Stable multi-select implementation

src/jinja/select.html.jinja

@@ -2,8 +2,10 @@
   Renders a select or combobox component.
 
   @param id {string} [optional] - Unique identifier for the select component.
-  @param selected {string} [optional] - The initially selected value.
+  @param selected {string|array} [optional] - The initially selected value(s).
   @param name {string} [optional] - The name attribute for the hidden input storing the selected value.
+  @param multiple {boolean} [optional] [default=false] - Enables multiple selection mode.
+  @param placeholder {string} [optional] - Placeholder text shown when no options are selected (multiple mode only).
   @param main_attrs {object} [optional] - Additional HTML attributes for the main container div.
   @param trigger_attrs {object} [optional] - Additional HTML attributes for the trigger button.
   @param popover_attrs {object} [optional] - Additional HTML attributes for the popover content div.
@@ -17,6 +19,8 @@
   selected=None,
   name=None,
   items=[],
+  multiple=false,
+  placeholder=None,
   main_attrs={},
   trigger_attrs={},
   popover_attrs={},
@@ -27,8 +31,9 @@
 ) %}
 {% set id = id or ("select-" + (range(100000, 999999) | random | string)) %}
 
+{% set selectedArray = ((selected if (selected is iterable and selected is not string) else [selected]) if selected else []) %}
 {% set first_option = namespace(item=None) %}
-{% set selected_option = namespace(item=None) %}
+{% set selected_options = namespace(items=[]) %}
 
 {% if items %}
   {% for item in items %}
@@ -37,26 +42,34 @@
         {% if not first_option.item %}
           {% set first_option.item = sub_item %}
         {% endif %}
-        {% if selected and sub_item.value == selected and not selected_option.item %}
-          {% set selected_option.item = sub_item %}
+        {% if sub_item.value in selectedArray %}
+          {% set selected_options.items = selected_options.items + [sub_item] %}
         {% endif %}
       {% endfor %}
     {% else %}
       {% if not first_option.item %}
         {% set first_option.item = item %}
       {% endif %}
-      {% if selected and item.value == selected and not selected_option.item %}
-        {% set selected_option.item = item %}
+      {% if item.value in selectedArray %}
+        {% set selected_options.items = selected_options.items + [item] %}
       {% endif %}
     {% endif %}
   {% endfor %}
 {% endif %}
 
-{% set default_option = selected_option.item or first_option.item or None %}
+{% set default_option = (selected_options.items[0] if selected_options.items else first_option.item) %}
+{% set labels = [] %}
+{% if multiple and selected_options.items %}
+  {% for opt in selected_options.items %}
+    {% set labels = labels + [opt.label] %}
+  {% endfor %}
+{% endif %}
+{% set default_label = (', '.join(labels) if (multiple and selected_options.items) else ((placeholder or '') if (multiple and not selected_options.items) else (default_option.label if default_option else ''))) %}
 
 <div
   id="{{ id }}"
   class="select {{ main_attrs.class }}"
+  {% if multiple and placeholder %}data-placeholder="{{ placeholder }}"{% endif %}
   {% for key, value in main_attrs.items() %}
     {% if key != 'class' %}{{ key }}="{{ value }}"{% endif %}
   {% endfor %}
@@ -72,7 +85,7 @@
       {% if key != 'class' %}{{ key }}="{{ value }}"{% endif %}
     {% endfor %}
   >
-    <span class="truncate">{{ default_option.label }}</span>
+    <span class="truncate">{{ default_label }}</span>
     {% if is_combobox %}
       <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-chevrons-up-down-icon lucide-chevrons-up-down text-muted-foreground opacity-50 shrink-0"><path d="m7 15 5 5 5-5"/><path d="m7 9 5-5 5 5"/></svg>
     {% else %}
@@ -110,25 +123,40 @@
       id="{{ id }}-listbox"
       aria-orientation="vertical"
       aria-labelledby="{{ id }}-trigger"
+      {% if multiple %}aria-multiselectable="true"{% endif %}
       {% for key, value in listbox_attrs.items() %}
         {{ key }}="{{ value }}"
       {% endfor %}
     >
       {% if items %}
-        {{ render_select_items(items, default_option.value, id ~ "-items" if id else "items") }}
+        {{ render_select_items(items, selectedArray, id ~ "-items" if id else "items") }}
       {% else %}
         {{ caller() if caller }}
       {% endif %}
     </div>
   </div>
-  <input
-    type="hidden"
-    name="{{ name or id ~ '-value' }}"
-    value="{{ (default_option.value if default_option) or '' }}"
-    {% for key, value in input_attrs.items() %}
-      {% if key != 'name' and key != 'value' %}{{ key }}="{{ value }}"{% endif %}
+  {% if multiple and selectedArray %}
+    {% for val in selectedArray %}
+      <input
+        type="hidden"
+        name="{{ name or id ~ '-value' }}"
+        value="{{ val }}"
+        {% if loop.index0 > 0 %}id="{{ id }}-value-{{ loop.index0 }}"{% endif %}
+        {% for key, value in input_attrs.items() %}
+          {% if key != 'name' and key != 'value' %}{{ key }}="{{ value }}"{% endif %}
+        {% endfor %}
+      >
     {% endfor %}
-  >
+  {% else %}
+    <input
+      type="hidden"
+      name="{{ name or id ~ '-value' }}"
+      value="{{ (default_option.value if default_option) or '' }}"
+      {% for key, value in input_attrs.items() %}
+        {% if key != 'name' and key != 'value' %}{{ key }}="{{ value }}"{% endif %}
+      {% endfor %}
+    >
+  {% endif %}
 </div>
 {% endmacro %}
 
