EntityTreeModel Class Reference

from PyKDE4.akonadi import *

Inherits: QAbstractItemModel → QObject
Namespace: Akonadi

Detailed Description

A model for collections and items together.

Akonadi models and views provide a high level way to interact with the akonadi server. Most applications will use these classes.

Models provide an interface for viewing, updating, deleting and moving Items and Collections. Additionally, the models are updated automatically if another application changes the data or inserts of deletes items etc.

Note:: The EntityTreeModel should be used with the EntityTreeView or the EntityListView class either directly or indirectly via proxy models.

<h3>Retrieving Collections and Items from the model</h3>

If you want to retrieve and Item or Collection from the model, and already have a valid QModelIndex for the correct row, the Collection can be retrieved like this:

 Collection col = index.data( EntityTreeModel.CollectionRole ).value<Collection>();

And similarly for Items. This works even if there is a proxy model between the calling code and the EntityTreeModel.

If you want to retrieve a Collection for a particular Collection.Id and you do not yet have a valid QModelIndex, use modelIndexForCollection.

<h3>Using EntityTreeModel in your application</h3>

The responsibilities which fall to the application developer are - Configuring the ChangeRecorder and EntityTreeModel - Making use of this class via proxy models - Subclassing for type specific display information

<h3>Creating and configuring the EntityTreeModel</h3>

This class is a wrapper around a Akonadi.ChangeRecorder object. The model represents a part of the collection and item tree configured in the ChangeRecorder. The structure of the model mirrors the structure of Collections and Items on the %Akonadi server.

The following code creates a model which fetches items and collections relevant to addressees (contacts), and automatically manages keeping the items up to date.


   ChangeRecorder *changeRecorder = new ChangeRecorder( this );
   changeRecorder->setCollectionMonitored( Collection.root() );
   changeRecorder->setMimeTypeMonitored( KABC.addresseeMimeType() );
   changeRecorder->setSession( session );

   EntityTreeModel *model = new EntityTreeModel( changeRecorder, this );

   EntityTreeView *view = new EntityTreeView( this );
   view->setModel( model );

The EntityTreeModel will show items of a different type by changing the line

 changeRecorder->setMimeTypeMonitored( KABC.addresseeMimeType() );

to a different mimetype. KABC.addresseeMimeType() is an alias for "text/directory". If changed to KMime.Message.mimeType() (an alias for "message/rfc822") the model would instead contain emails. The model can be configured to contain items of any mimetype known to %Akonadi.

Note:: The EntityTreeModel does some extra configuration on the Monitor, such as setting itemFetchScope() and collectionFetchScope() to retrieve all ancestors. This is necessary for proper function of the model.

See also:: Akonadi.ItemFetchScope.AncestorRetrieval.

See also:: akonadi-mimetypes.

The EntityTreeModel can be further configured for certain behaviours such as fetching of collections and items.

The model can be configured to not fetch items into the model (ie, fetch collections only) by setting

 entityTreeModel->setItemPopulationStrategy( EntityTreeModel.NoItemPopulation );

The items may be fetched lazily, i.e. not inserted into the model until request by the user for performance reasons.

The Collection tree is always built immediately if Collections are to be fetched.

 entityTreeModel->setItemPopulationStrategy( EntityTreeModel.LazyPopulation );

This will typically be used with a EntityMimeTypeFilterModel in a configuration such as KMail4.5 or AkonadiConsole.

The CollectionFetchStrategy determines how the model will be populated with Collections. That is, if FetchNoCollections is set, no collections beyond the root of the model will be fetched. This can be used in combination with setting a particular Collection to monitor.

 // Get an collection id from a config file.
 Collection.Id id;
 monitor->setCollectionMonitored( Collection( id ) );
 // ... Other initialization code.
 entityTree->setCollectionFetchStrategy( FetchNoCollections );

This has the effect of creating a model of only a list of Items, and not collections. This is similar in behaviour and aims to the ItemModel. By using FetchFirstLevelCollections instead, a mixed list of entities can be created.

Note:: It is important that you set only one Collection to be monitored in the monitor object. This one collection will be the root of the tree. If you need a model with a more complex structure, consider monitoring a common ancestor and using a SelectionProxyModel.

See also:: lazy-model-population

It is also possible to show the root Collection as part of the selectable model:

 entityTree->setIncludeRootCollection( true );

By default the displayed name of the root collection is '[*]', because it doesn't require i18n, and is generic. It can be changed too.

 entityTree->setIncludeRootCollection( true );
 entityTree->setRootCollectionDisplayName( i18nc( "Name of top level for all addressbooks in the application", "[All AddressBooks]" ) )

This feature is used in KAddressBook.

If items are to be fetched by the model, it is necessary to specify which parts of the items are to be fetched, using the ItemFetchScope class. By default, only the basic metadata is fetched. To fetch all item data, including all attributes:

 changeRecorder->itemFetchScope().fetchFullPayload();
 changeRecorder->itemFetchScope().fetchAllAttributes();

<h2>Using EntityTreeModel with Proxy models</h2>

An Akonadi.SelectionProxyModel can be used to simplify managing selection in one view through multiple proxy models to a representation in another view. The selectionModel of the initial view is used to create a proxied model which filters out anything not related to the current selection.

