives; field matches do not change relevance.
• It uses LIKE '%word%' on the field columns, which cannot use an index. On very large tables, search can become slow; keep the number of searchable groups small.
• Only posts. Users, terms and comments are not searched.

Troubleshooting