|
|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QObject
com.trolltech.qt.core.QAbstractItemModel
com.trolltech.qt.gui.QAbstractTableModel
com.trolltech.qt.sql.QSqlQueryModel
public class QSqlQueryModel
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")); QTableView *view = new QTableView; view->setModel(model); view->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:
QSqlQueryModel model; model.setQuery("SELECT * FROM employee"); 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 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.
Model Example
Nested Class Summary |
---|
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
---|
QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I> |
Field Summary |
---|
Fields inherited from class com.trolltech.qt.core.QAbstractItemModel |
---|
dataChanged, headerDataChanged, layoutAboutToBeChanged, layoutChanged |
Constructor Summary | |
---|---|
QSqlQueryModel()
Equivalent to QSqlQueryModel(0). |
|
QSqlQueryModel(QObject parent)
Creates an empty QSqlQueryModel with the given parent. |
Method Summary | |
---|---|
boolean |
canFetchMore(QModelIndex parent)
Returns true if it is possible to read more rows from the database. |
void |
clear()
Clears the model and releases any acquired resource. |
int |
columnCount(QModelIndex parent)
This function is reimplemented for internal reasons. |
java.lang.Object |
data(QModelIndex item,
int role)
Returns the value for the specified item and role. |
void |
fetchMore(QModelIndex parent)
Fetches more rows from a database. |
static QSqlQueryModel |
fromNativePointer(QNativePointer nativePointer)
This function returns the QSqlQueryModel instance pointed to by nativePointer |
java.lang.Object |
headerData(int section,
Qt.Orientation orientation,
int role)
Returns the header data for the given role in the section of the header with the specified orientation. |
protected QModelIndex |
indexInQuery(QModelIndex item)
Returns the index of the value in the database result set for the given item in the model. |
boolean |
insertColumns(int column,
int count,
QModelIndex parent)
Inserts count columns into the model at position column. |
QSqlError |
lastError()
Returns information about the last error that occurred on the database. |
QSqlQuery |
query()
Returns the QSqlQuery associated with this model. |
protected void |
queryChange()
This virtual function is called whenever the query changes. |
QSqlRecord |
record()
Returns an empty record containing information about the fields of the current query. |
QSqlRecord |
record(int row)
Returns the record containing information about the fields of the current query. |
boolean |
removeColumns(int column,
int count,
QModelIndex parent)
Removes count columns from the model starting from position column. |
int |
rowCount(QModelIndex parent)
If the database supports returning the size of a query (see QSqlDriver::hasFeature()), the amount of rows of the current query is returned. |
boolean |
setHeaderData(int section,
Qt.Orientation orientation,
java.lang.Object value,
int role)
Sets the caption for a horizontal header for the specified role to value. |
protected void |
setLastError(QSqlError error)
Protected function which allows derived classes to set the value of the last error that occurred on the database to error. |
void |
setQuery(QSqlQuery query)
Resets the model and sets the data provider to be the given query. |
void |
setQuery(java.lang.String query)
Equivalent to setQuery(query, QSqlDatabase()). |
void |
setQuery(java.lang.String query,
QSqlDatabase db)
Executes the query query for the given database connection db. |
Methods inherited from class com.trolltech.qt.gui.QAbstractTableModel |
---|
dropMimeData, hasChildren, index, parent |
Methods inherited from class com.trolltech.qt.core.QAbstractItemModel |
---|
beginInsertColumns, beginInsertRows, beginRemoveColumns, beginRemoveRows, buddy, changePersistentIndex, changePersistentIndexList, columnCount, createIndex, createIndex, createIndex, data, data, data, decodeData, encodeData, endInsertColumns, endInsertRows, endRemoveColumns, endRemoveRows, flags, hasChildren, hasIndex, hasIndex, headerData, index, insertColumn, insertColumn, insertColumns, insertRow, insertRow, insertRows, insertRows, itemData, match, match, match, match, mimeData, mimeTypes, persistentIndexList, removeColumn, removeColumn, removeColumns, removeRow, removeRow, removeRows, removeRows, reset, revert, rowCount, setData, setData, setData, setData, setHeaderData, setItemData, setSupportedDragActions, setSupportedDragActions, sibling, sort, sort, span, submit, supportedDragActions, supportedDropActions |
Methods inherited from class com.trolltech.qt.core.QObject |
---|
blockSignals, childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, property, removeEventFilter, setObjectName, setParent, setProperty, signalsBlocked, startTimer, thread, timerEvent |
Methods inherited from class com.trolltech.qt.QtJambiObject |
---|
dispose, disposed, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
---|
disconnect, disconnect, signalSender |
Methods inherited from class java.lang.Object |
---|
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
---|
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Constructor Detail |
---|
public QSqlQueryModel()
Equivalent to QSqlQueryModel(0).
