QSqlQueryModel露

PyQt5.QtSql.QSqlQueryModel

Description露

The QSqlQueryModel class provides a read-only data model for SQL result sets.

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:

#     QSqlQueryModel *model = new QSqlQueryModel;
#     model->setQuery("SELECT name, salary FROM employee");
#     model->setHeaderData(0, Qt::Horizontal, tr("Name"));
#     model->setHeaderData(1, Qt::Horizontal, tr("Salary"));

# #! [17]
#     QTableView *view = new QTableView;
# #! [17] #! [18]
#     view->setModel(model);
# #! [18] #! [19]
#     view->show();

We set the model鈥檚 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:

#     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. Assuming that salary is column 2, we can rewrite the last line as follows:

#     int salary = model.data(model.index(4, 2)).toInt();

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 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鈥檛 return the number of selected rows in a query, the model will fetch rows incrementally. See fetchMore() for more information.

Methods露

__init__(parent: QObject = None): Creates an empty QSqlQueryModel with the given parent.

beginInsertColumns(QModelIndex, int, int): TODO

beginInsertRows(QModelIndex, int, int): TODO

beginRemoveColumns(QModelIndex, int, int): TODO

beginRemoveRows(QModelIndex, int, int): TODO

beginResetModel(): TODO

canFetchMore(parent: QModelIndex = QModelIndex()) → bool: TODO

clear(): Clears the model and releases any acquired resource.

columnCount(parent: QModelIndex = QModelIndex()) → int: TODO

data(QModelIndex, role: int = DisplayRole) → Any: TODO

endInsertColumns(): TODO

endInsertRows(): TODO

endRemoveColumns(): TODO

endRemoveRows(): TODO

endResetModel(): TODO

fetchMore(parent: QModelIndex = QModelIndex()): TODO

headerData(int, Orientation, role: int = DisplayRole) → Any: TODO

indexInQuery(QModelIndex) → QModelIndex

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.

insertColumns(int, int, parent: QModelIndex = QModelIndex()) → bool: TODO

lastError() → QSqlError: Returns information about the last error that occurred on the database.

See also

setLastError(), query().

query() → QSqlQuery: Returns the QSqlQuery associated with this model.

See also

setQuery().

queryChange()

This virtual function is called whenever the query changes. The default implementation does nothing.

query() returns the new query.

See also

query(), setQuery().

record() → QSqlRecord

This is an overloaded function.

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.

See also

isEmpty().

record(int) → QSqlRecord

Returns the record containing information about the fields of the current query. 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.

See also

isEmpty().

removeColumns(int, int, parent: QModelIndex = QModelIndex()) → bool: TODO

roleNames() → Dict[int, QByteArray]

Returns the model鈥檚 role names.

Qt defines only one role for the QSqlQueryModel:

Qt Role	QML Role Name
DisplayRole	display

rowCount(parent: QModelIndex = QModelIndex()) → int: TODO

setHeaderData(int, Orientation, Any, role: int = EditRole) → bool: TODO

setLastError(QSqlError): Protected function which allows derived classes to set the value of the last error that occurred on the database to error.

See also

lastError().

setQuery(QSqlQuery)

Resets the model and sets the data provider to be the given 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.

Note: Calling will remove any inserted columns.

setQuery(str, db: QSqlDatabase = QSqlDatabase())

This is an overloaded function.

Executes the query query for the given database connection db. If no database (or an invalid 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:

# QSqlQueryModel model;
# model.setQuery("select * from MyTable");
# if (model.lastError().isValid())
#     qDebug() << model.lastError();

See also

query(), queryChange(), lastError().