Json parse error - Web user control

I'm learning to use web user controls because we're planning on use a javascript gantt diagram in CSI. I can't find documentation about the js assets so I'm analyzing what's done in another user controls like Engineering Board and MGMapper, but I'm having some issues.

What I understand is that you send data to the js vía a function called MG.UserControl.registerListener. I'm sending a JSON object with a form event handler:

COMPONENT(userControl1) PARMS({ "Action": "addProj", "Name": "P(ProjDesc)"})

And this is my js:

Of course I'm linking UserControl.js in my html file.

So when I debug with my browser I get this weird error:

Seems like e.Data is empty. I don't know where I can send that initial data. Debugging EngineeringBoard shows there's a string there but I don't find where its send. At least not in the form script, nor another js or a form event.

How can I send that data?

Thanks

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Legacy Contributor

Hi,

Of what I see inside your code, it looks almost the same as what we do.

So first, I would not try to parse the JSON message but just send back the content of the JSON to a variable and see if it is correct.

Then Check why this can't be parsed by the JSON.parse function.

But your UserControl thing and your event handler looks good to me (beside the fact that perhaps ' " ' are not welcomed but it shouldn't).

Just try step by step debugging. You should be able to read the JSON correctly.

Thank you

avillanueva

The thing is, that Json.parse runs when the form loads, and I don't know where it takes the json from. For example, this is what's parsed when Engineering Board loads:

And this when my form loads.

I just don't know when or where that JSON is sent to UserControl.js

0911060553270289.pdf

Legacy Contributor

I think they are some default events which are triggered for example when the form is loaded, it loads the web user control, so it triggers the handleResponse function even if the msg isn't a JSON.

Currently, your function named handleResponse is triggered everytime an event occured on the web user control.

It must have some that you don't necerally want to catch so what we have done inside this function is something like this:

FormAction: function (msg) { // same as your handleResponse()
var action = msg.substring(0,msg.indexOf(":"));
var payLoad = msg.substring(msg.indexOf(":") + 1);
if ( action == "ACTION1") {
somethingToDo(payLoad);
} else if (action == "ACTION2")
{ // do something else
}

}

And inside the form, send your event handler like this:

COMPONENT(userControl1) PARMS(ACTION1:<JSON>...</JSON>)

So if the msg received isn't starting by ACTION1 or ACTION2, then it does not try to parse it as a JSON.

avillanueva

I tried to use that in my MG.onReady but i got the same error. Is there a form event that can send the initial data to the js?

Or maybe is it managed by the assembly? Do you have an example? I can't find the EngineeringBoard.dll in the Syteline folder.

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