如何从c更改qml中TableView的模型属性-Java 学习之路

我对QT比较陌生，所以任何帮助都将不胜感激！

我正在研究Qt快速应用程序，利用QQmlApplicationEngine进行用户界面 . 我创建了QAbstractTableModel的子类并实现了必要的功能，并在Window上成功创建并显示了一个（奇异的）表 .

目前，我如何在QML文件中链接模型是通过设置QQmlApplicationEngine的root属性的context属性 .

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QSharedPointer>
#include <QQmlContext>

#include "tablecontroller.h"

int main(int argc, char *argv[])
{
  QGuiApplication app(argc, argv);

  QSharedPointer<QQmlApplicationEngine> engine = 
                     QSharedPointer<QQmlApplicationEngine>::create();

  TableController theController(engine.toWeakRef());

  engine.data()->rootContext()->setContextProperty("TableController", &theController);

  engine.data()->load(QUrl(QStringLiteral("qrc:/main.qml")));
  return app.exec();
}

tabcontroller.h

#ifndef TABLECONTROLLER_H
#define TABLECONTROLLER_H

#include <QObject>
#include <QQmlApplicationEngine>
#include <QWeakPointer>
#include <QHash>
#include <QList>

#include "tablemodel.h"

class TableController : public QObject
{
  Q_OBJECT
public:
    explicit TableController(QWeakPointer<QQmlApplicationEngine> Engine, QObject *parent = 0);

    Q_INVOKABLE void AddEntry();

signals:

public slots:

private:
  TE::TDT::TableModel m_TableModel;
  QList<QString> m_Headings;
};

#endif // TABLECONTROLLER_H

tabcontroller.cpp

#include "tablecontroller.h"
#include <QQmlContext>

TableController::TableController(QWeakPointer<QQmlApplicationEngine> Engine, QObject *parent) : QObject(parent)
{
  m_Headings << "Heading1" << "Heading2" << "Heading3" << "Heading4";
  m_TableModel.setColumnHeadings(m_Headings);

  Engine.data()->rootContext()->setContextProperty("myModel", &m_TableModel);
}

void TableController::AddEntry()
{
  QHash<QString, QVariant> tempHash;
  int counter = 1;
  for (auto x : m_Headings)
  {
    tempHash.insert(x, QString::number(counter));
    counter++;
  }
  m_TableModel.addElement(tempHash);
}

tablemodel.h

#ifndef TABLEMODEL_H
#define TABLEMODEL_H

#include <QObject>
#include <QAbstractItemModel>
#include <QModelIndex>
#include <QVariant>
#include <QList>
#include <QString>
#include <QHash>

namespace TE {

namespace TDT {

class TableModel : public QAbstractTableModel
{
  Q_OBJECT
  Q_PROPERTY(QStringList userRoleNames READ userRoleNames CONSTANT)
public:
    explicit TableModel(QObject *parent = 0);

    enum MyModelRoles {
        UserRole1 = Qt::UserRole + 1,
        UserRole2,
    };

  void setFirstColumn(const QList<QString> &FirstColumn);

  void setColumnHeadings(const QList<QString> &ColumnHeadings);

  void addElement(const QHash<QString, QVariant> Entry);

  QStringList userRoleNames();

signals:

public slots:

// QAbstractTableModel interface
public:
  int rowCount(const QModelIndex &parent) const override;
  int columnCount(const QModelIndex &parent) const override;
  QVariant data(const QModelIndex &index, int role) const override;
  QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
  QHash<int, QByteArray> roleNames() const override;

private:
  QList<QHash<QString, QVariant>> m_TableData;
  QList<QString> m_ColumnHeadings;
  QMap<int, QString> m_roleNames;

};

}// TDT

}// TE

#endif // TABLEMODEL_H

tablemodel.cpp

#include "tablemodel.h"
#include <QDebug>
#include <QAbstractListModel>

TE::TDT::TableModel::TableModel(QObject *parent) : QAbstractTableModel(parent)
{

}

int TE::TDT::TableModel::rowCount(const QModelIndex &parent) const
{
  Q_UNUSED(parent);
  return m_TableData.count();
}

int TE::TDT::TableModel::columnCount(const QModelIndex &parent) const
{
  Q_UNUSED(parent);
  return m_ColumnHeadings.count();
}

QVariant TE::TDT::TableModel::data(const QModelIndex &index, int role) const
{
  QVariant retVal;
  try {
     if(!index.isValid())
     {
         throw QString("Invalid index for inherited data function");
     }
     // Check row index
     if(index.row() >= m_TableData.count() || index.row() < 0)
     {
         throw QString("Index (row) out of bounds for data function");
     }
     //Check column index
     if(index.column() >= m_ColumnHeadings.count() || index.column() < 0)
     {
         throw QString("Index (column) out of bounds for data function");
     }

     QList<int> keys = m_roleNames.keys();

     if(role == Qt::DisplayRole || role == Qt::EditRole)
     {
         QString colKey = m_ColumnHeadings.at(index.column());
         if (m_TableData.at(index.row()).value(colKey).isNull())
         {
             retVal = QVariant();
         } else {
             retVal = m_TableData.at(index.row()).value(colKey);
         }
     } else if (m_roleNames.keys().contains(role)) {
         QHash<QString, QVariant> temp1 = m_TableData.at(index.row());
         retVal = m_TableData.at(index.row()).value(m_roleNames.value(role));
     }
     return retVal;

