Question

为了扩展TreeView的节点以显示当前选择的项目（由共享选择模型设置），我需要递归调用TreeView.expand（QModelIndex）。

    expand(index)
    expand(index.parent)
    expand(index.parent.parent)
    ...

这可以通过这样的函数完成：

 function autoExpand(index ) {
    print(index)
    var oneUp = index

    do {

        print(oneUp)
        oneUp = index.parent
        expand(oneUp)
        print("do")
        print(oneUp)
    } while (oneUp)

}

但我不知道如何检查根节点。我试过了

 while (oneUp)  -> always true
 while (oneUp.isValid) -> undefined ie always false
 while (oneUp.isValid()) -> property isValid cannot be called as a function

，在c ++中它将是：

do {
   //....
} while (oneUp.isValid());

但我在QML中找不到相同的功能（并且不知道在哪里查找代码......）

作为一种解决方法，我在已经导出的对象中用c ++检查它，但是它看起来不合适：

public slots:
   bool indexIsValid(const QModelIndex &index) const {return index.isValid();}

Answer 1

作为zizix复制粘贴答案的副作用，我了解到QModelIndex :: isValid函数转换为QML中的index.valid属性（？）。使用它我现在可以在QML中成功检测到树的根：

function autoExpand(index ) {
        var oneUp = index

        do {
            oneUp = oneUp.parent
            expand(oneUp)                
        } while (oneUp.valid);

    }

Answer 2

“... \ Qt的\ 5.5 \ SRC \ qtquickcontrols \ SRC \控制\ TreeView.qml”

private void callWebservice() {

String tag_json_obj = "GetItem";
String url = String.format("http://digitalbox.getsandbox.com/item");
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
    @Override
    public void onResponse(JSONObject response) {
        try {
            saveSections(response.getJSONArray("Sections"));
// SELECT * FROM Sections where Fk == 0;
sectionsList = new RushSearch().whereEqual("Fk", 0).find(Sections.class);
Log.d("ELEMENTI",""+sectionsList.size());
drawerListViewAdapter = new DrawerListViewAdapter(sectionsList, getApplicationContext());

// Adapter che si occupa di popolare il drawer
drawerListView.setAdapter(drawerListViewAdapter);
        } catch (JSONException e) {
            e.printStackTrace();
        }

    }
}, new Response.ErrorListener() {
    public void onErrorResponse(VolleyError error) {
        VolleyLog.d("Settings", "Error: " + error.getMessage());
    }
}) {
    @Override
    public Map<String, String> getHeaders() throws AuthFailureError {
        HashMap<String, String> headers = new HashMap<String, String>();
        headers.put("Content-Type", "application/json");
        headers.put("Accept", "application/json");
        return headers;
    }
};
NetworkController.getInstance().addToRequestQueue(jsonObjectRequest, tag_json_obj);

在QML中遍历树，检查QModelIndex是否为VALal

2 个答案: