QSqlForm Class

Qt 3.0.5

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QSqlForm Class Reference
[sql module]

The QSqlForm class creates and manages data entry forms tied to SQL databases. More...

#include <qsqlform.h>

Inherits QObject.

List of all member functions.

Public Members

Public Slots

Protected Members

  • virtual void insert ( QWidget * widget, QSqlField * field )
  • virtual void remove ( QWidget * widget )

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:

  1. Create the widgets you want to appear in the form.
  2. Create a cursor and navigate to the record to be edited.
  3. Create the QSqlForm.
  4. Set the form's record buffer to the cursor's update buffer.
  5. Insert each widget and the field it is to edit into the form.
  6. Use readFields() to update the editor widgets with values from the database's fields.
  7. Display the form and let the user edit values etc.
  8. 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/editing data fields, you need to 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 name 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, and pmap is therefore 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. Copyright © 1995-2002 Trolltech. All Rights Reserved.

Copyright © 2002 TrolltechTrademarks
Qt version 3.0.5

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