QT 015 【数据库】 QSqlTableModel Class

Ref: http://doc.qt.io/qt-5/qsqltablemodel.html
1 小结

2 翻译：

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

16 public functions inherited from QSqlQueryModel

4 public functions inherited from QAbstractTableModel

39 public functions inherited from QAbstractItemModel

32 public functions inherited from QObject

Public Slots

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

2 public slots inherited from QAbstractItemModel

1 public slot inherited from QObject

Signals

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

18 signals inherited from QAbstractItemModel

2 signals inherited from QObject

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

3 protected functions inherited from QSqlQueryModel

19 protected functions inherited from QAbstractItemModel

9 protected functions inherited from QObject

Additional Inherited Members

1 property inherited from QObject

11 static public members inherited from QObject

1 protected slot inherited from QAbstractItemModel

Detailed Description

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

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,
andOnManualSubmit.

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 aQTableView.

QSqlTableModel provides no direct support for foreign keys.
Use the QSqlRelationalTableModeland 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 =
Q_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.

[virtual]

QSqlTableModel::~QSqlTableModel()

Destroys the object and frees any allocated resources.

[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().

[virtual]

void QSqlTableModel::clear()

Reimplemented from QSqlQueryModel::clear().

[virtual]

QVariant QSqlTableModel::data(const QModelIndex &index, introle =
Qt::DisplayRole) const

Reimplemented from QAbstractItemModel::data().

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().

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().

[virtual]

Qt::ItemFlags QSqlTableModel::flags(const QModelIndex &index)
const

Reimplemented from QAbstractItemModel::flags().

[virtual]

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

Reimplemented from QAbstractItemModel::headerData().

[virtual
protected]

QModelIndex QSqlTableModel::indexInQuery(constQModelIndex &item)
const

Reimplemented from QSqlQueryModel::indexInQuery().

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(constQSqlRecord &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().

[virtual]

bool QSqlTableModel::insertRows(int row, int count,
constQModelIndex &parent =
QModelIndex())

Reimplemented from QAbstractItemModel::insertRows().

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().

[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.

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().

[virtual]

bool QSqlTableModel::removeColumns(int column, int count,
const QModelIndex &parent =
QModelIndex())

Reimplemented from QAbstractItemModel::removeColumns().

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

Returns if the columns were successfully removed; otherwise returns

false

.

See also removeRows().

[virtual]

bool QSqlTableModel::removeRows(int row, int count,
constQModelIndex &parent =
QModelIndex())

Reimplemented from QAbstractItemModel::removeRows().

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
slot]

void QSqlTableModel::revert()

Reimplemented from 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]

void QSqlTableModel::revertRow(int row)

Reverts all changes for the specified row.

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

[virtual]

int QSqlTableModel::rowCount(const QModelIndex &parent =
QModelIndex()) const

Reimplemented from QAbstractItemModel::rowCount().

[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().

[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().

[virtual]

bool QSqlTableModel::setData(const QModelIndex &index,
constQVariant &value, int role =
Qt::EditRole)

Reimplemented from QAbstractItemModel::setData().

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.

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

[virtual]

void QSqlTableModel::setEditStrategy(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 aQSqlTableModel. 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 and determine whether the corresponding fields are used when changes are submitted to the database. The caller should remember
to set the generated flag to FALSE for fields where the database is meant to supply the value, such as an automatically incremented ID.

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().

[virtual]

void QSqlTableModel::sort(int column, Qt::SortOrder order)

Reimplemented from QAbstractItemModel::sort().

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

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

[virtual
slot]

bool QSqlTableModel::submit()

Reimplemented from 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 orOnFieldChange.
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().

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().