Model/view system

Classes that implement Wt's model/view system. More...

Classes
struct	Wt::boost_any_traits< Type >
	A traits class for a type stored in a boost::any. More...
class	Wt::Chart::WAbstractChart
	Abstract base class for MVC-based charts. More...
class	Wt::Chart::WCartesianChart
	A cartesian chart. More...
class	Wt::Chart::WPieChart
	A pie chart. More...
class	Wt::Dbo::QueryModel< Result >
	A Wt MVC Model to view/edit query results. More...
class	Wt::Ext::ComboBox
	A widget that provides a drop-down combo-box control. More...
class	Wt::WAbstractItemDelegate
	Abstract delegate class for rendering an item in an item view. More...
class	Wt::WAbstractItemModel
	An abstract model for use with Wt's view classes. More...
class	Wt::WAbstractItemView
	An abstract base class for item Views. More...
class	Wt::WAbstractListModel
	An abstract list model for use with Wt's view classes. More...
class	Wt::WAbstractProxyModel
	An abstract proxy model for Wt's item models. More...
class	Wt::WAbstractTableModel
	An abstract table model for use with Wt's view classes. More...
class	Wt::WAggregateProxyModel
	A proxy model for Wt's item models that provides column aggregation. More...
class	Wt::WBatchEditProxyModel
	A proxy model for Wt's item models that provides batch editing. More...
class	Wt::WComboBox
	A widget that provides a drop-down combo-box control. More...
class	Wt::WItemDelegate
	Standard delegate class for rendering a view item. More...
class	Wt::WItemSelectionModel
	A class that represents a selection for a WAbstractItemView. More...
class	Wt::WModelIndex
	A value class that describes an index to an item in a data model. More...
class	Wt::WReadOnlyProxyModel
	A read-only wrapper for a source model. More...
class	Wt::WSelectionBox
	A selection box allows selection from a list of options. More...
class	Wt::WSortFilterProxyModel
	A proxy model for Wt's item models that provides filtering and/or sorting. More...
class	Wt::WStandardItem
	An item in a WStandardItemModel. More...
class	Wt::WStandardItemModel
	A standard data model, which stores its data in memory. More...
class	Wt::WStringListModel
	An model that manages a list of strings. More...
class	Wt::WSuggestionPopup
	A widget which popups to assist in editing a textarea or lineedit. More...
class	Wt::WTableView
	An MVC View widget for tabular data. More...
class	Wt::WTreeView
	A view class that displays a model as a tree or tree table. More...

Enumerations

Functions
WString	Wt::asString (const boost::any &v, const WString &formatString=WString())
	Interprets a boost::any as a string value. More...
double	Wt::asNumber (const boost::any &v)
	Interprets a boost::any as a number value. More...
template<typename Type >
void	Wt::registerType ()
	Registers MVC-support for a type passed in a boost::any. More...

Detailed Description

Classes that implement Wt's model/view system.

1. Models

The library provides support for tabular, tree-like and tree-table like models. All of these implement WAbstractItemModel.

Concrete model implementations

The following concrete model implementations are provided:

• Wt::WStandardItemModel: a full general purpose model, which stores data in memory.
• Wt::WStringListModel: a low-height single column model, useful for simple list views
• Wt::Dbo::QueryModel: a database query backed model

Proxy model implementations

Proxy models are helper models which wrap around another model, to provide additional functionality on top of the existing model. The following propy models:

• Wt::WSortFilterProxyModel: provides sorting and filtering support
• Wt::WAggregateProxyModel: provides column aggregation (useful only for views that implement column aggregation such as WAbstractItemView's).

Abstract models

Abstract models cannot be instantiated as such, but are the base point for custom model implementations:

• Wt::WAbstractItemModel: abstract base class of all models
• Wt::WAbstractTableModel: abstract base class for tabular models
• Wt::WAbstractProxyModel: abstract base class for proxy models.

2. Views

Item-based views

• WComboBox: a combo box
• WSelectionBox: a selection box
• WTableView: a table view (with editing support)
• WTreeView: a tree(-table) view (with editing support)
• WSuggestionPopup: an intelligent input-driven combo box

Graphical views

• Chart::WCartesianChart: 2D cartesian chart
• Chart::WPieChart: pie charts

ExtJS-based (JavaScript-only) views

These views are being deprecated in favour of accessible counterparts.

• Ext::ComboBox: ExtJS implementation of combo box
• Ext::TableView: ExtJS implementation of table view (with editing support)

3. Helper classes

Model indexes

WModelIndex represents an index to an item of a WAbstractItemModel, identified by a row, column and parent node.

Item delegates

Item delegates are used by WTableView and WTreeView to render a single item and to provide editing support.

The abstract base class is WAbstractItemDelegate, and a default implementation is provided by WItemDelegate.

Enumeration Type Documentation

enum Wt::DropAction

Enumeration that indicates a drop action.

See also

WAbstractItemModel::dropEvent()

Enumerator
CopyAction	Copy the selection.
MoveAction	Move the selection (deleting originals)

enum Wt::HeaderFlag

Flags that indicate table header options.

See also

WAbstractItemModel::headerFlags()

Enumerator
ColumnIsCollapsed	Flag that indicates that the column can be expanded. See also WAbstractItemModel::expandColumn()
ColumnIsExpandedLeft	Flag that indicates that the column was expanded to the left. See also WAbstractItemModel::collapseColumn()
ColumnIsExpandedRight	Flag that indicates that the column was expanded to the right. See also WAbstractItemModel::collapseColumn()
HeaderIsUserCheckable	Flag that indicates that the header can be checked.
HeaderIsTristate	Flag that indicates that the item has three states. When set, Wt::CheckStateRole data is of type Wt::CheckState
HeaderIsXHTMLText	Flag that indicates that the item text (DisplayRole, ToolTipRole) is HTML.

enum Wt::ItemDataRole

Enumeration that indicates a role for a data item.

