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Thread: QtScript: accessing methods of QObject* subclass from script

  1. #1
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    Default QtScript: accessing methods of QObject* subclass from script

    I am very new to QtScript and I have used QScriptEngine::evaluate() to evaluate this script:

    Qt Code:
    1. function render(node) {
    2. var stream = node.getStream();
    3. print("typeof stream "+typeof stream + "," + stream);
    4. var test = stream.test();
    5. }
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    Now, I have used Q_DECLARE_METATYPE(Stream*)
    and node.getStream() returns Stream*

    In the script the output is as follows:

    Qt Code:
    1. typeof stream object,QVariant(Stream*)
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    Stream has a public slot with testmethod() returning an int:

    Qt Code:
    1. public slots:
    2. int testmethod() {return 8;}
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    But then I get the following TypeError in the script when I try to access the testmethod() method of Stream

    TypeError: Result of expression 'stream.testmethod' [undefined] is not a function.

    I am obviously not doing this right? Can someone help me in the right direction to make this work?

    Many thanks.

  2. #2
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Bump, same problem.

  3. #3
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    The object needs to be exposed as QObject and not QVariant.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  4. #4
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Ok, mine is not exactly the same problem.

    I had exposed a instance of a class that inherits QObject, ClsUserManager:

    Qt Code:
    1. engine.globalObject().setProperty("UserManager",engine.newQObject(UserManager));
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    UserManager has this public slot:
    Qt Code:
    1. OtherCustomClass* getUser(QString id);
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    OtherCustomClass has a slot:
    Qt Code:
    1. void setProperty(QString p)
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    I tried to call de slot from my script:
    Qt Code:
    1. UserManager.getUser(id).setProperty(p);
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    I get:
    Qt Code:
    1. Debug: "TypeError: cannot call getUser(): unknown return type `OtherCustomClass*' (register the type with qScriptRegisterMetaType())"
    To copy to clipboard, switch view to plain text mode 

    The problem is that I can't call qScriptRegisterMetaType() from OtherCustomClass, it gets "QScriptEngine * engine" as first param, and I created some instances of QScriptEngine (by demmand) dinamically.

    Regards

  5. #5
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Does "OtherCustomClass" inherit QObject?
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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  6. #6
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Yes, all classes I use in the project inherit QObject.

  7. #7
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Does it have a Q_OBJECT macro?
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  8. #8
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Yes, I can call their slots from C++ code without any problem. I could try to reproduce it on a minimal compilable project if you need it.

  9. #9
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Ok, got it...

    The problem is that you need to teach your script engine to convert your objects to script values.

    Here is the relevant code:

    Qt Code:
    1. Q_DECLARE_METATYPE(OtherCustomClass*)
    2.  
    3. QScriptValue toScriptValue(QScriptEngine *e, OtherCustomClass* const &o) {
    4. return e->newQObject(o);
    5. }
    6.  
    7. void fromScriptValue(const QScriptValue &val, OtherCustomClass* &o) {
    8. o = qobject_cast<OtherCustomClass*>(val.toQObject());
    9. }
    10.  
    11. qScriptRegisterMetaType<OtherCustomClass*>(engine, fromScriptValue, toScriptValue);
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    Or more general:

    Qt Code:
    1. template <typename Tp>
    2. QScriptValue qScriptValueFromQObject(QScriptEngine *engine, Tp const
    3. &qobject)
    4. {
    5. return engine->newQObject(qobject);
    6. }
    7.  
    8. template <typename Tp>
    9. void qScriptValueToQObject(const QScriptValue &value, Tp &qobject)
    10. {
    11. qobject = qobject_cast<Tp>(value.toQObject());
    12. }
    13.  
    14. template <typename Tp>
    15. int qScriptRegisterQObjectMetaType(
    16. QScriptEngine *engine,
    17. const QScriptValue &prototype = QScriptValue()
    18. #ifndef qdoc
    19. , Tp * /* dummy */ = 0
    20. #endif
    21. )
    22. {
    23. return qScriptRegisterMetaType<Tp>(engine, qScriptValueFromQObject, qScriptValueToQObject, prototype);
    24. }
    25.  
    26. qScriptRegisterQObjectMetaType<OtherCustomClass*>(engine);
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    The last snippet is not my invention, borrowed it from here: http://lists.trolltech.com/qt-intere...ad00158-0.html
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  10. The following user says thank you to wysota for this useful post:

    [Zero] (5th July 2012)

  11. #10
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    Default Re: QtScript: accessing methods of QObject* subclass from script

    Solved, Thank you very much!

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