QtQuick - qml:28:错误:未知方法返回类型:自定义类型

QtQuick - qml:28: Error: Unknown method return type: custom type

本文关键字：返回类型 方法 自定义 类型 未知 错误 qml QtQuick      更新时间：2023-10-16

我想做什么

我有两个班级ObjectA和ObjectB。ObjectA是ObjectB的组成。 我想创建一个按钮，用于调用 QML 中ObjectBinsert(int num, ObjectA &A)函数。

我的代码：

对象a.h 

//...
#include <QObject>
#include <QDateTime>
class ObjectA
{
public:
explicit ObjectA(QString str);
//...    
private:
//...
};
//...

objectb.h

//... 
#include <QObject>
#include <QList>
#include <QDebug>
#include "objecta.h"

class ObjectB : public QObject
{
Q_OBJECT
public slots:
ObjectA generate(QString str);
void insert(int priority, ObjectA &A);
public:
ObjectB(QObject *parent = nullptr);
//...
private:
//...
};
//...

对象.cpp

include "objecta.h"
ObjectA::ObjectA(QString str)
{
//...
}

对象B.cpp

include "objectb.h"
//Object A is a composition of Object B
ObjectA ObjectB::generate(QString str){
ObjectA *A = new ObjectA(str);
return *A;
}
// ^ I will use the *A as the parameter for the &A in function insert()
void ObjectB::insert(int num, ObjectA &A){ 
//...
}
//...

主.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "objectb.h"
int main(int argc, char *argv[])
{
ObjectB B;
qmlRegisterType<ObjectB>("com.mycompany.ObjectB", 1, 0, "ObjectB");
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
const QUrl url(QStringLiteral("qrc:/main.qml"));
QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
&app, [url](QObject *obj, const QUrl &objUrl) {
if (!obj && url == objUrl)
QCoreApplication::exit(-1);
}, Qt::QueuedConnection);
engine.load(url);
return app.exec();
}

主.qml

import QtQuick 2.12
import QtQuick.Window 2.12
import com.mycompany.ObjectB 1.0
Window {
//...
ObjectB {
id: objectb
}
Page {} //Page.qml
}

Page.qml

import QtQuick 2.0
import QtQuick.Controls 2.1
Row {
id: row
anchors.centerIn: parent
spacing: 20
TextField {
id: strfield
}
ComboBox {
id: numbox
width: 200
model: [ "1", "2", "3" ]
}
Button {
id: btninsert
text: "Insert"
highlighted: true
onClicked: objectb.insert(numbox.currentIndex+1,objectb.generate(strfield.text))
}
}

我得到的错误

当我单击按钮时，我收到此错误消息：

qrc:/Page.qml:28: Error: Unknown method return type: ObjectA

我认为问题出在objectb.generate(strfield.text)由于QML无法识别自定义类型而无法返回ObjectA。我该如何解决？

编辑：添加了ObjectA和ObjectB的头文件，以及ObjectA的cpp文件

临时解决方案：

避免在 QML 中使用自定义返回类型。

objectb.h 

//... 
#include <QObject>
#include <QList>
#include <QDebug>
#include "objecta.h"

class ObjectB : public QObject
{
Q_OBJECT
public slots:
// A new function that combine both generate and insert function
void btnInsert(int priority, QString str)
ObjectA generate(QString str);
void insert(int priority, ObjectA &A);
public:
ObjectB(QObject *parent = nullptr);
//...
private:
//...
};
//...

对象B.cpp

include "objectb.h"
//Implement new function
void ObjectB::btnInsert(int priority, QString str)
{
ObjectA *A = new ObjectA(str);
//Code implementation...
}
//Object A is a composition of Object B
ObjectA ObjectB::generate(QString str){
ObjectA *A = new ObjectA(str);
return *A;
}
// ^ I will use the *A as the parameter for the &A in function insert()
void ObjectB::insert(int num, ObjectA &A){ 
//...
}
//...

请注意Button中的onClicked。

Page.qml

import QtQuick 2.0
import QtQuick.Controls 2.1
Row {
id: row
anchors.centerIn: parent
spacing: 20
TextField {
id: strfield
}
ComboBox {
id: numbox
width: 200
model: [ "1", "2", "3" ]
}
Button {
id: btninsert
text: "Insert"
highlighted: true
//Modified
onClicked: objectb.insert(numbox.currentIndex+1,strfield.text)
}
}
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