QML与C++交互:在qml中使用QSqlQueryModel显示数据库数据

QML与C++交互:在qml中使用QSqlQueryModel显示数据库数据

本文博客链接:http://blog.csdn.net/jdh99,作者:jdh,转载请注明.

參考链接:

http://qt-project.org/wiki/How_to_use_a_QSqlQueryModel_in_QML

环境：

主机:WIN7

开发环境:Qt5.2.1

说明:

在QML中不能直接对数据库进行操作,所以将QSqlQueryModel封装成子类,作为属性给QML使用

效果图:

源码:

qml文件里负责数据托管显示的代码:

Component
        {
            id: msnDelegate
            Item
            {
                id: wrapper
                width: grid.cellWidth; height: grid.cellHeight
                Column
                {
                    Image{ source: "pics/light_on.png";anchors.horizontalCenter: parent.horizontalCenter; width: grid.cellWidth * 0.7; height: grid.cellHeight * 0.7}
                    Text { text: ctrl_id;anchors.horizontalCenter: parent.horizontalCenter; color: wrapper.GridView.isCurrentItem ?

"red" :"blue" }
                    Text { text: name;anchors.horizontalCenter: parent.horizontalCenter; color: wrapper.GridView.isCurrentItem ? "red" :"blue" }
                }

                MouseArea
                {
                    anchors.fill: parent
                    onClicked: grid.currentIndex = index
                }
            }
        }
        GridView {
            id:grid
            //anchors.fill: parent
            width: parent.width
            height: parent.height - space1.height
            anchors {top: space1.bottom;}
            cellWidth: parent.width * 0.25
            cellHeight: parent.width * 0.25
            //model: listModel
            model: myFirstModel
            delegate: msnDelegate
            highlight: Rectangle { color: "lightsteelblue"; radius: 5 }
            currentIndex: 2
            //focus: true
        }

C++代码:

sqlquerymodel.h

#ifndef SQLQUERYMODEL_H
#define SQLQUERYMODEL_H

#include <QSqlQueryModel>

class SqlQueryModel : public QSqlQueryModel
{
    Q_OBJECT

    void generateRoleNames();

public:
    explicit SqlQueryModel(QObject *parent = 0);

    void setQuery(const QString &query, const QSqlDatabase &db = QSqlDatabase());
    void setQuery(const QSqlQuery &query);
    QVariant data(const QModelIndex &index, int role) const;

    virtual QHash<int, QByteArray> roleNames() const;

signals:

public slots:

};

#endif // SQLQUERYMODEL_H

sqlquerymodel.cpp

#include "sqlquerymodel.h"
#include <QSqlRecord>
#include <QSqlField>
#include <QDebug>

SqlQueryModel::SqlQueryModel(QObject *parent) :
    QSqlQueryModel(parent)
{

}

void SqlQueryModel::setQuery(const QString &query, const QSqlDatabase &db)
{
    QSqlQueryModel::setQuery(query,db);
    generateRoleNames();
}

void SqlQueryModel::setQuery(const QSqlQuery & query)
{
    QSqlQueryModel::setQuery(query);
    generateRoleNames();
}

void SqlQueryModel::generateRoleNames()
{
    QHash<int, QByteArray> roleNames;
    for( int i = 0; i < record().count(); i++) {
        roleNames[Qt::UserRole + i + 1] = record().fieldName(i).toUtf8();
    }
    //setRoleNames(roleNames);
}

QHash<int, QByteArray> SqlQueryModel::roleNames() const
{
    QHash<int, QByteArray> roleNames;
    for( int i = 0; i < record().count(); i++) {
        roleNames[Qt::UserRole + i + 1] = record().fieldName(i).toUtf8();
    }
    return roleNames;
}

QVariant SqlQueryModel::data(const QModelIndex &index, int role) const
{
    QVariant value = QSqlQueryModel::data(index, role);
    if(role < Qt::UserRole)
    {
        value = QSqlQueryModel::data(index, role);
    }
    else
    {
        int columnIdx = role - Qt::UserRole - 1;
        QModelIndex modelIndex = this->index(index.row(), columnIdx);
        value = QSqlQueryModel::data(modelIndex, Qt::DisplayRole);
    }
    return value;
}

主函数中数据关联的代码:

    SqlQueryModel *model1 = new SqlQueryModel(0);
    model1->setQuery("SELECT * FROM ctrl_para");

    QtQuick2ApplicationViewer viewer;

    viewer.rootContext()->setContextProperty("myFirstModel", model1);

    viewer.setMainQmlFile(QStringLiteral("qml/SH_User/base.qml"));
    viewer.showExpanded();

注意:

query操作仅仅运行一次,所以要想实时显示数据库中的数据,能够定时读取数据库以动态显示数据