/**************************************************************************** ** ** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved. ** ** This file is part of the QtSql module of the Qt Toolkit. ** ** This file may be used under the terms of the GNU General Public ** License version 2.0 as published by the Free Software Foundation ** and appearing in the file LICENSE.GPL included in the packaging of ** this file. Please review the following information to ensure GNU ** General Public Licensing requirements will be met: ** http://www.trolltech.com/products/qt/opensource.html ** ** If you are unsure which license is appropriate for your use, please ** review the following information: ** http://www.trolltech.com/products/qt/licensing.html or contact the ** sales department at sales@trolltech.com. ** ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. ** ****************************************************************************/ #include "qsqlquerymodel.h" #include <qdebug.h> #include <qsqldriver.h> #include <qsqlfield.h> #include "qsqlquerymodel_p.h" #define QSQL_PREFETCH 255 void QSqlQueryModelPrivate::prefetch(int limit) { Q_Q(QSqlQueryModel); if (atEnd || limit <= bottom.row() || bottom.column() == -1) return; QModelIndex newBottom; const int oldBottomRow = qMax(bottom.row(), 0); // try to seek directly if (query.seek(limit)) { newBottom = q->createIndex(limit, bottom.column()); } else { // have to seek back to our old position for MS Access int i = oldBottomRow; if (query.seek(i)) { while (query.next()) ++i; newBottom = q->createIndex(i, bottom.column()); } else { // empty or invalid query newBottom = q->createIndex(-1, bottom.column()); } atEnd = true; // this is the end. } if (newBottom.row() >= 0 && newBottom.row() > bottom.row()) { q->beginInsertRows(QModelIndex(), bottom.row() + 1, newBottom.row()); bottom = newBottom; q->endInsertRows(); } else { bottom = newBottom; } } QSqlQueryModelPrivate::~QSqlQueryModelPrivate() { } /*! \class QSqlQueryModel \brief The QSqlQueryModel class provides a read-only data model for SQL result sets. \ingroup database \module sql QSqlQueryModel is a high-level interface for executing SQL statements and traversing the result set. It is built on top of the lower-level QSqlQuery and can be used to provide data to view classes such as QTableView. For example: \quotefromfile snippets/sqldatabase/sqldatabase.cpp \skipto QSqlQueryModel_snippets \skipto QSqlQueryModel *model \printuntil show() We set the model's query, then we set up the labels displayed in the view header. QSqlQueryModel can also be used to access a database programmatically, without binding it to a view: \skipto QSqlQueryModel model; \printuntil int salary = The code snippet above extracts the \c salary field from record 4 in the result set of the query \c{SELECT * from employee}. Assuming that \c salary is column 2, we can rewrite the last line as follows: \skipto int salary = \printline int salary = The model is read-only by default. To make it read-write, you must subclass it and reimplement setData() and flags(). Another option is to use QSqlTableModel, which provides a read-write model based on a single database table. The \l{sql/querymodel} example illustrates how to use QSqlQueryModel to display the result of a query. It also shows how to subclass QSqlQueryModel to customize the contents of the data before showing it to the user, and how to create a read-write model based on QSqlQueryModel. If the database doesn't return the amount of selected rows in a query, the model will fetch rows incrementally. See fetchMore() for more information. \sa QSqlTableModel, QSqlRelationalTableModel, QSqlQuery, {Model/View Programming}, {Query Model Example} */ /*! Creates an empty QSqlQueryModel with the given \a parent. */ 00129 QSqlQueryModel::QSqlQueryModel(QObject *parent) : QAbstractTableModel(*new QSqlQueryModelPrivate, parent) { } /*! \internal */ 00136 QSqlQueryModel::QSqlQueryModel(QSqlQueryModelPrivate &dd, QObject *parent) : QAbstractTableModel(dd, parent) { } /*! Destroys the object and frees any allocated resources. \sa clear() */ 00146 QSqlQueryModel::~QSqlQueryModel() { } /*! \since 4.1 Fetches more rows from a database. This only affects databases that don't report back the size of a query (see QSqlDriver::hasFeature()). To force fetching of the entire database, you can use the following: \code while (myModel->canFetchMore()) myModel->fetchMore(); \endcode \a parent should always be an invalid QModelIndex. \sa canFetchMore() */ 00168 void QSqlQueryModel::fetchMore(const QModelIndex &parent) { Q_D(QSqlQueryModel); if (parent.isValid()) return; d->prefetch(qMax(d->bottom.row(), 0) + QSQL_PREFETCH); } /*! \since 4.1 Returns true if it is possible to read more rows from the database. This only affects databases that don't report back the size of a query (see QSqlDriver::hasFeature()). \a parent should always be an invalid QModelIndex. \sa fetchMore() */ 00187 bool QSqlQueryModel::canFetchMore(const QModelIndex &parent) const { Q_D(const QSqlQueryModel); return (!parent.isValid() && !d->atEnd); } /*! \fn int QSqlQueryModel::rowCount(const QModelIndex &parent) const \since 4.1 If the database supports returning the size of a query (see QSqlDriver::hasFeature()), the amount of rows of the current query is returned. Otherwise, returns the amount of rows currently cached on the client. \a parent should always be an invalid QModelIndex. \sa canFetchMore(), QSqlDriver::hasFeature() */ 00205 int QSqlQueryModel::rowCount(const QModelIndex &index) const { Q_D(const QSqlQueryModel); return index.isValid() ? 