Thursday, January 24, 2019

Re: Error When Calling java method via JSNI - Cannot read property 'apply' of undefined

I found the issue in my code.  The specific issue was how the parameters were defined in "handleJobDefinition".  It's basically a JSNI syntax error.  
$wnd.displayJobDefinitionDialog = $entry(@com.function.operation.Class::handleJobDefinition(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)(jobId, jobType, serviceId));

--should be defined as --

$wnd.displayJobDefinitionDialog = $entry(@com.function.operation.Class::handleJobDefinition(III);

This JSNI reference was extremely helpful:

On Wednesday, January 23, 2019 at 11:56:30 AM UTC-6, Thomas Broyer wrote:

On Tuesday, January 22, 2019 at 11:47:18 PM UTC+1, Jeff Ledgerwood wrote:
GWT 2.8.0

I am pulling my hair out with this error.  Hoping someone can help.  I am calling a Java method (in a GWT class) from an external javascript file.  I've done this without issue with several other java calls.  However, when I make the call from javascript to GWT and try to pass any parameters from javascript to the GWT method via JSNI, I get a cryptic error that I am unable to trace.

Javascript function  (used this same pattern on multiple occasions without issue)
function openJobDetailsDialog(){
this.displayJobDefinitionDialog("1", "2", "3");

GWT methods:

public native void displayJobDefinitionDialog(String jobId, String jobType, String serviceId) /*-{
$wnd.displayJobDefinitionDialog = $entry(@com.function.operation.Class::handleJobDefinition(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)(jobId, jobType, serviceId));

This code calls handleJobDefinition and passes its returned value (which is 'undefined', given that the method's return type is 'void') to $entry(), which wraps it into a function.
So $wnd.displayJobDefinitionDialog is a function, but calling it will fail when $entry() will try to invoke the "wrapped" function (which is 'undefined').

I must say I don't understand your code: where are you expecting the 3 arguments to come from? Java or JS?

If they're supposed to come from Java, and JS would call the method with zero argument, then use:
$wnd.displayJobDefinitionDialog = $entry(function() { @Class:handleJobDefinition(*)(jobId, jobType, serviceId); });

and call it with

otherwise, use:
$wnd.displayJobDefinitionDialog = $entry(@Class:handleJobDefinition(*));
$wnd.displayJobDefinitionDialog = $entry(function(a, b, c) { @Class:handleJobDefinition(*)(a, b, c) });

and call it as
window.displayJobDefinitionDialog("1", "2", "3");

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