structure-meta-info

name	structure-meta-info
description	Adding custom fields to articles, categories, media, and clang via the REDAXO meta_info plugin. Use when the user adds custom metadata to structure entities (e.g. SEO fields, badges, taxonomies), edits prefix conventions, or programmatically reads meta values.

Meta Info

The structure/meta_info plugin (ships with the structure addon) lets you add custom fields to:

• Articles (art_* prefix)
• Categories (cat_* prefix)
• Media (med_* prefix)
• Languages / clang (clang_* prefix)

Fields are configured in the backend (Structure → Meta-Information). Each field has a name (matches the SQL column), a label, a type (text, textarea, select, radio, checkbox, media/medialist/link/linklist picker, date, datetime, time, legend), and an optional default. The full list of type_id constants lives in rex_metainfo_default_type — see the redaxo-metainfo-fields skill for the reference table.

The prefix tells REDAXO which entity it belongs to – art_my_field adds a column to rex_article, cat_my_field adds it to rex_article (categories share the table), med_my_field extends rex_media.

Reading meta values

// On articles
$article = rex_article::getCurrent();
$value = $article->getValue('art_subtitle');

// On categories
$cat = rex_category::getCurrent();
$value = $cat->getValue('cat_color');

// On media
$media = rex_media::get('hero.jpg');
$copyright = $media->getValue('med_copyright');

// On clang
$clang = rex_clang::getCurrent();
$value = $clang->getValue('clang_currency');

getValue() returns the raw column value as a string. Cast as needed:

$boolField = (bool) (int) $article->getValue('art_featured');
$intField  = (int) $article->getValue('art_priority_score');

Setting meta values programmatically

Through the article/category service so changes are tracked:

rex_article_service::editArticle($articleId, $clangId, [
    'art_subtitle' => 'A new subtitle',
    'art_featured' => 1,
]);

For media, use rex_media_service::updateMedia(). For clang, write directly via rex_sql (no service wrapper exists for clang updates):

$sql = rex_sql::factory();
$sql->setTable(rex::getTable('clang'));
$sql->setWhere(['id' => $clangId]);
$sql->setValue('clang_currency', 'EUR');
$sql->update();
rex_clang::reset(); // clear in-process clang cache

Adding meta fields programmatically (in install.php)

The meta_info plugin exposes a small API for declaring fields without clicking through the backend. This is the right approach for distributable addons.

The target table is derived from the field name's prefix (art_* → articles, cat_* → categories, med_* → media, clang_* → languages); there is no explicit table argument. Parameter order is (title, name, priority, attributes, type, default, params, validate, restrictions, callback):

<?php
// install.php
if (rex_plugin::get('structure', 'meta_info')->isAvailable()) {
    rex_metainfo_add_field(
        'Subtitle',                              // $title (backend label)
        'art_subtitle',                          // $name (prefix decides the target table)
        100,                                     // $priority
        '',                                      // $attributes (raw input attrs)
        rex_metainfo_default_type::TEXT,         // $type
        '',                                      // $default
        null,                                    // $params (option list for SELECT/RADIO/CHECKBOX)
        null,                                    // $validate
        '',                                      // $restrictions (role/perm string, '' = visible to all)
    );
}

The full constants list is in the redaxo-metainfo-fields skill. For an idempotent re-runnable variant (the function silently no-ops if the field already exists), see the pattern documented there.

To remove a field on uninstall:

<?php
// uninstall.php
if (rex_plugin::get('structure', 'meta_info')->isAvailable()) {
    rex_metainfo_delete_field('art_subtitle');
}

Common SEO meta fields

YRewrite ships these by default; they're already added when YRewrite is installed:

• art_yrewrite_title – page title override
• art_yrewrite_description – meta description
• art_yrewrite_index – index / noindex
• art_yrewrite_canonical_url – canonical override
• art_yrewrite_image – social-share image (REX_MEDIA_WIDGET)

Don't redefine them in your own addon.

Filtering by meta in queries

Meta fields are real columns on rex_article (or rex_media/rex_clang), so you can query them with rex_sql:

$sql = rex_sql::factory();
$sql->setQuery(
    'SELECT id FROM ' . rex::getTable('article') . '
     WHERE clang_id = :clang
       AND status = 1
       AND art_featured = 1
     ORDER BY priority',
    ['clang' => rex_clang::getCurrentId()]
);

For dropdowns (type_id 3) the value stored is the option key, not the label. Decoding labels requires re-reading the field config:

$sql = rex_sql::factory();
$sql->setQuery(
    'SELECT params FROM ' . rex::getTable('metainfo_field') . '
     WHERE name = ?',
    ['art_status']
);
$params = $sql->getValue('params'); // "1,Draft|2,Review|3,Published"

Common pitfalls

• Forgetting the prefix – subtitle won't work; it must be art_subtitle.
• Adding meta fields with rex_sql directly instead of rex_metainfo_add_field – the form in the backend doesn't show them.
• Querying by meta value before checking that the field exists across versions – migration scripts should always ensureColumn() first.
• Using meta_info for many-to-many data – it's column-per-field. For tags, related entries, etc. use a YForm relation table.
• Treating dropdown values as labels in templates – they're the option keys. Map back to labels via params or store labels redundantly.