Doc: improve Using Model Indexes in Model View Programming guide

The current example using QFileSystemModel doesn't take into account the
asynchronous nature of that model. This puts people on the wrong path on
how to use it.

This patch improves the snippet as well as the explanation steps.

Change-Id: I5c7a3c19aad48847f0b965b5eb69b492d6263f51
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

1 files changed, 5 insertions, 2 deletions

diff --git a/src/widgets/doc/snippets/simplemodel-use/main.cpp b/src/widgets/doc/snippets/simplemodel-use/main.cpp
index 3e106c8eea..940669e101 100644
--- a/src/widgets/doc/snippets/simplemodel-use/main.cpp
+++ b/src/widgets/doc/snippets/simplemodel-use/main.cpp
@@ -79,8 +79,11 @@ int main(int argc, char *argv[])
 
 //! [0]
     QFileSystemModel *model = new QFileSystemModel;
-    QModelIndex parentIndex = model->index(QDir::currentPath());
-    int numRows = model->rowCount(parentIndex);
+    connect(model, &QFileSystemModel::directoryLoaded, [model](const QString &directory) {
+        QModelIndex parentIndex = model->index(directory);
+        int numRows = model->rowCount(parentIndex);
+    });
+    model->setRootPath(QDir::currentPath);
 //! [0]
 
 //! [1]