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RAP client error when disposing controls very early [message #1856531]

Wed, 14 December 2022 10:10

John Gymer

Messages: 279
Registered: November 2012
Location: UK

Senior Member

We have seen some examples where a UI is created using RAP, but something in the user's business logic results in the UI being disposed immediately (perhaps a security flag for example, where the application detects that the user should not be in that screen).

Where the dispose of the freshly-created UI happens very soon after creation, there is a potential timing issue where some UI elements have not yet been synchronised between JS on the browser and the RAP Java side on the appserver.

This can result in messages like this on the browser:

Client Error
Details
Error: Error: Operation "call" on target "rwt.client.JavaScriptExecutor" of type "[object Object]" failed:
Cannot read properties of undefined (reading '$input')
Properties: 
content = rap.getObject( 'w681' ).$input.attr( 'genname', 'PR_ERRMSG' );


  Script: {"head":{},"operations":[["set","w28",{"bounds":[0,0,0,0]}],["set","w31",{...
  Stack: Error: Operation "call" on target "rwt.client.JavaScriptExecutor" of type "[object Object]" failed:
Cannot read properties of undefined (reading '$input')
Properties: 
content = rap.getObject( 'w681' ).$input.attr( 'genname', 'PR_ERRMSG' );

    at Object._processError (http://127.0.0.1:9090/rwt-resources/3220/rap-client.js:226:3813)
    at Object.processOperationArray (http://127.0.0.1:9090/rwt-resources/3220/rap-client.js:226:924)
    at Object.processMessage (http://127.0.0.1:9090/rwt-resources/3220/rap-client.js:226:253)
    at Object._handleSuccess (http://127.0.0.1:9090/rwt-resources/3220/rap-client.js:230:3804)
    at rwt.remote.Request._success (http://127.0.0.1:9090/rwt-resources/3220/rap-client.js:98:784)
    at http://127.0.0.1:9090/rwt-resources/3220/rap-client.js:98:1875
  Debug: off
  Request: {"head":{"requestCounter":14},"operations":[["set","w27",{"activeControl":"w384"}],[...

This happens where widgets have JavaScriptExecutor performed on them for custom attributes, such as:

rap.getObject( 'w27' ).$input.attr( 'genname', 'PR_ERRMSG' );
rap.getObject( 'w27' ).$input.attr( 'spellcheck', 'true' );
rap.getObject( 'w26' ).$el.css( 'overflow', null );

...the above JS being run through this:

    JavaScriptExecutor executor = RWT.getClient().getService( JavaScriptExecutor.class );
    executor.execute( builder.toString() );

If we never use JavaScriptExecutor, then the client-side crash does not occur.

Is there a way to get the RAP client to recognise that the widget has already been destroyed and ignore the request instead of crashing?

To add, I've tried this with RAP 3.22, but looks like it applies to all versions.

---
Just because you can doesn't mean you should

[Updated on: Wed, 14 December 2022 10:12]

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Re: RAP client error when disposing controls very early [message #1856534 is a reply to message #1856531]

Wed, 14 December 2022 10:42

Ivan Furnadjiev

Messages: 2426
Registered: July 2009
Location: Sofia, Bulgaria

Senior Member

Hi John,

the crash didn't come from the RAP framework code, but from your custom JavaScript code that is executed with JavaScriptExecuter. The fix is simple. Just update you custom JavaScript code like:

var object = rap.getObject( 'w27' );
if( object ) {
  object.$input.attr( 'genname', 'PR_ERRMSG' );
  object.$input.attr( 'spellcheck', 'true' );
  ...
}

Best regards,
Ivan

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