  } catch (QString &e) {
     qDebug() << e;
     return QVariant();
  }
}

QVariant TE::TDT::TableModel::headerData(int section, Qt::Orientation orientation, int role) const
{
  Q_UNUSED(orientation);
  QVariant retVal;
  if (role == Qt::DisplayRole)
  {
     retVal = m_ColumnHeadings.at(section);
  }
  return retVal;
}

QHash<int, QByteArray> TE::TDT::TableModel::roleNames() const {
  // Populate the roles - basically the column headings
  QHash<int, QByteArray> roles = QAbstractTableModel::roleNames();

  // Should not overwrite existing roles
  int LastIndexOfUserRole = Qt::UserRole;
  for (int x = 1; x <= m_ColumnHeadings.count(); x++)
  {
     roles[LastIndexOfUserRole + x] = m_ColumnHeadings.at(x-1).toUtf8();
  }
  return roles;
}

QStringList TE::TDT::TableModel::userRoleNames() // Return ordered List of user-defined roles
{
  QHashIterator<int, QByteArray> i(roleNames());
  while (i.hasNext())
  {
     i.next();
     if(i.key() > Qt::UserRole)
     {
         m_roleNames[i.key()] = i.value();
     }
  }
  return m_roleNames.values();
}

void TE::TDT::TableModel::setColumnHeadings(const QList<QString> &ColumnHeadings)
{
  m_ColumnHeadings = ColumnHeadings;
}

void TE::TDT::TableModel::addElement(const QHash<QString, QVariant> Entry)
{
   beginInsertRows(QModelIndex(), this->rowCount(QModelIndex()), this->rowCount(QModelIndex()));
   m_TableData.append(Entry);
   endInsertRows();
}

main.qml import QtQuick 2.5导入QtQuick.Window 2.2导入QtQuick.Controls 1.2

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    id: mainwindow

    // template component for the column headings
    Component
    {
        id: columnComponent
        TableViewColumn{width: 100 }
    }

    TableView {
        id: tableview
        height: mainwindow.height - 50
        width: mainwindow.width
        y: 5
        x: 0
        visible: true
        resources:
        {
            var roleList = myModel.userRoleNames
            var temp = []
            for(var i = 0; i < roleList.length; i++)
            {
                var role  = roleList[i]
                temp.push(columnComponent.createObject(tableview, { "role": role, "title": role}))
            }
            return temp
        }
        model: myModel
    }

    Rectangle {
        id: abutton
        anchors.top: tableview.bottom
        height: 40
        width: mainwindow.width

        Text {
            text: "Click to Add"
            anchors.fill: parent
        }

        MouseArea {
            anchors.fill: parent
            onClicked: {
                TableController.AddEntry()
            }
        }
    }
}

代码改编自：QML TableView with dynamic number of columns

现在，我的问题是，如果我想重新使用_1186024中定义的TableView，我想使用另一个模型 . 问题是（根据我的有限理解），QML中的模型链接到的"variable"是静态的（在启动时定义），在本例中为"myModel" .

一旦我创建了此TableView的另一个实例，我该如何更改模型？我每次都要连接另一个"variable"吗？

我试图将TableView（在QML中）转换为QQuickItem（在c中）并尝试在那里设置属性，无效（给出null，但QQuickItem也没有“setModel”函数）

对不起，很长的帖子，想尽可能多地提供信息 .

3 回答

0

正如@folibis所说，一个选项是使您的模型可以从QML实例化，即，这样您就可以在QML中使用该模型的实例 .

然后，您可以在控制器需要知道它们的情况下将方法添加到 TableController 到"register"这些实例 .

或者，您仍然可以在 TableController 内创建模型并使其可访问，例如通过每个模型的一个属性，列表属性或 Q_INVOKABLE 方法 .

回复于 2024-04-20T02:58:55+08:00

如果我正确理解您的问题，您需要将自定义 TableView 重用于其他模型，您实际上不需要更改现有 TableView 的 model .

为此，您可以在单独的文件中定义一个新组件并在其他地方使用它（这里的一些文档：http://doc.qt.io/qt-5/qtqml-documents-definetypes.html）

在你的情况下，它可能看起来像这样：

DynamicTableView.qml ：

TableView {
    //it's better not to set positioning properties in a component definition file.
    Component {
        id: columnComponent
        TableViewColumn { width: 100 }
    }  
    resources:
    {
        var roleList = model.userRoleNames // here you expect all your models to be an instance of your TableModel
        var temp = []
        for(var i = 0; i < roleList.length; i++)
        {
            var role  = roleList[i]
            temp.push(columnComponent.createObject(tableview, { "role": role, "title": role}))
        }
        return temp
    }
}

然后，您可以在 main.qml 中重用您的组件并定义其 model 属性：

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    id: mainwindow    

    DynamicTableView {
        id: tableview
        height: mainwindow.height - 50
        width: mainwindow.width
        y: 5
        x: 0
        model: myModel
    }    

    Rectangle {
        id: abutton
        anchors.top: tableview.bottom
        height: 40
        width: mainwindow.width    

        Text {
            text: "Click to Add"
            anchors.fill: parent
        }    

        MouseArea {
            anchors.fill: parent
            onClicked: {
                TableController.AddEntry()
            }
        }
    }
}

回复于 2024-04-20T02:58:55+08:00

0

https://stackoverflow.com/a/35755172/7094339

这家伙救了我的命：D所以看来我需要使用component.beginCreate（）函数 .

回复于 2024-04-20T02:58:55+08:00

如何从c更改qml中TableView的模型属性

3 回答

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