novice, who is trying to write a project by himself with flask, uses bootstrap-select "s drop-down multi-selection menu to pass parameters from the background to option display list. There is no problem with the multi-selection function, but he does not know how to pass multiple options selected by the user to the background for advice.

the template is as follows:

<div class="selector">
    <select class="selectpicker" multiple data-live-search="true" data-selected-text-format="count > 3" data-actions-box="true">
    {% for HI in HIs %}
        <option value="{{ user.username }}">{{ user.username }}</option>
    {% endfor %}
    </select>
</div>