@@ -138,7 +166,7 @@
   @param items {array} - The array of items to render.
   @param parent_id_prefix {string} [optional] - The prefix for the item id.
 #}
-{% macro render_select_items(items, selected, parent_id_prefix="items") %}
+{% macro render_select_items(items, selectedArray, parent_id_prefix="items") %}
   {% for item in items %}
     {% set item_id = parent_id_prefix ~ "-" ~ loop.index %}
     {% if item.type == "group" %}
@@ -153,7 +181,7 @@
         {% endif %}
       >
         <div role="heading" id="{{ group_label_id }}">{{ item.label }}</div>
-        {{ render_select_items(item['items'], selected, item_id) if item['items'] }}
+        {{ render_select_items(item['items'], selectedArray, item_id) if item['items'] }}
       </div>
     {% elif item.type == "separator" %}
       <hr role="separator" />
@@ -162,7 +190,7 @@
         id="{{ item_id }}"
         role="option"
         data-value="{{ item.value }}"
-        {% if selected == item.value %}aria-selected="true"{% endif %}
+        {% if item.value in selectedArray %}aria-selected="true"{% endif %}
         {% if item.attrs %}
           {% for key, value in item.attrs.items() %}
             {{ key }}="{{ value }}"

src/js/select.js

@@ -3,23 +3,31 @@
     const trigger = selectComponent.querySelector(':scope > button');
     const selectedLabel = trigger.querySelector(':scope > span');
     const popover = selectComponent.querySelector(':scope > [data-popover]');
-    const listbox = popover.querySelector('[role="listbox"]');
+    const listbox = popover ? popover.querySelector('[role="listbox"]') : null;
     const input = selectComponent.querySelector(':scope > input[type="hidden"]');
     const filter = selectComponent.querySelector('header input[type="text"]');
+
     if (!trigger || !popover || !listbox || !input) {
       const missing = [];
       if (!trigger) missing.push('trigger');
       if (!popover) missing.push('popover');
       if (!listbox) missing.push('listbox');
-      if (!input)   missing.push('input');
+      if (!input) missing.push('input');
       console.error(`Select component initialisation failed. Missing element(s): ${missing.join(', ')}`, selectComponent);
       return;
     }
-    
+
     const allOptions = Array.from(listbox.querySelectorAll('[role="option"]'));
     const options = allOptions.filter(opt => opt.getAttribute('aria-disabled') !== 'true');
     let visibleOptions = [...options];
     let activeIndex = -1;
+    const isMultiple = listbox.getAttribute('aria-multiselectable') === 'true';
+    let selectedValues = isMultiple ? new Set() : null;
+    let placeholder = null;
+
+    if (isMultiple) {
+      placeholder = selectComponent.dataset.placeholder || '';
+    }
 
     const setActiveOption = (index) => {
       if (activeIndex > -1 && options[activeIndex]) {
@@ -46,13 +54,46 @@
       return parseFloat(style.transitionDuration) > 0 || parseFloat(style.transitionDelay) > 0;
     };
 
