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How to “pull” data from c++ to qml?

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0

I want "pull"data from c++ in qml like this:

 Component.onCompleted: 
 MySettings.loadMainWindowPosition(aAppWnd.x, aAppWnd.y, aAppWnd.width, aAppWnd.height, aAppWnd.visibility);
 

When MySettings registered in the following way:

context->setContextProperty("MySettings", m_settings);

But when I make the funtion signature like this:

void MySettings::loadMainWindowPosition(int& x, int& y, int& width, int& height, int& visibility)

I received the following error:

qrc:/GUI/App.qml:35: Error: Unknown method parameter type: int&

So how correctly "pull" data inside qml from c++?

UPDATE:

I explain better. Now I can call the c++ function (and send params) from qml:

 Component.onCompleted: 
 MySettings.someFunc(111, 222);
 

In c++ code I receive function call with params values "111" and "222".

But I want change this parameters in c++. I want smth like that:

 Component.onCompleted: 
 var a;
 var b;
 MySettings.someFunc(a, b);
 

I want set up in the c++ code params to the "333" and "555". So after call MySettings.someFunc(a, b) I expected that (a==333) and (b==555).

How to do this?

c++ qt qml qt5 qqmlcomponent

share|improve this question

edited Mar 26 at 20:48

AeroSun

asked Mar 26 at 14:29

AeroSunAeroSun

56411 gold badge66 silver badges3030 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You cannot pass a reference, this type isn't supported in js. See here for more info. Pass an object with properties instead and so update it in QML.
  
  – folibis
  Mar 26 at 16:50
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @folibis could you please provide some example? I read your link but didnt get how to call c++ function that return values in params from qml :(
  
  – AeroSun
  Mar 26 at 20:40
  

  
  
  
  

add a comment | 

0

I want "pull"data from c++ in qml like this:

 Component.onCompleted: 
 MySettings.loadMainWindowPosition(aAppWnd.x, aAppWnd.y, aAppWnd.width, aAppWnd.height, aAppWnd.visibility);
 

When MySettings registered in the following way:

context->setContextProperty("MySettings", m_settings);

But when I make the funtion signature like this:

void MySettings::loadMainWindowPosition(int& x, int& y, int& width, int& height, int& visibility)

I received the following error:

qrc:/GUI/App.qml:35: Error: Unknown method parameter type: int&

So how correctly "pull" data inside qml from c++?

UPDATE:

I explain better. Now I can call the c++ function (and send params) from qml:

 Component.onCompleted: 
 MySettings.someFunc(111, 222);
 

In c++ code I receive function call with params values "111" and "222".

But I want change this parameters in c++. I want smth like that:

 Component.onCompleted: 
 var a;
 var b;
 MySettings.someFunc(a, b);
 

I want set up in the c++ code params to the "333" and "555". So after call MySettings.someFunc(a, b) I expected that (a==333) and (b==555).

How to do this?

c++ qt qml qt5 qqmlcomponent

share|improve this question

edited Mar 26 at 20:48

AeroSun

asked Mar 26 at 14:29

AeroSunAeroSun

56411 gold badge66 silver badges3030 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You cannot pass a reference, this type isn't supported in js. See here for more info. Pass an object with properties instead and so update it in QML.
  
  – folibis
  Mar 26 at 16:50
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @folibis could you please provide some example? I read your link but didnt get how to call c++ function that return values in params from qml :(
  
  – AeroSun
  Mar 26 at 20:40
  

  
  
  
  

add a comment | 

I want "pull"data from c++ in qml like this:

 Component.onCompleted: 
 MySettings.loadMainWindowPosition(aAppWnd.x, aAppWnd.y, aAppWnd.width, aAppWnd.height, aAppWnd.visibility);
 

When MySettings registered in the following way:

context->setContextProperty("MySettings", m_settings);

But when I make the funtion signature like this:

void MySettings::loadMainWindowPosition(int& x, int& y, int& width, int& height, int& visibility)

I received the following error:

qrc:/GUI/App.qml:35: Error: Unknown method parameter type: int&

So how correctly "pull" data inside qml from c++?

