issue converting proxied v8 java array to java object

[narsinallamilli]

Proxied Java V8 object is manipulated in javascript to set array field but it doesn't set. However List works.

`
public class Apple {
private String[] appleColors;

public String[] getAppleColors() {
    return appleColors;
}

public void setAppleColors(String[] appleColors) {
    this.appleColors = appleColors;
}

}

//kotlin test
@test
fun testSamp() {
try {
val javetV8Engine = javetEngineV8Pool.getEngine()
val javetV8Runtime = javetV8Engine.v8Runtime
val javetBridgeConverter = JavetBridgeConverter()
javetBridgeConverter.config.setReflectionObjectFactory(JavetReflectionObjectFactory.instance);
javetV8Runtime.setConverter(javetBridgeConverter)
val apple = Apple()
javetV8Runtime.globalObject.set("apple", apple);
javetV8Runtime.getExecutor("""
apple.appleColors = ['a']
""".trimIndent()).executeVoid();
println(apple.appleColors)
javetV8Runtime.lowMemoryNotification()
} catch (javetException: JavetException) {
println(javetException)
}
}
Above test outputs
null
if the appleColors is changed to List<String> the output is
[a]
`

[caoccao]

This is the expected behavior: Native JS array is always converted to List<Object>.

[narsinallamilli]

@caoccao the object classes are of third party libs, so there is no way I can change from Array to List, isn't there any workaround?
Do you mean List is set to Object[] type?

[caoccao]

I think you may inject a JS function as follows.

1. Write a Java method (e.g. list2Array) that converts List<Object> to Object[].
2. Inject that Java method as a JS function list2Array.
3. Call external.acceptObjectArray(list2Array(nativeJSArray)).

[caoccao]

That might be possible, and indirect. I'll investigate that later. Please stay in tune.

[narsinallamilli]

Thank you, I guess this should be handled by JavetProxyPluginArray.

[caoccao]

Please check commit 1 and commit 2 out. By calling Object.seal(), JS array will be converted to Object[] instead of List<Object>. It's disabled by default, but can be turned on. This feature will be included in the next release. Please let me know if you have any questions. By the way, thank you for the donation!

v8Runtime.getConverter().getConfig().setSealedEnabled(true);
assertArrayEquals(
        new Object[]{1, 2},
        v8Runtime.getExecutor("Object.seal([1,2])").executeObject());
assertArrayEquals(
        new Object[]{"a", "b"},
        v8Runtime.getExecutor("Object.seal(['a','b'])").executeObject());
assertArrayEquals(
        new Object[]{},
        v8Runtime.getExecutor("Object.seal([])").executeObject());

[narsinallamilli]

@caoccao

I tested out this feature, however I see the the java array field is not set.

public class Apple {
    private String[] appleColors;


    public String[] getAppleColors() {
        return appleColors;
    }

    public void setAppleColors(String[] appleColors) {
        this.appleColors = appleColors;
    }
}

@Test
    fun testSamp() = try {
        val javetV8Engine = javetEngineV8Pool.getEngine()
        val javetV8Runtime = javetV8Engine.v8Runtime
        val javetBridgeConverter = JavetBridgeConverter()
        javetBridgeConverter.config.setReflectionObjectFactory(JavetReflectionObjectFactory.instance);
        javetBridgeConverter.config.setSealedEnabled(true)
        javetV8Runtime.converter = javetBridgeConverter
        val apple = Apple()
        javetV8Runtime.globalObject.set("apple", apple);
        javetV8Runtime.getExecutor("""
            apple.appleColors = Object.seal(['narsi'])
        """.trimIndent()).executeVoid()
        println(apple.appleColors)
        javetV8Runtime.lowMemoryNotification()

    } catch (javetException: JavetException) {
        println(javetException)

    }

output is
null

However if I change appleColors type to Object[] its works.

[caoccao]

That is unfortunate. It's hard to cast Object[] to any other types of array, because:

1. The converter doesn't know the target type.
2. Even if the target type is known, the converter has to go over every element to validate the type. That's O(N) and impacts the performance considerably.

In this case, I suggest you implement your own proxy plugin. Please let me know if you have any questions.