QSqlTableModel Class

The QSqlTableModel class provides an editable data model for a single database table. More...

Header:	#include <QSqlTableModel>
qmake:	QT += sql
Inherits:	QSqlQueryModel
Inherited By:	QSqlRelationalTableModel

• List of all members, including inherited members

Public Types

enum	EditStrategy { OnFieldChange, OnRowChange, OnManualSubmit }

Public Functions

	QSqlTableModel(QObject *parent = nullptr, QSqlDatabase db = QSqlDatabase())
virtual	~QSqlTableModel()
QSqlDatabase	database() const
QSqlTableModel::EditStrategy	editStrategy() const
int	fieldIndex(const QString &fieldName) const
QString	filter() const
bool	insertRecord(int row, const QSqlRecord &record)
bool	isDirty(const QModelIndex &index) const
bool	isDirty() const
QSqlIndex	primaryKey() const
QSqlRecord	record() const
QSqlRecord	record(int row) const
virtual void	revertRow(int row)
virtual void	setEditStrategy(QSqlTableModel::EditStrategy strategy)
virtual void	setFilter(const QString &filter)
bool	setRecord(int row, const QSqlRecord &values)
virtual void	setSort(int column, Qt::SortOrder order)
virtual void	setTable(const QString &tableName)
QString	tableName() const

Reimplemented Public Functions

virtual void	clear() override
virtual QVariant	data(const QModelIndex &index, int role = Qt::DisplayRole) const override
virtual Qt::ItemFlags	flags(const QModelIndex &index) const override
virtual QVariant	headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override
virtual bool	insertRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
virtual bool	removeColumns(int column, int count, const QModelIndex &parent = QModelIndex()) override
virtual bool	removeRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
virtual int	rowCount(const QModelIndex &parent = QModelIndex()) const override
virtual bool	setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override
virtual void	sort(int column, Qt::SortOrder order) override

Public Slots

virtual void	revert() override
void	revertAll()
virtual bool	select()
virtual bool	selectRow(int row)
virtual bool	submit() override
bool	submitAll()

Signals

void	beforeDelete(int row)
void	beforeInsert(QSqlRecord &record)
void	beforeUpdate(int row, QSqlRecord &record)
void	primeInsert(int row, QSqlRecord &record)

Protected Functions

virtual bool	deleteRowFromTable(int row)
virtual bool	insertRowIntoTable(const QSqlRecord &values)
virtual QString	orderByClause() const
QSqlRecord	primaryValues(int row) const
virtual QString	selectStatement() const
void	setPrimaryKey(const QSqlIndex &key)
void	setQuery(const QSqlQuery &query)
virtual bool	updateRowInTable(int row, const QSqlRecord &values)

Reimplemented Protected Functions

virtual QModelIndex

indexInQuery(const QModelIndex &item) const override

Detailed Description

QSqlTableModel is a high-level interface for reading and writing database records from a single table. 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:

    QSqlTableModel *model = new QSqlTableModel(parentObject, database);
    model->setTable("employee");
    model->setEditStrategy(QSqlTableModel::OnManualSubmit);
    model->select();
    model->setHeaderData(0, Qt::Horizontal, tr("Name"));
    model->setHeaderData(1, Qt::Horizontal, tr("Salary"));

    QTableView *view = new QTableView;
    view->setModel(model);
    view->hideColumn(0); // don't show the ID
    view->show();

We set the SQL table's name and the edit strategy, then we set up the labels displayed in the view header. The edit strategy dictates when the changes done by the user in the view are actually applied to the database. The possible values are OnFieldChange, OnRowChange, and OnManualSubmit.

QSqlTableModel can also be used to access a database programmatically, without binding it to a view:

    QSqlTableModel model;
    model.setTable("employee");
    model.select();
    int salary = model.record(4).value("salary").toInt();

The code snippet above extracts the salary field from record 4 in the result set of the query SELECT * from employee.

It is possible to set filters using setFilter(), or modify the sort order using setSort(). At the end, you must call select() to populate the model with data.

