POST redirect from managed bean - jsf

Question

I have a simple JSF and managed bean and I need to make POST redirect when page render and some condition is true. JSF:
<h:panelGroup rendered="#{myBean.error=null}">
<p>Some data</p>
</h:panelGroup>
In managed bean, the init() method, annotated as #PostConstruct and in this method I do
#PostConstruct
public void init() {
if (someCondition) {
FacesContext context = FacesContext.getCurrentInstance();
String redirectUrl = "http://myurl.com";
ExternalContext ec = FacesContext.getCurrentInstance().getExternalContext();
try {
ec.redirect(redirectUrl);
} catch (IOException e) {
e.printStackTrace();
FacesMessage message = new FacesMessage(e.getMessage());
context.addMessage(null, message);
}
}
}
but I need navigate user to redirectUrl with POST params and cannot find how to do it.
With button it will be like this:
<form method='post' action="myUrl">
<input type='hidden' name='param1' value='value1'/>
<input type='hidden' name='param2' value='value2'/>
<input name='button' type='submit' value="Button">
</form>

Answer 1

What you try to achieve is not possible that way.
A redirect will send a http 302 status code to the client with a location header including an url where to redirect to. Then the client will make a get request to that url and your post data will be lost.
There are alternatives to achieve this, here are some ideas.
You could forward the request using the ExternalContext.html#dispatch method, see this post for the differences. Note that this does not change the url in the browser's address bar.
You could store the post data in the user's session.