When clicking on a provider, on the global search result list, add all results from this provider to the playlist.

Fixes issue 3132.

src/globalsearch/globalsearchmodel.cpp

@@ -240,6 +240,23 @@ void GlobalSearchModel::GetChildResults(
     QVariant result = item->data(Role_Result);
     if (result.isValid()) {
       results->append(result.value<SearchProvider::Result>());
+    } else {
+      // Maybe it's a provider then?
+      bool is_provider;
+      const int sort_index = item->data(Role_ProviderIndex).toInt(&is_provider);
+      if (is_provider) {
+        // Go through all the items (through the proxy to keep them ordered) and
+        // add the ones belonging to this provider to our list
+        for (int i = 0; i < proxy_->rowCount(invisibleRootItem()->index()); ++i) {
+          QModelIndex child_index =
+              proxy_->index(i, 0, invisibleRootItem()->index());
+          const QStandardItem* child_item =
+              itemFromIndex(proxy_->mapToSource(child_index));
+          if (child_item->data(Role_ProviderIndex).toInt() == sort_index) {
+            GetChildResults(child_item, results, visited);
+          }
+        }
+      }
     }
   }
 }