A single data item can have data associated with it corresponding to different roles. Each role may be used by the corresponding view class in a different way.

See also

WModelIndex::data()

Enumerator
DisplayRole	Role for textual representation.
DecorationRole	Role for the url of an icon.
EditRole	Role for the edited value.
StyleClassRole	Role for the style class.
CheckStateRole	Role that indicates the check state. Data for this role should be a bool. When the Wt::ItemIsTristate flag is set for the item, data for this role should be of type Wt::CheckState.
ToolTipRole	Role for a (plain) tooltip.
LinkRole	Role for a link.
MimeTypeRole	Role for mime type information.
LevelRole	Level in aggregation, for header data.
MarkerPenColorRole	Marker pen color (for Chart::WCartesianChart)
MarkerBrushColorRole	Marker brush color (for Chart::WCartesianChart)
MarkerScaleFactorRole	Marker size (for Chart::WCartesianChart)
BarPenColorRole	Bar pen color (for Chart::WCartesianChart)
BarBrushColorRole	Bar brush color (for Chart::WCartesianChart)
UserRole	First role reserved for user purposes.

enum Wt::ItemFlag

Flags that indicate data item options.

See also

WModelIndex::flags()

Enumerator
ItemIsSelectable	Item can be selected.
ItemIsEditable	Item can be edited.
ItemIsUserCheckable	Item can be checked (checkbox is enabled)
ItemIsDragEnabled	Item can be dragged.
ItemIsDropEnabled	Item can be a drop target.
ItemIsTristate	Item has tree states. When set, Wt::CheckStateRole data is of type Wt::CheckState
ItemIsXHTMLText	Item's text (DisplayRole, ToolTipRole) is HTML.
ItemIsDirty	Item's value has been modified.
ItemHasDeferredTooltip	Item's tooltip is deferred.

enum Wt::MatchFlag

Flags that specify how to match two values.

Except when MatchExactly, the lexical matching is done (by comparing string representations of the value with the query). This is by default case insensitive, unless MatchCaseSensitive is OR'ed.

Enumerator
MatchExactly	Same type and value.
MatchStringExactly	Lexical match.
MatchStartsWith	Match start with query.
MatchEndsWith	Match end with query.
MatchRegExp	Regular expression match.
MatchWildCard	Wildcard match.
MatchCaseSensitive	Case sensitive.
MatchWrap	Wrap around whole model.

enum Wt::SortOrder

Enumeration that indicates a sort order.

Enumerator
AscendingOrder	Ascending sort order.
DescendingOrder	Descending sort order.

Function Documentation

double Wt::asNumber

(

const boost::any &

v

)

Interprets a boost::any as a number value.

The conversion works as follows:

• A boost::any without a value, or a string that does not represent a number, is converted to a NaN.
• A string is lexically casted to a double
• Data of type WDate is converted to an integer number using WDate::toJulianDay().
• Data of type WDateTime is converted to an integer number using WDateTime::toTime_t().
• Data of type WTime is converted to an integer number as the number of milliseconds since midnight.

Other types are converted according to Wt::boost_any_traits<Type>::asNumber(). For these other types, you need to register their support first using Wt::registerType<Type>() and you may want to specialize Wt::boost_any_traits<Type> for a custom handling of their conversions.

See also

asString(), boost_any_traits

WString Wt::asString	(	const boost::any &	v,
		const WString &	formatString = WString()
	)

Interprets a boost::any as a string value.

The conversion works as follows:

• A boost::any without a value is converted to an empty string
• Number values (integers and doubles) are formatted using the format string with snprintf(), or with boost::lexical_cast<> if the format string is empty.
• Data of type WDate is converted with WDate::toString() using the indicated format string. If the format string is empty, WLocalce::currentLocale().dateFormat() is assumed.
• Data of type WTime is converted with WTime::toString() using the indicated format string. If the format string is emtpy, WLocale::currentLocale().timeFormat() is assumed.
• Data of type WDateTime is converted with WDateTime::toString() using the indicated format string. If the format string is empty, WLocale::currentLocale().dateTimeFormat() is assumed.

Other types are converted according to Wt::boost_any_traits<Type>::asString(). For these other types, you need to register their support first using Wt::registerType<Type>() and you may want to specialize Wt::boost_any_traits<Type> for a custom handling of their conversions.

See also

asNumber(), boost_any_traits

template<typename Type >

void Wt::registerType

(

)

Registers MVC-support for a type passed in a boost::any.

By registering a type using this method, the global function Wt::asString(), which converts a boost::any to a string, will know how to interpret a boost::any holding a value of type Type using Wt::boost_any_traits<Type>::asString(). This gives Wt's built-in standard View classes the ability to display Wt::DisplayRole data of a Wt::WAbstractItemModel model.

Similarly, Wt::asNumber() uses Wt::boost_any_traits<Type>::asNumber() for use by Wt::Chart::WCartesianChart and Wt::Chart::WPieChart as numerical data.

The default implementation of Wt::boost_any_traits<Type> converts a value t to a Wt::WString by using boost::lexical_cast<std::string>() which it expects to return a UTF-8 string. This conversion thus relies on the std::ostream<< operator to be overloaded for the type. You may want to specialize Wt::boost_any_traits to provide a custom conversion for a type, or if you want to take into account the format string.

The following types are registered by Wt itself:

• strings of type WString or std::string
• WDate, WTime, WDateTime
• standard C++ numeric types (int, double, etc...)
• bool

This method is thread-safe, and it is not an error to register the same type multiple times.