fix: make explicit data request when clearing cache with no initial pool (#2119)

* fix: increase pool before clearing cache when sorting; add test

* Enhance the fix by making explicit data request

* Remove height condition

* Move the test

* Apply Serhii's suggestions

Co-authored-by: Serhii Kulykov <[email protected]>

* Update test

Co-authored-by: Serhii Kulykov <[email protected]>

Author: yuriy-fix

src/vaadin-grid-data-provider-mixin.js

@@ -420,7 +420,7 @@ export const DataProviderMixin = (superClass) =>
       this._hasData = false;
       this._assignModels();
 
-      if (!this._effectiveSize) {
+      if (!this._effectiveSize || !this._initialPoolCreated) {
         this._loadPage(0, this._cache);
       }
     }

test/data-provider.test.js

@@ -8,6 +8,7 @@ import {
   getCellContent,
   getContainerCell,
   getFirstCell,
+  getFirstVisibleItem,
   getRows,
   getRowCells,
   infiniteDataProvider,
@@ -563,6 +564,32 @@ describe('data provider', () => {
   });
 });
 
+describe('attached', () => {
+  it('should have rows when attached and shown after cache is cleared on hidden grid', async () => {
+    const grid = document.createElement('vaadin-grid');
+    const col = document.createElement('vaadin-grid-column');
+    col.setAttribute('path', 'item');
+    grid.appendChild(col);
+
+    grid.size = 1;
+    grid.dataProvider = function (params, callback) {
+      callback([{ item: 'A' }]);
+    };
+
+    grid.style.display = 'none';
+    document.body.appendChild(grid);
+
+    await aTimeout(0);
+
+    grid.clearCache();
+    grid.removeAttribute('style');
+    expect(getCellContent(getFirstVisibleItem(grid)).textContent).to.equal('A');
+
+    // Grid should be removed after test as was attached to body.
+    document.body.removeChild(grid);
+  });
+});
+
 describe('page size grid', () => {
   it('should render grid rows when setting page-size before size', () => {
     const container = fixtureSync('<page-size-grid></page-size-grid>');