Wicket 6: Howto inject a javascript function via AbstractDefaultAjaxBehavior?

Question

I have a page that has a JavaScript file attached to it.

The JavaScript has a function that, at the end should call a function that has been injected by Wicket through AbstractDefaultAjaxBehavior.

The JavaScript looks like this:

function updateAmount(amount){
  // do some calculations on amount
  saveAmount(amount);
}

The injected function should look something like this:

function saveAmount(amount){
  Wicket.Ajax.post({
    u: '${callbackUrl}',
    dep: function(){
           return [{name:'amount','value':amount}];
         }
}

The problem I have is that when updateAmount calls the saveAmount function the (console) log states that the "saveAmount" is undefined.

If I look at the source, the injected function is there but not as JavaScript but as "AJAX" JavaScript generated by wicket.

The goal is to call a function in JavaScript that will call a function injected by Wicket that performs an AJAX call with parameters that are provided by JavaScript.

I would really appreciate any help.

Answer 1

Basically, you should use the updateAjaxAttributes() and renderHead() in a custom AbstractAjaxBehaviour

See for more detail here:

http://wickedsource.org/2013/01/07/rolling-your-own-ajax-behavior-with-wicket/

Retrieved from google cache, relevant code (written by Tom Hombergs):

public class MyAjaxBehavior extends AbstractDefaultAjaxBehavior {

@Override
protected void respond(AjaxRequestTarget target) {
RequestCycle cycle = RequestCycle.get();
WebRequest webRequest = (WebRequest) cycle.getRequest();
StringValue param1 = webRequest.getQueryParameters().getParameterValue("param1");
StringValue param2 = webRequest.getQueryParameters().getParameterValue("param2");
// do whatever you need with param1 and param2
}

@Override
public CharSequence getCallbackScript() {
String script = super.getCallbackScript().toString();
script = script.replace("\"PLACEHOLDER1\"", "param1Value");
script = script.replace("\"PLACEHOLDER2\"", "param2Value");
return script;
}

@Override
protected void updateAjaxAttributes(AjaxRequestAttributes attributes) {
super.updateAjaxAttributes(attributes);
attributes.getExtraParameters().put("param1", "PLACEHOLDER1");
attributes.getExtraParameters().put("param2", "PLACEHOLDER2");
}

@Override
public void renderHead(Component component, IHeaderResponse response) {
super.renderHead(component, response);
String script = "var param1Value = My.JavaScript.Module.calculate1();";
script += "var param2Value = My.JavaScript.Module.calculate2();";
script += getCallbackScript();
response.render(OnDomReadyHeaderItem.forScript(script));
}

}

Answer 2

I think you need to bind the content of your response to a global Javascript variable (window.MyObject.saveAmount = function(){...}).

This way you will be able to call it from your own Javascript. The problem is, in my opinion, that Wicket "sandboxes" the content of its Ajax responses to a small scope (the response one).

If my answer is invalid, please provide a more complete example.

Answer 3

private static final String MY_PARAM = "myparam";
public static class SampleCallbackBehavior extends AbstractDefaultAjaxBehavior {        
    @Override
    public void renderHead(Component component, IHeaderResponse response) {
        super.renderHead(component, response);
        response.render(OnDomReadyHeaderItem.forScript("var myfunction : " + getCallbackFunction(CallbackParameter.explicit(MY_PARAM))));
    }
    @Override
    protected void respond(AjaxRequestTarget target) {
        StringValue paramValue = getComponent().getRequest().getRequestParameters().getParameterValue(MY_PARAM);
        //TODO handle callback
    }       
}

After this, you should only call the function from javascript

myfunction("paramValue");