Qt 4 provides a powerful model / view pattern to display custom data in various views – QListView, QTableView, etc. The problem is that the documentation for model/view programming is massive and it’s difficult to find simple examples on how to create custom models, custom views, etc.

So below is a simple example on how to create a custom model for a QListView. The model takes a std::vector of custom objects, and provides all the necessary methods. I’ve only included the minimal code so that you can get something working quickly, but of course the model can be further customized (see QAbstractListModel reference for instance).

EmployeeListModel.h

class EmployeeListModel : public QAbstractListModel {
	
	Q_OBJECT

public:

	explicit EmployeeListModel(const std::vector<Employee*>& employees, QObject* parent = 0);
	int rowCount(const QModelIndex &parent = QModelIndex()) const;
	QVariant data(const QModelIndex &index, int role) const;
	
private:
	
	std::vector<Employee*> employees_;
	
};

EmployeeListModel.cpp

#include "EmployeeListModel.h"

EmployeeListModel::EmployeeListModel(const std::vector<Employee*>& employees, QObject *parent) : QAbstractListModel(parent) {
	employees_ = employees;
}

int EmployeeListModel::rowCount(const QModelIndex& parent) const {
	return employees_.size();
}

QVariant EmployeeListModel::data(const QModelIndex& index, int role) const {
	// Check that the index is valid and within the correct range first:
	if (!index.isValid()) return QVariant();
	if (index.row() >= decks_.size()) return QVariant();
	
	if (role == Qt::DisplayRole) {
		// Only returns something for the roles you support (DisplayRole is a minimum)
		// Here we assume that the "Employee" class has a "lastName" method but of course any string can be returned
		return QVariant(employees_.at(index.row())->lastName());
	} else {
		return QVariant();	
	}
}

Usage:

EmployeeListModel* model = new EmployeeListModel(employees);
ui->employeeListView->setModel(model);

Tags: gui, mvc, qt, simple example

This entry was posted on Tuesday, August 2nd, 2011 at 6:53 and is filed under C++, Qt Framework. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.