The tablemodel example illustrates how to use QSqlTableModel as the data source for a QTableView.

QSqlTableModel provides no direct support for foreign keys. Use the QSqlRelationalTableModel and QSqlRelationalDelegate if you want to resolve foreign keys.

See also QSqlRelationalTableModel, QSqlQuery, Model/View Programming, Table Model Example, and Cached Table Example.

Member Type Documentation

enum QSqlTableModel::EditStrategy

This enum type describes which strategy to choose when editing values in the database.

Constant	Value	Description
QSqlTableModel::OnFieldChange	0	All changes to the model will be applied immediately to the database.
QSqlTableModel::OnRowChange	1	Changes to a row will be applied when the user selects a different row.
QSqlTableModel::OnManualSubmit	2	All changes will be cached in the model until either submitAll() or revertAll() is called.

Note: To prevent inserting only partly initialized rows into the database, OnFieldChange will behave like OnRowChange for newly inserted rows.

See also setEditStrategy().

Member Function Documentation

QSqlTableModel::QSqlTableModel(QObject *parent = nullptr, QSqlDatabase db = QSqlDatabase())

Creates an empty QSqlTableModel and sets the parent to parent and the database connection to db. If db is not valid, the default database connection will be used.

The default edit strategy is OnRowChange.

[signal] void QSqlTableModel::beforeDelete(int row)

This signal is emitted by deleteRowFromTable() before the row is deleted from the currently active database table.

[signal] void QSqlTableModel::beforeInsert(QSqlRecord &record)

This signal is emitted by insertRowIntoTable() before a new row is inserted into the currently active database table. The values that are about to be inserted are stored in record and can be modified before they will be inserted.

[signal] void QSqlTableModel::beforeUpdate(int row, QSqlRecord &record)

This signal is emitted by updateRowInTable() before the row is updated in the currently active database table with the values from record.

Note that only values that are marked as generated will be updated. The generated flag can be set with QSqlRecord::setGenerated() and checked with QSqlRecord::isGenerated().

See also QSqlRecord::isGenerated().

[signal] void QSqlTableModel::primeInsert(int row, QSqlRecord &record)

This signal is emitted by insertRows(), when an insertion is initiated in the given row of the currently active database table. The record parameter can be written to (since it is a reference), for example to populate some fields with default values and set the generated flags of the fields. Do not try to edit the record via other means such as setData() or setRecord() while handling this signal.

[override virtual slot] void QSqlTableModel::revert()

Reimplements: QAbstractItemModel::revert().

This reimplemented slot is called by the item delegates when the user canceled editing the current row.

Reverts the changes if the model's strategy is set to OnRowChange or OnFieldChange. Does nothing for the OnManualSubmit strategy.

Use revertAll() to revert all pending changes for the OnManualSubmit strategy or revertRow() to revert a specific row.

See also submit(), submitAll(), revertRow(), and revertAll().

[slot] void QSqlTableModel::revertAll()

Reverts all pending changes.

See also revert(), revertRow(), and submitAll().

[virtual slot] bool QSqlTableModel::select()

Populates the model with data from the table that was set via setTable(), using the specified filter and sort condition, and returns true if successful; otherwise returns false.

Note: Calling select() will revert any unsubmitted changes and remove any inserted columns.

See also setTable(), setFilter(), and selectStatement().

[virtual slot] bool QSqlTableModel::selectRow(int row)

Refreshes row in the model with values from the database table row matching on primary key values. Without a primary key, all column values must match. If no matching row is found, the model will show an empty row.

Returns true if successful; otherwise returns false.

This function was introduced in Qt 5.0.

See also select().

[override virtual slot] bool QSqlTableModel::submit()

Reimplements: QAbstractItemModel::submit().

This reimplemented slot is called by the item delegates when the user stopped editing the current row.

Submits the currently edited row if the model's strategy is set to OnRowChange or OnFieldChange. Does nothing for the OnManualSubmit strategy.

