QML interacting with C + +: Using Qsqlquerymodel to display database data in QML

QML interacting with C + +: Using Qsqlquerymodel to display database data in QML

This blog link: http://blog.csdn.net/jdh99, author: jdh, reprint please specify.

Reference Links:

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

Environment:

Host: WIN7

Development environment: Qt5.2.1

Description

The database cannot be manipulated directly in QML, so the Qsqlquerymodel is encapsulated as a subclass and used as a property for QML

:

Source:

The code in the QML file that is responsible for data hosting display:

< Span style= "line-height:25.98958396911621px" >

Component {id:msndelegate Item {id:wrapper width : Grid.cellwidth; Height:grid.cellHeight Column {image{Source: "Pics/light_on.png"; ancho Rs.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:gr ID//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 + + code:

Sqlquerymodel.h

#ifndef sqlquerymodel_h#define sqlquerymodel_h#include <qsqlquerymodel>class sqlquerymodel:public qsqlquerymodel{    q_object    void Generaterolenames ();p ublic:    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

< Span style= "line-height:25.98958396911621px" >

#include "sqlquerymodel.h" #include <QSqlRecord> #include <QSqlField> #include <QDebug> Sqlquerymodel::sqlquerymodel (Qobject *parent): Qsqlquerymodel (parent) {}void sqlquerymodel::setquery (const QString &    Amp;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::d ata (const qmodelindex &index, int role) const{qvariant value = Qsqlquerymodel::d ata (index, role);    if (role < qt::userrole) {value = Qsqlquerymodel::d ata (index, role);        } else {int columnidx = role-qt::userrole-1;        Qmodelindex Modelindex = This->index (Index.row (), COLUMNIDX);    Value = Qsqlquerymodel::d ata (Modelindex, Qt::D isplayrole); } return value;

In the main function code associated with the data:

    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 ();

Attention:

The query operation executes only once, so if you want to display the data in the database in real time, you can read the database periodically to display the data dynamically.