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struts2 + json plugin problems

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posted 14 years ago

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I'm using the json plugin that comes with struts 2 (json-lib-2.1.jar) and trying to follow the website to set it up.

Here's my struts.xml

but I get this warning:
SEVERE: Unable to find parent packages json-default

Is there something else I'm supposed to do?

David Newton

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posted 14 years ago

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What else have you done besides use the "extends" attribute? The json plugin isn't called "json-lib-2.1.jar"; that's just the JSON part--are you deploying the actual plugin?

Pj Casaro

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posted 14 years ago

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I actually didn't have the correct plugin! Ok, so I put in the right plugin, but still some problems.

However, I don't think the response is going from the RetrieveUser class to the javascript. I'm using firebug and no request gets sent.

David Newton

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posted 14 years ago

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Without knowing how you're making the request, it's impossible to help diagnose why it's not happening.

Pj Casaro

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posted 14 years ago

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Yes I understand, sorry I'm new to this so not too sure what things are relevant.

Here's everything I have.

1) The user clicks a link which triggers this action:

2) This just populates a list of users, and then automatically returns this result:

3) Here's my RetrieveUser class:

4) And my javascript file:

/*
 * Much of this Javascript is borrowed from the early chapters of another Manning title,
 * Ajax in Action.  Thanks to the authors of that book ( Dave Crane, Eric Pascarello, Darren James )
 * for letting us borrow some Ajax connectivity code.  
 */

var req=null;
var console=null;
var READY_STATE_UNINITIALIZED=0;
var READY_STATE_LOADING=1;
var READY_STATE_LOADED=2;
var READY_STATE_INTERACTIVE=3;
var READY_STATE_COMPLETE=4;

function onReadyState() {
	var ready=req.readyState;
	var jsonObject=null;
	
	if ( ready == READY_STATE_COMPLETE ){
			jsonObject=eval( "("+ req.responseText +")" );
		  toFinalConsole ( jsonObject );
	}
}

function removeAllChildren( node ){
	var childCount = node.childNodes.length;
	for ( var count = 1; count <= childCount; count++) {
		node.removeChild ( node.childNodes[0] );
	}
}

function fetchUser()
{
  console=document.getElementById('console');
  var selectBox = document.getElementById('AjaxRetrieveUser_username');
  var selectedIndex = selectBox.selectedIndex;
  var selectedValue = selectBox.options[selectedIndex].value
  sendRequest("AjaxRetrieveUser.action", "username=" + selectedValue , "POST");
}

5) And finally my struts.xml:

In firebug, I can see that when I change an item in the select menu (triggering the onchange=fetchUser) I get this error in the javascript here:
that says "setting a property that has only a getter". I don't think the javascript is the problem because I've gotten this javascript to work before just not with this json plugin.

Pj Casaro

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posted 14 years ago

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Ok I found two problems.

The first is that I can't use the variable name "console" in my javascript when I'm using firebug I think. So I changed that.

The second is, now that I have a json result (finally!), I can't figure out how to parse it correctly.

Here's what it looks like (part of it):

The json is stored under jsonObject so I'm trying to access the user by saying "jsonObject.jsonModel[0]" but that's undefined. The problem is, it serialized the whole thing as an object and I don't know what "myusername" is going to be, so I can't just say jsonModel.myusername.

David Newton

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posted 14 years ago

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You're getting an error in JavaScript but don't think it's in the JavaScript?

I'm pretty sure it is, *if* you're actually getting an error in the JavaScript. That's some pretty old-school JavaScript, too--yuck.

In any case, I don't understand why that would be an error you'd get in JavaScript itself, since JavaScript has no concept of getters and setters, but if it's a JavaScript error, it's most assuredly an error in JavaScript or the DOM with which it is interacting.

Pj Casaro

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posted 14 years ago

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The code is from Struts 2 in action, a book I've been going through to try and learn struts.

David Newton

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posted 14 years ago

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Pj Casaro wrote:The json is stored under jsonObject so I'm trying to access the user by saying "jsonObject.jsonModel[0]" but that's undefined. The problem is, it serialized the whole thing as an object and I don't know what "myusername" is going to be, so I can't just say jsonModel.myusername.

Then it's probably not reasonable to serialize it like that, or you'll have to iterate over the properties to find out what the user name actually is.

Pj Casaro

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I figured as much and went ahead and changed it to serialize over my "User" object instead of the whole class. Now it almost works. However I do have maps as part of the user and the maps get converted to maps again in json, so I do have to iterate over keys at some point anyway. Is there a numkeys/size/length command for the number of keys in something?

David Newton

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posted 14 years ago