+    const syncMultipleInputs = () => {
+      if (!isMultiple) return;
+      const values = Array.from(selectedValues);
+      const inputs = Array.from(selectComponent.querySelectorAll(':scope > input[type="hidden"]'));
+      inputs.slice(1).forEach(inp => inp.remove());
+
+      if (values.length === 0) {
+        input.value = '';
+      } else {
+        input.value = values[0];
+        let insertAfter = input;
+        for (let i = 1; i < values.length; i++) {
+          const clone = input.cloneNode(true);
+          clone.removeAttribute('id');
+          clone.value = values[i];
+          insertAfter.after(clone);
+          insertAfter = clone;
+        }
+      }
+    };
+
+    const updateMultipleLabel = () => {
+      if (!isMultiple) return;
+      const selected = options.filter(opt => selectedValues.has(opt.dataset.value));
+      if (selected.length === 0) {
+        selectedLabel.textContent = placeholder;
+        selectedLabel.classList.add('text-muted-foreground');
+      } else {
+        selectedLabel.textContent = selected.map(opt => opt.dataset.label || opt.textContent.trim()).join(', ');
+        selectedLabel.classList.remove('text-muted-foreground');
+      }
+    };
+
     const updateValue = (option, triggerEvent = true) => {
       if (option) {
         selectedLabel.innerHTML = option.innerHTML;
         input.value = option.dataset.value;
         listbox.querySelector('[role="option"][aria-selected="true"]')?.removeAttribute('aria-selected');
         option.setAttribute('aria-selected', 'true');
-        
+
         if (triggerEvent) {
           const event = new CustomEvent('change', {
             detail: { value: option.dataset.value },
@@ -63,6 +104,35 @@
       }
     };
 
+    const toggleMultipleValue = (value, triggerEvent = true) => {
+      if (!isMultiple || value == null) return;
+
+      if (selectedValues.has(value)) {
+        selectedValues.delete(value);
+      } else {
+        selectedValues.add(value);
+      }
+
+      options.forEach(opt => {
+        if (selectedValues.has(opt.dataset.value)) {
+          opt.setAttribute('aria-selected', 'true');
+        } else {
+          opt.removeAttribute('aria-selected');
+        }
+      });
+
+      updateMultipleLabel();
+      syncMultipleInputs();
+
+      if (triggerEvent) {
+        const event = new CustomEvent('change', {
+          detail: { value, values: Array.from(selectedValues) },
+          bubbles: true
+        });
+        selectComponent.dispatchEvent(event);
+      }
+    };
+
     const closePopover = (focusOnTrigger = true) => {
       if (popover.getAttribute('aria-hidden') === 'true') return;
       
@@ -101,7 +171,59 @@
 
     const selectByValue = (value) => {
       const option = options.find(opt => opt.dataset.value === value);
-      selectOption(option);
+      if (isMultiple) {
+        if (option && value != null) {
+          selectedValues.add(value);
+          options.forEach(opt => {
+            if (selectedValues.has(opt.dataset.value)) {
+              opt.setAttribute('aria-selected', 'true');
+            } else {
+              opt.removeAttribute('aria-selected');
+            }
+          });
+          updateMultipleLabel();
+          syncMultipleInputs();
+          const event = new CustomEvent('change', {
+            detail: { value, values: Array.from(selectedValues) },
+            bubbles: true
+          });
+          selectComponent.dispatchEvent(event);
+        }
+      } else {
+        selectOption(option);
+      }
+    };
+
+    const selectAll = () => {
+      if (!isMultiple) return;
+      selectedValues = new Set(options.map(opt => opt.dataset.value).filter(v => v != null));
+      options.forEach(opt => {
+        if (selectedValues.has(opt.dataset.value)) {
+          opt.setAttribute('aria-selected', 'true');
+        } else {
+          opt.removeAttribute('aria-selected');
+        }
+      });
+      updateMultipleLabel();
+      syncMultipleInputs();
+      const event = new CustomEvent('change', {
+        detail: { values: Array.from(selectedValues) },
+        bubbles: true
+      });
+      selectComponent.dispatchEvent(event);
+    };
+
+    const selectNone = () => {
+      if (!isMultiple) return;
+      selectedValues.clear();
+      options.forEach(opt => opt.removeAttribute('aria-selected'));
+      updateMultipleLabel();
+      syncMultipleInputs();
+      const event = new CustomEvent('change', {
+        detail: { values: [] },
+        bubbles: true
+      });
+      selectComponent.dispatchEvent(event);
     };
 
     if (filter) {
@@ -137,13 +259,40 @@
       filter.addEventListener('input', filterOptions);
     }
 
