Sort and Filter a QSqlQueryModel

QSortFilterSqlQueryModel is a QSqlQueryModel subclass that allows server-side sorting and filtering.

Feel free to download and test it.

Example usage

QSortFilterSqlQueryModel *model = new QSortFilterSqlQueryModel(this);
model->setQuery("SELECT u.id, u.name, c.name FROM users AS u LEFT JOIN cities AS c ON (u.city_id = c.id)");
model->setFilterColumn("u.name"); // will filter by user name
model->setFilterFlags(Qt::MatchStartsWith);
model->setFilter("Iv");
model->select();

/* executes this query:
SELECT u.id, u.name, c.name FROM users AS u LEFT JOIN cities AS c ON (u.city_id = c.id)
WHERE u.name LIKE 'Iv%'
*/

You can connect a QLineEdit's textChanged signal to the filter slot: filter is the same as setFilter, but it also call select();

// dynamic filtering on user input
QLineEdit *search = new QLineEdit(this);
connect(search, SIGNAL (textChanged(QString)), model, SLOT (filter(QString)));

Sorting is done automatically by the view, using the sort implementation. You can also use setSort to set a sort order before select()ing.

Warnings

It has only been tested in Windows using MySQL

• It won't work using setQuery(QSqlQuery). I didn't needed it so you have to reimplement it yourself.
• Works for me. May not work for you. :P

Code

QSortFilterSqlQueryModel.h

#ifndef QSORTFILTERSQLQUERYMODEL_H
#define QSORTFILTERSQLQUERYMODEL_H

#include <QSqlQueryModel>
#include <QSqlRecord>

class QSortFilterSqlQueryModel : public QSqlQueryModel
{
 Q_OBJECT

public:

explicit QSortFilterSqlQueryModel(QObject *parent = 0);

//void setQuery(const QSqlQuery &query);
 void setQuery(const QString & query, const QSqlDatabase & db = QSqlDatabase::database() );

public slots:

void setFilterColumn (const QString & column);
 void setFilterFlags (const Qt::MatchFlag flags);
 void setFilter( const QString & filter );
 void filter( const QString & filter );

void select();

virtual void setSort (int column, Qt::SortOrder order);
 virtual void sort (int column, Qt::SortOrder order);

private:

QSqlDatabase queryDB;
 QString queryClause;
 Qt::MatchFlag filterFlags;
 QString filterString;
 QString filterColumn;
 int sortKeyColumn;
 Qt::SortOrder sortOrder;

signals:

};

#endif // QSORTFILTERSQLQUERYMODEL_H

QSortFilterSqlQueryModel.cpp

#include "QSortFilterSqlQueryModel.h"
#include <QtSql>
#include <QString>

QSortFilterSqlQueryModel::QSortFilterSqlQueryModel(QObject* parent)
    : QSqlQueryModel(parent) {}

void QSortFilterSqlQueryModel::setQuery(const QString& query,
                                        const QSqlDatabase& db) {
    queryClause = query;
    queryDB = db;

    filterString.clear();
    // filterColumn.clear();
    filterFlags = Qt::MatchStartsWith;
    sortKeyColumn = –1;
    sortOrder = Qt::AscendingOrder;
}

void QSortFilterSqlQueryModel::select() {
    if (queryClause.isEmpty() || (!queryDB.isValid()))
        return;

    QString query = queryClause;

    if (!filterString.isEmpty() && !filterColumn.isEmpty()) {
        QString whereClause;
        QString esFilterString = filterString;
        QString esFilterColumn = filterColumn;

        if (filterFlags &
                Qt::MatchExactly) {  // totaly wrong :) Qt::MatchExacly = 0 & 0
            whereClause = "WHERE %1 = %2";
        } else if (filterFlags & Qt::MatchStartsWith) {
            whereClause = "WHERE %1 LIKE %2";
            esFilterString.append("");
        } else if (filterFlags & Qt::MatchEndsWith) {
            whereClause = "WHERE %1 LIKE %2";
            esFilterString.prepend("*");
        } else if (filterFlags & Qt::MatchRegExp) {
            whereClause = "WHERE %1 REGEXP %2";
        } else if (filterFlags & Qt::MatchWildcard) {
            whereClause = "WHERE %1 LIKE %2";
        } else if (filterFlags & Qt::MatchContains) {
            whereClause = "WHERE %1 LIKE 2";
            esFilterString.append("");
            esFilterString.prepend("");
        } else {
            return;
        }  // unhandled filterflag

        QSqlDriver* driver = queryDB.driver();
        esFilterColumn =
            driver->escapeIdentifier(filterColumn, QSqlDriver::FieldName);
        QSqlField field;
        field.setType(QVariant::String);
        field.setValue(esFilterString);
        esFilterString = driver->formatValue(field);
        if (filterFlags & Qt::MatchStartsWith || Qt::MatchEndsWith ||
                Qt::MatchWildcard) {
            esFilterString = esFilterString.replace("", "");
            // if (filterFlags & Qt::MatchWildcard)
            esFilterString = esFilterString.replace("*", "");
        }

        // whereClause.arg(esFilterColumn).arg(esFilterString); // don't know why it
        // doesn't work
        whereClause =
            whereClause.replace("%1", esFilterColumn).replace("%2", esFilterString);
        query.append(" " + whereClause);
    }

    if (sortKeyColumn >= 0) {
        QString orderClause;
        orderClause = "ORDER BY " + QString::number(sortKeyColumn + 1) + " " +
                      ((sortOrder == Qt::AscendingOrder) ? "ASC" : "DESC");
        query.append(" " + orderClause);
    }

    QSqlQueryModel::setQuery(query, queryDB);
}

void QSortFilterSqlQueryModel::setSort(int column, Qt::SortOrder order) {
    sortKeyColumn = column;
    sortOrder = order;
}

void QSortFilterSqlQueryModel::sort(int column, Qt::SortOrder order) {
    if ((sortKeyColumn != column) || (sortOrder != order)) {
        setSort(column, order);
        select();
    }
}

void QSortFilterSqlQueryModel::setFilterColumn(const QString& column) {
    filterColumn = column;
}

void QSortFilterSqlQueryModel::setFilter(const QString& filter) {
    filterString = filter;
}

void QSortFilterSqlQueryModel::setFilterFlags(const Qt::MatchFlag flags) {
    filterFlags = flags;
}

void QSortFilterSqlQueryModel::filter(const QString& filter) {
    if (filterString != filter) {
        setFilter(filter);
        select();
    }
}