PR for Issue #30288

Summary of Changes

As explained with the issue at hand, the choices.js provides support for a render limit of the options and a search results limit, the first is much more important.

• build/media_source/system/js/fields/joomla-field-fancy-select.w-c.es6.js now can use render-limit and results-limit attributes to set searchResultLimit and renderChoiceLimit options for choices.js;
• libraries/src/Form/Field/ListField.php now can properly add the renderLimit and resultsLimit attributes from layout;
• layouts/joomla/form/field/list-fancy-select.php can now add the render-limit and results-limit HTML attributes to the element from the layout set renderLimit and resultsLimit field properties.

Alternative solution
Since the issue we're trying to solve is the slow initialization for large lists, we can simply replace searchResultLimit with renderChoiceLimit with the same value of 10 in build/media_source/system/js/fields/joomla-field-fancy-select.w-c.es6.js. The user would expect a search to take some time, but an initialization cannot take 2-3 seconds per field. This however won't give developers much flexibility.

Testing Instructions

• Open any extensionName.xml and add this field in any <fieldset>

    <field
      name="fancy-select"
      type="List"
      label="List Demo"
      default="5"
      renderLimit="5"
      resultsLimit="15"
      layout="joomla.form.field.list-fancy-select">
      <option value="0">zr</option>
      <option value="1">zr 1</option>
      <option value="2">zr 2</option>
      <option value="3">zr 3</option>
      <option value="4">zr 4</option>
      <option value="5">zr 5</option>
      <option value="6">zr 6</option>
      <option value="7">zr 7</option>
      <option value="8">zr 8</option>
      <option value="9">zr 9</option>
      <option value="10">ze 10</option>
      <option value="11">ze 11</option>
      <option value="12">ze 12</option>
      <option value="13">ze 13</option>
      <option value="14">ze 14</option>
      <option value="15">ze 15</option>
      <option value="16">ze 16</option>
      <option value="17">ze 18</option>
      <option value="18">ze 18</option>
      <option value="19">ze 19</option>
      <option value="20">zt 20</option>
      <option value="21">zt 21</option>
      <option value="22">zt 22</option>
      <option value="23">zt 23</option>
      <option value="24">zt 24</option>
      <option value="25">zt 25</option>
      <option value="26">zt 26</option>
      <option value="27">zt 27</option>
      <option value="28">zt 28</option>
      <option value="29">zt 29</option>
      <option value="30">zt 30</option>
    </field>

• save and go to that extension config
• open the field dropdown, there should be 5 options as configured;
• type in 'Z' in the search box of the field, you should get 15 results as configured.

Actual result BEFORE applying this Pull Request

Large lists are initialized extremely slow, also the initial resultsLimit of 10 was not enough. Imagine more than 10 Roboto font family styles, or much more articles that contain a certain keyword / combination of keywords.

Expected result AFTER applying this Pull Request

Much faster initialization, also more flexible PHP extend possibilities.

Documentation Changes Required

Yes.