-    let initialOption = options.find(opt => opt.dataset.value === input.value);
-    
-    if (!initialOption) {
-      initialOption = options.find(opt => opt.dataset.value !== undefined) ?? options[0];
-    }
+    if (isMultiple) {
+      const validValues = new Set(options.map(opt => opt.dataset.value).filter(v => v != null));
+      const inputs = Array.from(selectComponent.querySelectorAll(':scope > input[type="hidden"]'));
+      const initialValues = inputs
+        .map(inp => inp.value)
+        .filter(v => v != null && validValues.has(v));
+      if (initialValues.length > 0) {
+        initialValues.forEach(val => selectedValues.add(val));
+      } else {
+        const preSelected = options.filter(opt => opt.getAttribute('aria-selected') === 'true');
+        if (preSelected.length > 0) {
+          preSelected.forEach(opt => opt.dataset.value != null && selectedValues.add(opt.dataset.value));
+        }
+      }
+      options.forEach(opt => {
+        if (selectedValues.has(opt.dataset.value)) {
+          opt.setAttribute('aria-selected', 'true');
+        } else {
+          opt.removeAttribute('aria-selected');
+        }
+      });
+      updateMultipleLabel();
+      syncMultipleInputs();
+    } else {
+      let initialOption = options.find(opt => opt.dataset.value === input.value);
 
-    updateValue(initialOption, false);
+      if (!initialOption) {
+        initialOption = options.find(opt => opt.dataset.value !== undefined) ?? options[0];
+      }
+
+      if (initialOption) {
+        updateValue(initialOption, false);
+      }
+    }
 
     const handleKeyNavigation = (event) => {
       const isPopoverOpen = popover.getAttribute('aria-hidden') === 'false';
@@ -169,7 +318,11 @@
       
       if (event.key === 'Enter') {
         if (activeIndex > -1) {
-          selectOption(options[activeIndex]);
+          if (isMultiple) {
+            toggleMultipleValue(options[activeIndex].dataset.value);
+          } else {
+            selectOption(options[activeIndex]);
+          }
         }
         return;
       }
@@ -268,7 +421,11 @@
     listbox.addEventListener('click', (event) => {
       const clickedOption = event.target.closest('[role="option"]');
       if (clickedOption) {
-        selectOption(clickedOption);
+        if (isMultiple) {
+          toggleMultipleValue(clickedOption.dataset.value);
+        } else {
+          selectOption(clickedOption);
+        }
       }
     });
 
@@ -285,8 +442,12 @@
     });
 
     popover.setAttribute('aria-hidden', 'true');
-    
+
     selectComponent.selectByValue = selectByValue;
+    if (isMultiple) {
+      selectComponent.selectAll = selectAll;
+      selectComponent.selectNone = selectNone;
+    }
     selectComponent.dataset.selectInitialized = true;
     selectComponent.dispatchEvent(new CustomEvent('basecoat:initialized'));
   };

src/nunjucks/select.njk

@@ -2,8 +2,10 @@
   Renders a select or combobox component.
 
   @param id {string} [optional] - Unique identifier for the select component.
-  @param selected {string} [optional] - The initially selected value.
+  @param selected {string|array} [optional] - The initially selected value(s).
   @param name {string} [optional] - The name attribute for the hidden input storing the selected value.
+  @param multiple {boolean} [optional] [default=false] - Enables multiple selection mode.
+  @param placeholder {string} [optional] - Placeholder text shown when no options are selected (multiple mode only).
   @param main_attrs {object} [optional] - Additional HTML attributes for the main container div.
   @param trigger_attrs {object} [optional] - Additional HTML attributes for the trigger button.
   @param popover_attrs {object} [optional] - Additional HTML attributes for the popover content div.
@@ -17,6 +19,8 @@
   selected=None,
   name=None,
   items=None,
+  multiple=false,
+  placeholder=None,
   main_attrs={},
   trigger_attrs={},
   popover_attrs={},
@@ -27,8 +31,9 @@
 ) %}
 {% set id = id or ("select-" + (range(100000, 999999) | random | string)) %}
 
+{% set selectedArray = ((selected if (selected is iterable and selected is not string) else [selected]) if selected else []) %}
 {% set first_option = [] %}
-{% set selected_option = [] %}
+{% set selected_options = [] %}
 
 {% if items %}
   {% for item in items %}
@@ -37,26 +42,34 @@
         {% if not first_option[0] %}
           {% set first_option = (first_option.push(sub_item), first_option) %}
         {% endif %}
-        {% if selected and sub_item.value == selected and not selected_option[0] %}
-          {% set selected_option = (selected_option.push(sub_item), selected_option) %}
+        {% if sub_item.value in selectedArray %}
+          {% set selected_options = (selected_options.push(sub_item), selected_options) %}
         {% endif %}
       {% endfor %}
     {% else %}
       {% if not first_option[0] %}
         {% set first_option = (first_option.push(item), first_option) %}
       {% endif %}
-      {% if selected and item.value == selected and not selected_option[0] %}
-        {% set selected_option = (selected_option.push(item), selected_option) %}
+      {% if item.value in selectedArray %}
+        {% set selected_options = (selected_options.push(item), selected_options) %}
       {% endif %}
     {% endif %}
   {% endfor %}
 {% endif %}
 
