feat: add keepFilter option

packages/combo-box/src/vaadin-combo-box-mixin.js

@@ -867,6 +867,15 @@ export const ComboBoxMixin = (subclass) =>
       this._detectAndDispatchChange();
     }
 
+    /**
+     * Clears the current filter. Should be used instead of setting the property
+     * directly in order to allow overriding this in multi-select combo box.
+     * @protected
+     */
+    _clearFilter() {
+      this.filter = '';
+    }
+
     /**
      * Reverts back to original value.
      */
@@ -938,15 +947,15 @@ export const ComboBoxMixin = (subclass) =>
           this.value = this._getItemValue(itemMatchingInputValue);
         } else {
           // Revert the input value
-          this._inputElementValue = this.selectedItem ? this._getItemLabel(this.selectedItem) : this.value || '';
+          this._revertInputValueToValue();
         }
       }
 
       this._detectAndDispatchChange();
 
       this._clearSelectionRange();
 
-      this.filter = '';
+      this._clearFilter();
     }
 
     /**
@@ -1087,7 +1096,7 @@ export const ComboBoxMixin = (subclass) =>
         this.selectedItem = null;
       }
 
-      this.filter = '';
+      this._clearFilter();
 
       // In the next _detectAndDispatchChange() call, the change detection should pass
       this._lastCommittedValue = undefined;

packages/multi-select-combo-box/src/vaadin-multi-select-combo-box-internal.js

@@ -60,6 +60,14 @@ class MultiSelectComboBoxInternal extends ComboBoxDataProviderMixin(ComboBoxMixi
         notify: true,
       },
 
+      /**
+       * When true, filter string isn't cleared after selecting an item.
+       */
+      keepFilter: {
+        type: Boolean,
+        value: false,
+      },
+
       /**
        * When set to `true`, "loading" attribute is set
        * on the host and the overlay element.
@@ -268,6 +276,30 @@ class MultiSelectComboBoxInternal extends ComboBoxDataProviderMixin(ComboBoxMixi
     super._onEscape(event);
   }
 
+  /**
+   * Override from combo-box to ignore requests to clear the filter if the
+   * keepFilter option is enabled. Exceptions are when the dropdown is closed,
+   * so the filter is still cleared on cancel and focus out.
+   * @protected
+   * @override
+   */
+  _clearFilter() {
+    if (!this.keepFilter || !this.opened) {
+      super._clearFilter();
+    }
+  }
+
+  /**
+   * Override method from combo-box to always clear the filter when reverting
+   * the input value, regardless of the keepFilter option.
+   * @override
+   * @protected
+   */
+  _revertInputValueToValue() {
+    super._revertInputValueToValue();
+    this.filter = '';
+  }
+
   /**
    * @protected
    * @override

packages/multi-select-combo-box/src/vaadin-multi-select-combo-box.js

@@ -183,6 +183,7 @@ class MultiSelectComboBox extends ResizeMixin(InputControlMixin(ThemableMixin(El
           top-group="[[_topGroup]]"
           opened="{{opened}}"
           renderer="[[renderer]]"
+          keep-filter="[[keepFilter]]"
           theme$="[[_theme]]"
           on-combo-box-item-selected="_onComboBoxItemSelected"
           on-change="_onComboBoxChange"
@@ -305,6 +306,14 @@ class MultiSelectComboBox extends ResizeMixin(InputControlMixin(ThemableMixin(El
         type: String,
       },
 
+      /**
+       * When true, filter string isn't cleared after selecting an item.
+       */
+      keepFilter: {
+        type: Boolean,
+        value: false,
+      },
+
       /**
        * The object used to localize this component.
        * To change the default localization, replace the entire
@@ -824,10 +833,26 @@ class MultiSelectComboBox extends ResizeMixin(InputControlMixin(ThemableMixin(El
     return selectedItems.indexOf(item);
   }
 
-  /** @private */
-  __clearFilter() {
-    this.filter = '';
-    this.$.comboBox.clear();
+  /**
+   * Clear the internal combo box value and filter. Filter will not be cleared
+   * when the `keepFilter` option is enabled. Using `force` can enforce clearing
+   * the filter.
+   * @param {boolean} force overrides the keepFilter option
+   * @private */
+  __clearInternalValue(force = false) {
+    if (!this.keepFilter || force) {
+      // Clear both combo box value and filter.
+      this.filter = '';
+      this.$.comboBox.clear();
+    } else {
+      // Only clear combo box value. This effectively resets _lastCommittedValue
+      // which allows toggling the same item multiple times via keyboard.
+      this.$.comboBox.clear();
+      // Restore input to the filter value. Needed when items are
+      // navigated with keyboard, which overrides the input value
+      // with the item label.
+      this._inputElementValue = this.filter;
+    }
   }
 
   /** @private */
@@ -859,7 +884,7 @@ class MultiSelectComboBox extends ResizeMixin(InputControlMixin(ThemableMixin(El
       const lastFilter = this._lastFilter;
       // Do not unselect when manually typing and committing an already selected item.
       if (lastFilter && lastFilter.toLowerCase() === itemLabel.toLowerCase()) {
-        this.__clearFilter();
+        this.__clearInternalValue();
         return;
       }
 
@@ -872,7 +897,7 @@ class MultiSelectComboBox extends ResizeMixin(InputControlMixin(ThemableMixin(El
     this.__updateSelection(itemsCopy);
 
     // Suppress `value-changed` event.
-    this.__clearFilter();
+    this.__clearInternalValue();
 
     this.__announceItem(itemLabel, isSelected, itemsCopy.length);
   }
@@ -1232,7 +1257,7 @@ class MultiSelectComboBox extends ResizeMixin(InputControlMixin(ThemableMixin(El
     // Stop the original event
     event.stopPropagation();
 