0 : d->bottom.row() + 1; } /*! \reimp */ 00213 int QSqlQueryModel::columnCount(const QModelIndex &index) const { Q_D(const QSqlQueryModel); return index.isValid() ? 0 : d->rec.count(); } /*! Returns the value for the specified \a item and \a role. If \a item is out of bounds or if an error occurred, an invalid QVariant is returned. \sa lastError() */ 00227 QVariant QSqlQueryModel::data(const QModelIndex &item, int role) const { Q_D(const QSqlQueryModel); if (!item.isValid()) return QVariant(); QVariant v; if (role & ~(Qt::DisplayRole | Qt::EditRole)) return v; if (!d->rec.isGenerated(item.column())) return v; QModelIndex dItem = indexInQuery(item); if (dItem.row() > d->bottom.row()) const_cast<QSqlQueryModelPrivate *>(d)->prefetch(dItem.row()); if (!d->query.seek(dItem.row())) { d->error = d->query.lastError(); return v; } return d->query.value(dItem.column()); } /*! Returns the header data for the given \a role in the \a section of the header with the specified \a orientation. */ 00255 QVariant QSqlQueryModel::headerData(int section, Qt::Orientation orientation, int role) const { Q_D(const QSqlQueryModel); if (orientation == Qt::Horizontal) { QVariant val = d->headers.value(section).value(role); if (role == Qt::DisplayRole && !val.isValid()) val = d->headers.value(section).value(Qt::EditRole); if (val.isValid()) return val; if (role == Qt::DisplayRole && d->rec.count() > section) return d->rec.fieldName(section); } return QAbstractItemModel::headerData(section, orientation, role); } /*! This virtual function is called whenever the query changes. The default implementation does nothing. query() returns the new query. \sa query(), setQuery() */ 00278 void QSqlQueryModel::queryChange() { // do nothing } /*! Resets the model and sets the data provider to be the given \a query. Note that the query must be active and must not be isForwardOnly(). lastError() can be used to retrieve verbose information if there was an error setting the query. \sa query(), QSqlQuery::isActive(), QSqlQuery::setForwardOnly(), lastError() */ 00293 void QSqlQueryModel::setQuery(const QSqlQuery &query) { Q_D(QSqlQueryModel); QSqlRecord newRec = query.record(); bool columnsChanged = (newRec != d->rec); bool hasQuerySize = d->query.driver()->hasFeature(QSqlDriver::QuerySize); if (d->colOffsets.size() != newRec.count() || columnsChanged) { d->colOffsets.resize(newRec.count()); memset(d->colOffsets.data(), 0, d->colOffsets.size() * sizeof(int)); } beginRemoveRows(QModelIndex(), 0, qMax(d->bottom.row(), 0)); d->bottom = QModelIndex(); d->error = QSqlError(); d->atEnd = false; d->query = query; d->rec = newRec; endRemoveRows(); if (columnsChanged) reset(); if (!query.isActive() || query.isForwardOnly()) { d->atEnd = true; d->bottom = QModelIndex(); if (query.isForwardOnly()) d->error = QSqlError(QLatin1String("Forward-only queries " "cannot be used in a data model"), QString(), QSqlError::ConnectionError); else d->error = query.lastError(); return; } QModelIndex newBottom; if (hasQuerySize) { newBottom = createIndex(d->query.size() - 1, d->rec.count() - 1); beginInsertRows(QModelIndex(), 0, qMax(0, newBottom.row())); d->bottom = createIndex(d->query.size() - 1, columnsChanged ? 0 : d->rec.count() - 1); d->atEnd = true; endInsertRows(); } else { newBottom = createIndex(-1, d->rec.count() - 1); } d->bottom = newBottom; queryChange(); // fetchMore does the rowsInserted stuff for incremental models fetchMore(); } /*! \overload Executes the query \a query for the given database connection \a db. If no database is specified, the default connection is used. lastError() can be used to retrieve verbose information if there was an error setting the query. Example: \code QSqlQueryModel model; model.setQuery("select * from MyTable"); if (model.lastError().isValid()) qDebug() << model.lastError(); \endcode \sa query(), queryChange(), lastError() */ 00365 void QSqlQueryModel::setQuery(const QString &query, const QSqlDatabase &db) { setQuery(QSqlQuery(query, db)); } /*! Clears the model and releases any acquired resource. */ 00373 void QSqlQueryModel::clear() { Q_D(QSqlQueryModel); d->error = QSqlError(); d->atEnd = true; d->query.clear(); d->rec.clear(); d->colOffsets.clear(); d->bottom = QModelIndex(); d->headers.clear(); } /*! Sets the