-{% set default_option = selected_option[0] or first_option[0] or None %}
+{% set default_option = (selected_options[0] if selected_options[0] else (first_option[0] if first_option[0] else None)) %}
+{% set labels = [] %}
+{% if multiple and selected_options %}
+  {% for opt in selected_options %}
+    {% set labels = (labels.push(opt.label), labels) %}
+  {% endfor %}
+{% endif %}
+{% set default_label = (labels | join(', ') if (multiple and selected_options) else ((placeholder or '') if (multiple and not selected_options) else (default_option.label if default_option else ''))) %}
 
 <div
   id="{{ id }}"
   class="select {{ main_attrs.class }}"
+  {% if multiple and placeholder %}data-placeholder="{{ placeholder }}"{% endif %}
   {% for key, value in main_attrs %}
     {% if key != 'class' %}{{ key }}="{{ value }}"{% endif %}
   {% endfor %}
@@ -72,7 +85,7 @@
       {% if key != 'class' %}{{ key }}="{{ value }}"{% endif %}
     {% endfor %}
   >
-    <span class="truncate">{{ default_option.label }}</span>
+    <span class="truncate">{{ default_label }}</span>
     {% if is_combobox %}
       <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-chevrons-up-down-icon lucide-chevrons-up-down text-muted-foreground opacity-50 shrink-0"><path d="m7 15 5 5 5-5"/><path d="m7 9 5-5 5 5"/></svg>
     {% else %}
@@ -110,25 +123,40 @@
       id="{{ id }}-listbox"
       aria-orientation="vertical"
       aria-labelledby="{{ id }}-trigger"
+      {% if multiple %}aria-multiselectable="true"{% endif %}
       {% for key, value in listbox_attrs %}
         {{ key }}="{{ value }}"
       {% endfor %}
     >
       {% if items and items.length > 0 %}
-        {{ render_select_items(items, default_option.value, id ~ "-items" if id else "items") }}
+        {{ render_select_items(items, selectedArray, id ~ "-items" if id else "items") }}
       {% else %}
         {{ caller() if caller }}
       {% endif %}
     </div>
   </div>
-  <input
-    type="hidden"
-    name="{{ name or id ~ '-value' }}"
-    value="{{ (default_option.value if default_option) or '' }}"
-    {% for key, value in input_attrs %}
-      {% if key != 'name' and key != 'value' %}{{ key }}="{{ value }}"{% endif %}
+  {% if multiple and selectedArray %}
+    {% for val in selectedArray %}
+      <input
+        type="hidden"
+        name="{{ name or id ~ '-value' }}"
+        value="{{ val }}"
+        {% if loop.index0 > 0 %}id="{{ id }}-value-{{ loop.index0 }}"{% endif %}
+        {% for key, value in input_attrs %}
+          {% if key != 'name' and key != 'value' %}{{ key }}="{{ value }}"{% endif %}
+        {% endfor %}
+      >
     {% endfor %}
-  >
+  {% else %}
+    <input
+      type="hidden"
+      name="{{ name or id ~ '-value' }}"
+      value="{{ (default_option.value if default_option) or '' }}"
+      {% for key, value in input_attrs %}
+        {% if key != 'name' and key != 'value' %}{{ key }}="{{ value }}"{% endif %}
+      {% endfor %}
+    >
+  {% endif %}
 </div>
 {% endmacro %}
 
@@ -138,7 +166,7 @@
   @param items {array} - The array of items to render.
   @param parent_id_prefix {string} [optional] - The prefix for the item id.
 #}
-{% macro render_select_items(items, selected, parent_id_prefix="items") %}
+{% macro render_select_items(items, selectedArray, parent_id_prefix="items") %}
   {% for item in items %}
     {% set item_id = parent_id_prefix ~ "-" ~ loop.index %}
     {% if item.type == "group" %}
@@ -153,7 +181,7 @@
         {% endif %}
       >
         <div role="heading" id="{{ group_label_id }}">{{ item.label }}</div>
-        {{ render_select_items(item.items, selected, item_id) if item.items }}
+        {{ render_select_items(item.items, selectedArray, item_id) if item.items }}
       </div>
     {% elif item.type == "separator" %}
       <hr role="separator" />
@@ -162,7 +190,7 @@
         id="{{ item_id }}"
         role="option"
         data-value="{{ item.value }}"
-        {% if selected == item.value %}aria-selected="true"{% endif %}
+        {% if item.value in selectedArray %}aria-selected="true"{% endif %}
         {% if item.attrs %}
           {% for key, value in item.attrs %}
             {{ key }}="{{ value }}"