Use submitAll() to submit all pending changes for the OnManualSubmit strategy.

Returns true on success; otherwise returns false. Use lastError() to query detailed error information.

Does not automatically repopulate the model. Submitted rows are refreshed from the database on success.

See also revert(), revertRow(), submitAll(), revertAll(), and lastError().

[slot] bool QSqlTableModel::submitAll()

Submits all pending changes and returns true on success. Returns false on error, detailed error information can be obtained with lastError().

In OnManualSubmit, on success the model will be repopulated. Any views presenting it will lose their selections.

Note: In OnManualSubmit mode, already submitted changes won't be cleared from the cache when submitAll() fails. This allows transactions to be rolled back and resubmitted without losing data.

See also revertAll() and lastError().

[virtual] QSqlTableModel::~QSqlTableModel()

Destroys the object and frees any allocated resources.

[override virtual] void QSqlTableModel::clear()

Reimplements: QSqlQueryModel::clear().

[override virtual] QVariant QSqlTableModel::data(const QModelIndex &index, int role = Qt::DisplayRole) const

Reimplements: QSqlQueryModel::data(const QModelIndex &item, int role) const.

See also setData().

QSqlDatabase QSqlTableModel::database() const

Returns the model's database connection.

[virtual protected] bool QSqlTableModel::deleteRowFromTable(int row)

Deletes the given row from the currently active database table.

This is a low-level method that operates directly on the database and should not be called directly. Use removeRow() or removeRows() to delete values. The model will decide depending on its edit strategy when to modify the database.

Returns true if the row was deleted; otherwise returns false.

See also removeRow() and removeRows().

QSqlTableModel::EditStrategy QSqlTableModel::editStrategy() const

Returns the current edit strategy.

See also setEditStrategy().

int QSqlTableModel::fieldIndex(const QString &fieldName) const

Returns the index of the field fieldName, or -1 if no corresponding field exists in the model.

QString QSqlTableModel::filter() const

Returns the currently set filter.

See also setFilter() and select().

[override virtual] Qt::ItemFlags QSqlTableModel::flags(const QModelIndex &index) const

Reimplements: QAbstractTableModel::flags(const QModelIndex &index) const.

[override virtual] QVariant QSqlTableModel::headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const

Reimplements: QSqlQueryModel::headerData(int section, Qt::Orientation orientation, int role) const.

[override virtual protected] QModelIndex QSqlTableModel::indexInQuery(const QModelIndex &item) const

Reimplements: QSqlQueryModel::indexInQuery(const QModelIndex &item) const.

Returns the index of the value in the database result set for the given item in the model.

The return value is identical to item if no columns or rows have been inserted, removed, or moved around.

Returns an invalid model index if item is out of bounds or if item does not point to a value in the result set.

See also QSqlQueryModel::indexInQuery().

bool QSqlTableModel::insertRecord(int row, const QSqlRecord &record)

Inserts the record at position row. If row is negative, the record will be appended to the end. Calls insertRows() and setRecord() internally.

Returns true if the record could be inserted, otherwise false.

Changes are submitted immediately for OnFieldChange and OnRowChange. Failure does not leave a new row in the model.

See also insertRows(), removeRows(), and setRecord().

[virtual protected] bool QSqlTableModel::insertRowIntoTable(const QSqlRecord &values)

Inserts the values values into the currently active database table.

This is a low-level method that operates directly on the database and should not be called directly. Use insertRow() and setData() to insert values. The model will decide depending on its edit strategy when to modify the database.

Returns true if the values could be inserted, otherwise false. Error information can be retrieved with lastError().

See also lastError(), insertRow(), and insertRows().

[override virtual] bool QSqlTableModel::insertRows(int row, int count, const QModelIndex &parent = QModelIndex())

Reimplements: QAbstractItemModel::insertRows(int row, int count, const QModelIndex &parent).

Inserts count empty rows at position row. Note that parent must be invalid, since this model does not support parent-child relations.