caption for a horizontal header for the specified \a role to \a value. This is useful if the model is used to display data in a view (e.g., QTableView). Returns true if \a orientation is Qt::Horizontal and the \a section refers to a valid section; otherwise returns false. Note that this function cannot be used to modify values in the database since the model is read-only. \sa data() */ 00399 bool QSqlQueryModel::setHeaderData(int section, Qt::Orientation orientation, const QVariant &value, int role) { Q_D(QSqlQueryModel); if (orientation != Qt::Horizontal || section < 0) return false; if (d->headers.size() <= section) d->headers.resize(qMax(section + 1, 16)); d->headers[section][role] = value; emit headerDataChanged(orientation, section, section); return true; } /*! Returns the QSqlQuery associated with this model. \sa setQuery() */ 00418 QSqlQuery QSqlQueryModel::query() const { Q_D(const QSqlQueryModel); return d->query; } /*! Returns information about the last error that occurred on the database. */ 00428 QSqlError QSqlQueryModel::lastError() const { Q_D(const QSqlQueryModel); return d->error; } /*! Protected function which allows derived classes to set the value of the last error that occurred on the database to \a error. \sa lastError() */ 00440 void QSqlQueryModel::setLastError(const QSqlError &error) { Q_D(QSqlQueryModel); d->error = error; } /*! Returns the record containing information about the fields of the current query. If \a row is the index of a valid row, the record will be populated with values from that row. If the model is not initialized, an empty record will be returned. \sa QSqlRecord::isEmpty() */ 00456 QSqlRecord QSqlQueryModel::record(int row) const { Q_D(const QSqlQueryModel); if (row < 0) return d->rec; QSqlRecord rec = d->rec; for (int i = 0; i < rec.count(); ++i) rec.setValue(i, data(createIndex(row, i), Qt::EditRole)); return rec; } /*! \overload Returns an empty record containing information about the fields of the current query. If the model is not initialized, an empty record will be returned. \sa QSqlRecord::isEmpty() */ 00478 QSqlRecord QSqlQueryModel::record() const { Q_D(const QSqlQueryModel); return d->rec; } /*! Inserts \a count columns into the model at position \a column. The \a parent parameter must always be an invalid QModelIndex, since the model does not support parent-child relationships. Returns true if \a column is within bounds; otherwise returns false. By default, inserted columns are empty. To fill them with data, reimplement data() and handle any inserted column separately: \quotefromfile snippets/sqldatabase/sqldatabase.cpp \skipto QSqlQueryModel_snippets \skipto MyModel::data( \printuntil /^\}/ \sa removeColumns() */ 00501 bool QSqlQueryModel::insertColumns(int column, int count, const QModelIndex &parent) { Q_D(QSqlQueryModel); if (count <= 0 || parent.isValid() || column < 0 || column > d->rec.count()) return false; beginInsertColumns(parent, column, column + count - 1); for (int c = 0; c < count; ++c) { QSqlField field; field.setReadOnly(true); field.setGenerated(false); d->rec.insert(column, field); if (d->colOffsets.size() < d->rec.count()) { int nVal = d->colOffsets.isEmpty() ? 0 : d->colOffsets[d->colOffsets.size() - 1]; d->colOffsets.append(nVal); Q_ASSERT(d->colOffsets.size() >= d->rec.count()); } for (int i = column + 1; i < d->colOffsets.count(); ++i) ++d->colOffsets[i]; } endInsertColumns(); return true; } /*! Removes \a count columns from the model starting from position \a column. The \a parent parameter must always be an invalid QModelIndex, since the model does not support parent-child relationships. Removing columns effectively hides them. It does not affect the underlying QSqlQuery. Returns true if the columns were removed; otherwise returns false. */ 00536 bool QSqlQueryModel::removeColumns(int column, int count, const QModelIndex &parent) { Q_D(QSqlQueryModel); if (count <= 0 || parent.isValid() || column < 0 || column >= d->rec.count()) return false; beginRemoveColumns(parent, column, column + count - 1); int i; for (i = 0; i < count; ++i) d->rec.remove(column); for (i = column; i < d->colOffsets.count(); ++i) d->colOffsets[i] -= count; endRemoveColumns(); return true; } /*! Returns the index of the value in the database result set for the given \a item in the model. The return value is identical to \a item if no columns or rows have been inserted, removed, or moved around. Returns an invalid model index if \a item is out of bounds or if \a item does not point to a value in the result set. \sa QSqlTableModel::indexInQuery(), insertColumns(), removeColumns() */ 00566 QModelIndex QSqlQueryModel::indexInQuery(const QModelIndex &item) const { Q_D(const QSqlQueryModel); if (item.column() < 0 || item.column() >= d->rec.count() || !d->rec.isGenerated(item.column())) return QModelIndex(); return createIndex(item.row(), item.column() - d->colOffsets[item.column()], item.internalPointer()); }