UPDATE:

I explain better. Now I can call the c++ function (and send params) from qml:

 Component.onCompleted: 
 MySettings.someFunc(111, 222);
 

In c++ code I receive function call with params values "111" and "222".

But I want change this parameters in c++. I want smth like that:

 Component.onCompleted: 
 var a;
 var b;
 MySettings.someFunc(a, b);
 

I want set up in the c++ code params to the "333" and "555". So after call MySettings.someFunc(a, b) I expected that (a==333) and (b==555).

How to do this?

c++ qt qml qt5 qqmlcomponent

share|improve this question

edited Mar 26 at 20:48

AeroSun

asked Mar 26 at 14:29

AeroSunAeroSun

56411 gold badge66 silver badges3030 bronze badges

 Component.onCompleted: 
 MySettings.loadMainWindowPosition(aAppWnd.x, aAppWnd.y, aAppWnd.width, aAppWnd.height, aAppWnd.visibility);
 

context->setContextProperty("MySettings", m_settings);

void MySettings::loadMainWindowPosition(int& x, int& y, int& width, int& height, int& visibility)

 Component.onCompleted: 
 MySettings.someFunc(111, 222);
 

 Component.onCompleted: 
 var a;
 var b;
 MySettings.someFunc(a, b);
 

share|improve this question

edited Mar 26 at 20:48

AeroSun

asked Mar 26 at 14:29

AeroSunAeroSun

56411 gold badge66 silver badges3030 bronze badges

share|improve this question

edited Mar 26 at 20:48

AeroSun

asked Mar 26 at 14:29

AeroSunAeroSun

56411 gold badge66 silver badges3030 bronze badges

asked Mar 26 at 14:29

AeroSunAeroSun

56411 gold badge66 silver badges3030 bronze badges

asked Mar 26 at 14:29

AeroSunAeroSun

56411 gold badge66 silver badges3030 bronze badges

2 Answers
2

active

oldest

votes

1

Don't try to get the return values as reference parameters when calling C++ functions from QML. Instead, use return values. To transfer more than one value in a single call, define your C++ method like

Q_INVOKABLE QVariantList someFunc() ... 

and use it in QML via

Component.onCompleted: 
 var returnValues = MySettings.someFunc();
 //access the returnValues via list indices here:
 var a = returnValues[0];
 var b = returnValues[1];

share|improve this answer

answered Mar 26 at 21:21

MitjaMitja

1,7592222 silver badges2626 bronze badges

add a comment | 

1

Passing values ​​by reference do not work calling c ++ functions from QML. If you want sync calls, use something link this in your c ++ code:

QVariantList MySettings::someFunc(int a, int b)

 QVariantList list;
 list.append(a + 5); // edit the passed values here
 list.append(b + 5); // edit the passed values here
 return list;
 

and something like this in your QML code:

var test = gapi.someFunc(3,2); // pass values here and get the new ones
console.log("The return data" + test);

share|improve this answer

answered Mar 28 at 17:50

Adriano CamposAdriano Campos

19111 silver badge66 bronze badges

add a comment | 

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1

Don't try to get the return values as reference parameters when calling C++ functions from QML. Instead, use return values. To transfer more than one value in a single call, define your C++ method like

Q_INVOKABLE QVariantList someFunc() ... 

and use it in QML via

Component.onCompleted: 
 var returnValues = MySettings.someFunc();
 //access the returnValues via list indices here:
 var a = returnValues[0];
 var b = returnValues[1];

share|improve this answer

answered Mar 26 at 21:21

MitjaMitja

1,7592222 silver badges2626 bronze badges

add a comment | 

1

Don't try to get the return values as reference parameters when calling C++ functions from QML. Instead, use return values. To transfer more than one value in a single call, define your C++ method like