-    this.__clearFilter();
+    this.__clearInternalValue(true);
 
     this.dispatchEvent(
       new CustomEvent('custom-value-set', {

packages/multi-select-combo-box/test/selecting-items.test.js

@@ -9,6 +9,14 @@ import { getAllItems, getDataProvider, getFirstItem } from './helpers.js';
 describe('selecting items', () => {
   let comboBox, internal, inputElement;
 
+  function expectItems(values) {
+    const items = getAllItems(comboBox);
+    expect(items.length).to.equal(values.length);
+    values.forEach((value, idx) => {
+      expect(items[idx].textContent).to.equal(value);
+    });
+  }
+
   beforeEach(() => {
     comboBox = fixtureSync(`<vaadin-multi-select-combo-box></vaadin-multi-select-combo-box>`);
     internal = comboBox.$.comboBox;
@@ -163,14 +171,6 @@ describe('selecting items', () => {
   });
 
   describe('selected items on top', () => {
-    function expectItems(values) {
-      const items = getAllItems(comboBox);
-      expect(items.length).to.equal(values.length);
-      values.forEach((value, idx) => {
-        expect(items[idx].textContent).to.equal(value);
-      });
-    }
-
     beforeEach(() => {
       comboBox.selectedItemsOnTop = true;
     });
@@ -345,4 +345,110 @@ describe('selecting items', () => {
       });
     });
   });
+
+  describe('keep filter', () => {
+    beforeEach(() => {
+      comboBox.items = ['apple', 'banana', 'lemon', 'orange'];
+      comboBox.keepFilter = true;
+    });
+
+    it('should keep the filter after selecting items', async () => {
+      await sendKeys({ type: 'an' });
+      expectItems(['banana', 'orange']);
+
+      const filterChangeSpy = sinon.spy();
+      comboBox.addEventListener('filter-changed', filterChangeSpy);
+
+      await sendKeys({ down: 'ArrowDown' });
+      await sendKeys({ down: 'Enter' });
+      expect(comboBox.selectedItems).to.deep.equal(['banana']);
+      expect(comboBox.filter).to.equal('an');
+      expect(inputElement.value).to.equal('an');
+      expectItems(['banana', 'orange']);
+      // Filter should never change, otherwise data provider would be called
+      expect(filterChangeSpy.notCalled).to.be.true;
+    });
+
+    it('should clear the filter when closing the overlay', async () => {
+      await sendKeys({ type: 'an' });
+      expectItems(['banana', 'orange']);
+
+      inputElement.blur();
+      expect(comboBox.filter).to.equal('');
+      expect(inputElement.value).to.equal('');
+    });
+
+    it('should clear a matching filter when closing the overlay', async () => {
+      await sendKeys({ type: 'apple' });
+
+      inputElement.blur();
+      expect(comboBox.selectedItems).to.deep.equal([]);
+      expect(comboBox.filter).to.equal('');
+      expect(inputElement.value).to.equal('');
+    });
+
+    it('should clear the filter when pressing escape', async () => {
+      await sendKeys({ type: 'an' });
+      expectItems(['banana', 'orange']);
+
+      await sendKeys({ down: 'Escape' });
+      expect(comboBox.filter).to.equal('');
+      expect(inputElement.value).to.equal('');
+    });
+
+    it('should clear the filter when pressing escape after selecting an item', async () => {
+      await sendKeys({ type: 'an' });
+      expectItems(['banana', 'orange']);
+
+      await sendKeys({ down: 'ArrowDown' });
+      await sendKeys({ down: 'Enter' });
+      // Pressing escape twice to first deselect item and then close the overlay
+      await sendKeys({ down: 'Escape' });
+      await sendKeys({ down: 'Escape' });
+      expect(comboBox.opened).to.be.false;
+      expect(comboBox.filter).to.equal('');
+      expect(inputElement.value).to.equal('');
+    });
+
+    it('should clear the filter when committing a non-existing item', async () => {
+      await sendKeys({ type: 'an' });
+      expectItems(['banana', 'orange']);
+
+      await sendKeys({ down: 'Enter' });
+      expect(comboBox.opened).to.be.true;
+      expect(inputElement.value).to.equal('');
+      expect(comboBox.filter).to.equal('');
+    });
+
+    it('should allow toggling items via keyboard', async () => {
+      await sendKeys({ down: 'ArrowDown' });
+      await sendKeys({ down: 'ArrowDown' });
+      await sendKeys({ down: 'Enter' });
+      expect(comboBox.selectedItems).to.deep.equal(['apple']);
+
+      await sendKeys({ down: 'Enter' });
+      expect(comboBox.selectedItems).to.deep.equal([]);
+    });
+
+    it('should restore the input value to the filter after selecting an item', async () => {
+      await sendKeys({ type: 'an' });
+      await sendKeys({ down: 'ArrowDown' });
+      await sendKeys({ down: 'Enter' });
+      expect(comboBox.selectedItems).to.deep.equal(['banana']);
+      expect(inputElement.value).to.equal('an');
+    });
+
+    describe('with allowCustomValue', () => {
+      beforeEach(() => {
+        comboBox.allowCustomValue = true;
+      });
+
+      it('should clear the filter value after entering custom value', async () => {
+        await sendKeys({ type: 'pear' });
+        await sendKeys({ down: 'Enter' });
+        expect(comboBox.filter).to.equal('');
+        expect(inputElement.value).to.equal('');
+      });
+    });
+  });
 });