Add widget to pure html that is not part of DOM-structure yet

Question

Okay, this really gets annoying since I am sure that GWT should support what I want to do. I asked already two times and I searched the web but I just can't find a solution to my problem.

What I want to do is to load a textfile from the server that e.g. looks like this:

<!-- linear_regression.txt -->
<h1>Linear Regression</h1>
Welcome to this chapter. Here, have a graph:
<div id="whatever"></div>
Alright, now have some math stuff:

and place a Widget - in my case a line chart - into the div <div id="whatever">. I tried a few things..

---

Inside the onSuccess() method of an RPC I want to do something like that:

public void onSuccess(String result) {

    HTMLPanel tmp = new HTMLPanel(result);
    Element el = tmp.getElementById("whatever");

    el.appendChild(new LineChart().asWidget().getElement());

    contentRoot.add(tmp);
}

If I do it like that, my result looks like this:

<div id="whatever">
    <!-- Here I want the chart to be placed but all I get is this: -->
    <div></div> 
</div>

---

The other approach looks like this:

    HTMLPanel tmp = new HTMLPanel(result);
    contentHome.add(tmp);

    Element el = RootPanel.get("whatever").getElement();
    el.appendChild(new LineChart().asWidget().getElement());

But here I get an uncaught exception:

java.lang.AssertionError: A widget that has an existing parent widget 
may not be added to the detach list
    at com.google.gwt.user.client.ui.RootPanel.detachOnWindowClose(RootPanel.java:136)
    at com.google.gwt.user.client.ui.RootPanel.get(RootPanel.java:211)
    at ew.client.layout.MainLayout$1.onSuccess(MainLayout.java:95)
    at ew.client.layout.MainLayout$1.onSuccess(MainLayout.java:1)
    ...

---

I really get sick of this issue. Does anyone know how I can solve this problem?

Answer 1

Wrap the div in an HTLMPanel

LineChart lineChart = new LineChart();
HTMLPanel panel = new HTMLPanel(result);
panel.add(lineChart, "whatever");