Q_INVOKABLE QVariantList someFunc() ... 

and use it in QML via

Component.onCompleted: 
 var returnValues = MySettings.someFunc();
 //access the returnValues via list indices here:
 var a = returnValues[0];
 var b = returnValues[1];

share|improve this answer

answered Mar 26 at 21:21

MitjaMitja

1,7592222 silver badges2626 bronze badges

add a comment | 

Don't try to get the return values as reference parameters when calling C++ functions from QML. Instead, use return values. To transfer more than one value in a single call, define your C++ method like

Q_INVOKABLE QVariantList someFunc() ... 

and use it in QML via

Component.onCompleted: 
 var returnValues = MySettings.someFunc();
 //access the returnValues via list indices here:
 var a = returnValues[0];
 var b = returnValues[1];

share|improve this answer

answered Mar 26 at 21:21

MitjaMitja

1,7592222 silver badges2626 bronze badges

Q_INVOKABLE QVariantList someFunc() ... 

Component.onCompleted: 
 var returnValues = MySettings.someFunc();
 //access the returnValues via list indices here:
 var a = returnValues[0];
 var b = returnValues[1];

share|improve this answer

answered Mar 26 at 21:21

MitjaMitja

1,7592222 silver badges2626 bronze badges

answered Mar 26 at 21:21

MitjaMitja

1,7592222 silver badges2626 bronze badges

answered Mar 26 at 21:21

MitjaMitja

1,7592222 silver badges2626 bronze badges

1

Passing values ​​by reference do not work calling c ++ functions from QML. If you want sync calls, use something link this in your c ++ code:

QVariantList MySettings::someFunc(int a, int b)

 QVariantList list;
 list.append(a + 5); // edit the passed values here
 list.append(b + 5); // edit the passed values here
 return list;
 

and something like this in your QML code:

var test = gapi.someFunc(3,2); // pass values here and get the new ones
console.log("The return data" + test);

share|improve this answer

answered Mar 28 at 17:50

Adriano CamposAdriano Campos

19111 silver badge66 bronze badges

add a comment | 

1

Passing values ​​by reference do not work calling c ++ functions from QML. If you want sync calls, use something link this in your c ++ code:

QVariantList MySettings::someFunc(int a, int b)

 QVariantList list;
 list.append(a + 5); // edit the passed values here
 list.append(b + 5); // edit the passed values here
 return list;
 

and something like this in your QML code:

var test = gapi.someFunc(3,2); // pass values here and get the new ones
console.log("The return data" + test);

share|improve this answer

answered Mar 28 at 17:50

Adriano CamposAdriano Campos

19111 silver badge66 bronze badges

add a comment | 

Passing values ​​by reference do not work calling c ++ functions from QML. If you want sync calls, use something link this in your c ++ code:

QVariantList MySettings::someFunc(int a, int b)

 QVariantList list;
 list.append(a + 5); // edit the passed values here
 list.append(b + 5); // edit the passed values here
 return list;
 

and something like this in your QML code:

var test = gapi.someFunc(3,2); // pass values here and get the new ones
console.log("The return data" + test);

share|improve this answer

answered Mar 28 at 17:50

Adriano CamposAdriano Campos

19111 silver badge66 bronze badges

QVariantList MySettings::someFunc(int a, int b)

 QVariantList list;
 list.append(a + 5); // edit the passed values here
 list.append(b + 5); // edit the passed values here
 return list;
 

var test = gapi.someFunc(3,2); // pass values here and get the new ones
console.log("The return data" + test);

share|improve this answer

answered Mar 28 at 17:50

Adriano CamposAdriano Campos

19111 silver badge66 bronze badges

answered Mar 28 at 17:50

Adriano CamposAdriano Campos

19111 silver badge66 bronze badges

answered Mar 28 at 17:50

Adriano CamposAdriano Campos

19111 silver badge66 bronze badges