public QSqlQueryModel(QObject parent)
Creates an empty QSqlQueryModel with the given parent.
Method Detail |
---|
protected QModelIndex indexInQuery(QModelIndex item)
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.
public final QSqlError lastError()
Returns information about the last error that occurred on the database.
public final QSqlQuery query()
Returns the QSqlQuery associated with this model.
public final QSqlRecord record()
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.
public final QSqlRecord record(int row)
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.
protected final void setLastError(QSqlError error)
Protected function which allows derived classes to set the value of the last error that occurred on the database to error.
public final void setQuery(java.lang.String query)
Equivalent to setQuery(query, QSqlDatabase()).
public final void setQuery(java.lang.String query, QSqlDatabase db)
Executes the query query for the given database connection 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:
QSqlQueryModel model; model.setQuery("select * from MyTable"); if (model.lastError().isValid()) qDebug() << model.lastError();
public void setQuery(QSqlQuery query)
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.
public boolean canFetchMore(QModelIndex parent)
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()).
parent should always be an invalid QModelIndex.
canFetchMore
in class QAbstractItemModel
public void clear()
Clears the model and releases any acquired resource.
public int columnCount(QModelIndex parent)
This function is reimplemented for internal reasons.
columnCount
in class QAbstractItemModel
public java.lang.Object data(QModelIndex item, int role)
Returns the value for the specified item and role.
If item is out of bounds or if an error occurred, an invalid QVariant is returned.
data
in class QAbstractItemModel
public void fetchMore(QModelIndex parent)
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:
while (myModel->canFetchMore()) myModel->fetchMore();
parent should always be an invalid QModelIndex.
fetchMore
in class QAbstractItemModel
public java.lang.Object headerData(int section, Qt.Orientation orientation, int role)
Returns the header data for the given role in the section of the header with the specified orientation.
headerData
in class QAbstractItemModel
public boolean insertColumns(int column, int count, QModelIndex parent)
Inserts count columns into the model at position column. The parent parameter must always be an invalid QModelIndex, since the model does not support parent-child relationships.
Returns true if 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:
QVariant MyModel::data(const QModelIndex &item, int role) const
{
if (item.column() == m_specialColumnNo) {
// handle column separately
}
return QSqlQueryModel::data(item, role);
}
insertColumns
in class QAbstractItemModel
protected void queryChange()
This virtual function is called whenever the query changes. The default implementation does nothing.
query returns the new query.
public boolean removeColumns(int column, int count, QModelIndex parent)
Removes count columns from the model starting from position column. The 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.
removeColumns
in class QAbstractItemModel
public int rowCount(QModelIndex parent)
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.
parent should always be an invalid QModelIndex.
rowCount
in class QAbstractItemModel
public boolean setHeaderData(int section, Qt.Orientation orientation, java.lang.Object value, int role)
Sets the caption for a horizontal header for the specified role to value. This is useful if the model is used to display data in a view (e.g., QTableView).
Returns true if orientation is Qt::Horizontal and the 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.
setHeaderData
in class QAbstractItemModel
public static QSqlQueryModel fromNativePointer(QNativePointer nativePointer)
nativePointer
- the QNativePointer of which object should be returned.
|
|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |