Detailed Description
The QSqlForm class creates and manages data entry forms
tied to SQL databases.
Typical use of a QSqlForm consists of the following steps:
- Create the widgets you want to appear in the form.
- Create a cursor and navigate to the record to be edited.
- Create the QSqlForm.
- Set the form's record buffer to the cursor's update buffer.
- Insert each widget and the field it is to edit into the form.
- Use readFields() to update the editor widgets with values from
the database's fields.
- Display the form and let the user edit values etc.
- Use writeFields() to update the database's field values with
the values in the editor widgets.
Note that a QSqlForm does not access the database directly, but
most often via QSqlFields which are part of a QSqlCursor. A
QSqlCursor::insert(), QSqlCursor::update() or QSqlCursor::del()
call is needed to actually write values to the database.
Some sample code to initialize a form successfully:
QLineEdit myEditor( this );
QSqlForm myForm( this );
QSqlCursor myCursor( "mytable" );
// Execute a query to make the cursor valid
myCursor.select();
// Move the cursor to a valid record (the first record)
myCursor.next();
// Set the form's record pointer to the cursor's edit buffer (which
// contains the current record's values)
myForm.setRecord( myCursor.primeUpdate() );
// Insert a field into the form that uses myEditor to edit the
// field 'somefield' in 'mytable'
myForm.insert( &myEditor, "somefield" );
// Update myEditor with the value from the mapped database field
myForm.readFields();
...
// Let the user edit the form
...
// Update the database
myForm.writeFields(); // Update the cursor's edit buffer from the form
myCursor.update(); // Update the database from the cursor's buffer
If you want to use custom editors for displaying and editing data
fields, you must install a custom QSqlPropertyMap. The form
uses this object to get or set the value of a widget.
Note that Qt Designer provides
a visual means of creating data-aware forms.
See also installPropertyMap(), QSqlPropertyMap, and Database Classes.
Member Function Documentation
QSqlForm::QSqlForm ( QObject * parent = 0, const char * name = 0 )
Constructs a QSqlForm with parent parent and called name.
QSqlForm::~QSqlForm ()
Destroys the object and frees any allocated resources.
void QSqlForm::clear () [virtual slot]
Removes every widget, and the fields they're mapped to, from the form.
void QSqlForm::clearValues ( bool nullify = FALSE ) [virtual slot]
Clears the values in all the widgets, and the fields they are
mapped to, in the form. If nullify is TRUE (the default is
FALSE), each field is also set to NULL.
uint QSqlForm::count () const
Returns the number of widgets in the form.
QWidget * QSqlForm::fieldToWidget ( QSqlField * field ) const
Returns the widget that field field is mapped to.
void QSqlForm::insert ( QWidget * widget, const QString & field ) [virtual]
Inserts a widget, and the name of the field it is to be
mapped to, into the form. To actually associate inserted widgets
with an edit buffer, use setRecord().
See also setRecord().
Examples: sql/overview/form1/main.cpp and sql/overview/form2/main.cpp.
void QSqlForm::insert ( QWidget * widget, QSqlField * field ) [virtual protected]
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
Inserts a widget, and the field it is to be mapped to, into
the form.
void QSqlForm::installPropertyMap ( QSqlPropertyMap * pmap )
Installs a custom QSqlPropertyMap. This is useful if you plan to
create your own custom editor widgets.
QSqlForm takes ownership of pmap, so pmap is deleted when
QSqlForm goes out of scope.
See also QDataTable::installEditorFactory().
Example: sql/overview/custom1/main.cpp.
void QSqlForm::readField ( QWidget * widget ) [virtual slot]
Updates the widget widget with the value from the SQL field it
is mapped to. Nothing happens if no SQL field is mapped to the widget.
void QSqlForm::readFields () [virtual slot]
Updates the widgets in the form with current values from the SQL
fields they are mapped to.
Examples: sql/overview/form1/main.cpp and sql/overview/form2/main.cpp.
void QSqlForm::remove ( QWidget * widget ) [virtual protected]
Removes a widget, and hence the field it's mapped to, from the
form.
void QSqlForm::remove ( const QString & field ) [virtual]
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
Removes field from the form.
void QSqlForm::setRecord ( QSqlRecord * buf ) [virtual]
Sets buf as the record buffer for the form. To force the
display of the data from buf, use readFields().
See also readFields() and writeFields().
Examples: sql/overview/custom1/main.cpp, sql/overview/form1/main.cpp, and sql/overview/form2/main.cpp.
QWidget * QSqlForm::widget ( uint i ) const
Returns the i-th widget in the form. Useful for traversing
the widgets in the form.
QSqlField * QSqlForm::widgetToField ( QWidget * widget ) const
Returns the SQL field that widget widget is mapped to.
void QSqlForm::writeField ( QWidget * widget ) [virtual slot]
Updates the SQL field with the value from the widget it is
mapped to. Nothing happens if no SQL field is mapped to the widget.
void QSqlForm::writeFields () [virtual slot]
Updates the SQL fields with values from the widgets they are
mapped to. To actually update the database with the contents of
the record buffer, use QSqlCursor::insert(), QSqlCursor::update()
or QSqlCursor::del() as appropriate.
Example: sql/overview/form2/main.cpp.
This file is part of the Qt toolkit.
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