For edit strategies OnFieldChange and OnRowChange, only one row may be inserted at a time and the model may not contain other cached changes.

The primeInsert() signal will be emitted for each new row. Connect to it if you want to initialize the new row with default values.

Does not submit rows, regardless of edit strategy.

Returns false if the parameters are out of bounds or the row cannot be inserted; otherwise returns true.

See also primeInsert() and insertRecord().

bool QSqlTableModel::isDirty(const QModelIndex &index) const

Returns true if the value at the index index is dirty, otherwise false. Dirty values are values that were modified in the model but not yet written into the database.

If index is invalid or points to a non-existing row, false is returned.

bool QSqlTableModel::isDirty() const

This is an overloaded function.

Returns true if the model contains modified values that have not been committed to the database, otherwise false.

This function was introduced in Qt 5.0.

[virtual protected] QString QSqlTableModel::orderByClause() const

Returns an SQL ORDER BY clause based on the currently set sort order.

See also setSort() and selectStatement().

QSqlIndex QSqlTableModel::primaryKey() const

Returns the primary key for the current table, or an empty QSqlIndex if the table is not set or has no primary key.

See also setTable(), setPrimaryKey(), and QSqlDatabase::primaryIndex().

[protected] QSqlRecord QSqlTableModel::primaryValues(int row) const

Returns a record containing the fields represented in the primary key set to the values at row. If no primary key is defined, the returned record will contain all fields.

This function was introduced in Qt 5.1.

See also primaryKey().

QSqlRecord QSqlTableModel::record() const

This is an overloaded function.

It returns an empty record, having only the field names. This function can be used to retrieve the field names of a record.

See also setRecord() and QSqlRecord::isEmpty().

QSqlRecord QSqlTableModel::record(int row) const

Returns the record at row in the model.

If 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.

This function was introduced in Qt 5.0.

See also QSqlRecord::isEmpty().

[override virtual] bool QSqlTableModel::removeColumns(int column, int count, const QModelIndex &parent = QModelIndex())

Reimplements: QSqlQueryModel::removeColumns(int column, int count, const QModelIndex &parent).

Removes count columns from the parent model, starting at index column.

Returns if the columns were successfully removed; otherwise returns false.

See also removeRows().

[override virtual] bool QSqlTableModel::removeRows(int row, int count, const QModelIndex &parent = QModelIndex())

Reimplements: QAbstractItemModel::removeRows(int row, int count, const QModelIndex &parent).

Removes count rows starting at row. Since this model does not support hierarchical structures, parent must be an invalid model index.

When the edit strategy is OnManualSubmit, deletion of rows from the database is delayed until submitAll() is called.

For OnFieldChange and OnRowChange, only one row may be deleted at a time and only if no other row has a cached change. Deletions are submitted immediately to the database. The model retains a blank row for successfully deleted row until refreshed with select().

After failed deletion, the operation is not reverted in the model. The application may resubmit or revert.

Inserted but not yet successfully submitted rows in the range to be removed are immediately removed from the model.

Before a row is deleted from the database, the beforeDelete() signal is emitted.

If row < 0 or row + count > rowCount(), no action is taken and false is returned. Returns true if all rows could be removed; otherwise returns false. Detailed database error information can be retrieved using lastError().

See also removeColumns() and insertRows().

[virtual] void QSqlTableModel::revertRow(int row)

Reverts all changes for the specified row.

See also revert(), revertAll(), submit(), and submitAll().

[override virtual] int QSqlTableModel::rowCount(const QModelIndex &parent = QModelIndex()) const

Reimplements: QSqlQueryModel::rowCount(const QModelIndex &parent) const.

[virtual protected] QString QSqlTableModel::selectStatement() const

Returns the SQL SELECT statement used internally to populate the model. The statement includes the filter and the ORDER BY clause.

See also filter() and orderByClause().

[override virtual] bool QSqlTableModel::setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole)

Reimplements: QAbstractItemModel::setData(const QModelIndex &index, const QVariant &value, int role).

Sets the data for the item index for the role role to value.

For edit strategy OnFieldChange, an index may receive a change only if no other index has a cached change. Changes are submitted immediately. However, rows that have not yet been inserted in the database may be freely changed and are not submitted automatically. Submitted changes are not reverted upon failure.

For OnRowChange, an index may receive a change only if no other row has a cached change. Changes are not submitted automatically.

Returns true if value is equal to the current value. However, the value will not be submitted to the database.

Returns true if the value could be set or false on error, for example if index is out of bounds.

Returns false if the role is not Qt::EditRole. To set data for roles other than EditRole, either use a custom proxy model or subclass QSqlTableModel.

See also editStrategy(), data(), submit(), submitAll(), and revertRow().

[virtual] void QSqlTableModel::setEditStrategy(QSqlTableModel::EditStrategy strategy)

Sets the strategy for editing values in the database to strategy.

This will revert any pending changes.

See also editStrategy() and revertAll().

[virtual] void QSqlTableModel::setFilter(const QString &filter)

Sets the current filter to filter.

The filter is a SQL WHERE clause without the keyword WHERE (for example, name='Josephine').

If the model is already populated with data from a database, the model re-selects it with the new filter. Otherwise, the filter will be applied the next time select() is called.

See also filter(), select(), selectStatement(), and orderByClause().

[protected] void QSqlTableModel::setPrimaryKey(const QSqlIndex &key)

Protected method that allows subclasses to set the primary key to key.

Normally, the primary index is set automatically whenever you call setTable().

See also primaryKey() and QSqlDatabase::primaryIndex().

[protected] void QSqlTableModel::setQuery(const QSqlQuery &query)

This function simply calls QSqlQueryModel::setQuery(query). You should normally not call it on a QSqlTableModel. Instead, use setTable(), setSort(), setFilter(), etc., to set up the query.

See also selectStatement().

bool QSqlTableModel::setRecord(int row, const QSqlRecord &values)

Applies values to the row in the model. The source and target fields are mapped by field name, not by position in the record.

Note that the generated flags in values are preserved to determine whether the corresponding fields are used when changes are submitted to the database. By default, it is set to true for all fields in a QSqlRecord. You must set the flag to false using setGenerated(false) for any value in values, to save changes back to the database.

For edit strategies OnFieldChange and OnRowChange, a row may receive a change only if no other row has a cached change. Changes are submitted immediately. Submitted changes are not reverted upon failure.

Returns true if all the values could be set; otherwise returns false.

See also record() and editStrategy().

[virtual] void QSqlTableModel::setSort(int column, Qt::SortOrder order)

Sets the sort order for column to order. This does not affect the current data, to refresh the data using the new sort order, call select().

See also sort(), select(), and orderByClause().

[virtual] void QSqlTableModel::setTable(const QString &tableName)

Sets the database table on which the model operates to tableName. Does not select data from the table, but fetches its field information.

To populate the model with the table's data, call select().

Error information can be retrieved with lastError().

See also select(), setFilter(), and lastError().

[override virtual] void QSqlTableModel::sort(int column, Qt::SortOrder order)

Reimplements: QAbstractItemModel::sort(int column, Qt::SortOrder order).

Sorts the data by column with the sort order order. This will immediately select data, use setSort() to set a sort order without populating the model with data.

See also setSort(), select(), and orderByClause().

QString QSqlTableModel::tableName() const

Returns the name of the currently selected table.

[virtual protected] bool QSqlTableModel::updateRowInTable(int row, const QSqlRecord &values)

Updates the given row in the currently active database table with the specified values. Returns true if successful; otherwise returns false.

This is a low-level method that operates directly on the database and should not be called directly. Use setData() to update values. The model will decide depending on its edit strategy when to modify the database.

Note that only values that have the generated-flag set are updated. The generated-flag can be set with QSqlRecord::setGenerated() and tested with QSqlRecord::isGenerated().

See also QSqlRecord::isGenerated() and setData().