 // ... create an EntityTreeModel

 collectionTree = new EntityMimeTypeFilterModel( this );
 collectionTree->setSourceModel( entityTreeModel );

 // Include only collections in this proxy model.
 collectionTree->addMimeTypeInclusionFilter( Collection.mimeType() );
 collectionTree->setHeaderGroup( EntityTreeModel.CollectionTreeHeaders );

 treeview->setModel(collectionTree);

 // SelectionProxyModel can handle complex selections:
 treeview->setSelectionMode( QAbstractItemView.ExtendedSelection );

 SelectionProxyModel *selProxy = new SelectionProxyModel( treeview->selectionModel(), this );
 selProxy->setSourceModel( entityTreeModel );

 itemList = new EntityMimeTypeFilterModel( this );
 itemList->setSourceModel( selProxy );

 // Filter out collections. Show only items.
 itemList->addMimeTypeExclusionFilter( Collection.mimeType() );
 itemList->setHeaderGroup( EntityTreeModel.ItemListHeaders );

 EntityTreeView *itemView = new EntityTreeView( splitter );
 itemView->setModel( itemList );

The SelectionProxyModel can handle complex selections.

See the KSelectionProxyModel documentation for the valid configurations of a Akonadi.SelectionProxyModel.

Obviously, the SelectionProxyModel may be used in a view, or further processed with other proxy models. Typically, the result from this model will be further filtered to remove collections from the item list as in the above example.

There are several advantages of using EntityTreeModel with the SelectionProxyModel, namely the items can be fetched and cached instead of being fetched many times, and the chain of proxies from the core model to the view is automatically handled. There is no need to manage all the mapToSource and mapFromSource calls manually.

A KDescendantsProxyModel can be used to represent all descendants of a model as a flat list. For example, to show all descendant items in a selected Collection in a list:

 collectionTree = new EntityMimeTypeFilterModel( this );
 collectionTree->setSourceModel( entityTreeModel );

 // Include only collections in this proxy model.
 collectionTree->addMimeTypeInclusionFilter( Collection.mimeType() );
 collectionTree->setHeaderGroup( EntityTreeModel.CollectionTreeHeaders );

 treeview->setModel( collectionTree );

 SelectionProxyModel *selProxy = new SelectionProxyModel( treeview->selectionModel(), this );
 selProxy->setSourceModel( entityTreeModel );

 descendedList = new DescendantEntitiesProxyModel( this );
 descendedList->setSourceModel( selProxy );

 itemList = new EntityMimeTypeFilterModel( this );
 itemList->setSourceModel( descendedList );

 // Exclude collections from the list view.
 itemList->addMimeTypeExclusionFilter( Collection.mimeType() );
 itemList->setHeaderGroup( EntityTreeModel.ItemListHeaders );

 listView = new EntityTreeView( this );
 listView->setModel( itemList );

Note that it is important in this case to use the DescendantEntitesProxyModel before the EntityMimeTypeFilterModel. Otherwise, by filtering out the collections first, you would also be filtering out their child items.

This pattern is used in KAddressBook.

It would not make sense to use a KDescendantsProxyModel with LazyPopulation.

<h3>Subclassing EntityTreeModel</h3>

Usually an application will create a subclass of an EntityTreeModel and use that in several views via proxy models.

The subclassing is necessary in order for the data in the model to have type-specific representation in applications

For example, the headerData for an EntityTreeModel will be different depending on whether it is in a view showing only Collections in which case the header data should be "AddressBooks" for example, or only Items, in which case the headerData would be for example "Family Name", "Given Name" and "Email addres" for contacts or "Subject", "Sender", "Date" in the case of emails.

Additionally, the actual data shown in the rows of the model should be type specific.

In summary, it must be possible to have different numbers of columns, different data in hte rows of those columns, and different titles for each column depending on the contents of the view.

The way this is accomplished is by using the EntityMimeTypeFilterModel for splitting the model into a "CollectionTree" and an "Item List" as in the above example, and using a type-specific EntityTreeModel subclass to return the type-specific data, typically for only one type (for example, contacts or emails).

The following protected virtual methods should be implemented in the subclass: - int entityColumnCount( HeaderGroup headerGroup ) const; -- Implement to return the number of columns for a HeaderGroup. If the HeaderGroup is CollectionTreeHeaders, return the number of columns to display for the Collection tree, and if it is ItemListHeaders, return the number of columns to display for the item. In the case of addressee, this could be for example, two (for given name and family name) or for emails it could be three (for subject, sender, date). This is a decision of the subclass implementor. - QVariant entityHeaderData( int section, Qt.Orientation orientation, int role, HeaderGroup headerGroup ) const; -- Implement to return the data for each section for a HeaderGroup. For example, if the header group is CollectionTreeHeaders in a contacts model, the string "Address books" might be returned for column 0, whereas if the headerGroup is ItemListHeaders, the strings "Given Name", "Family Name", "Email Address" might be returned for the columns 0, 1, and 2. - QVariant entityData( const Collection &collection, int column, int role = Qt.DisplayRole ) const; -- Implement to return data for a particular Collection. Typically this will be the name of the collection or the EntityDisplayAttribute. - QVariant entityData( const Item &item, int column, int role = Qt.DisplayRole ) const; -- Implement to return the data for a particular item and column. In the case of email for example, this would be the actual subject, sender and date of the email.

Note:: The entityData methods are just for convenience. the QAbstractItemMOdel.data method can be overridden if required.

The application writer must then properly configure proxy models for the views, so that the correct data is shown in the correct view. That is the purpose of these lines in the above example

 collectionTree->setHeaderGroup( EntityTreeModel.CollectionTreeHeaders );
 itemList->setHeaderGroup( EntityTreeModel.ItemListHeaders );

<h3>Progress reporting</h3>

The EntityTreeModel uses asynchronous Akonadi.Job instances to fill and update itself. For example, a job is run to fetch the contents of collections (that is, list the items in it). Additionally, individual Akonadi.Items can be fetched in different parts at different times.

To indicate that such a job is underway, the EntityTreeModel makes the FetchState available. The FetchState returned from a QModelIndex representing a Akonadi.Collection will be FetchingState if a listing of the items in that collection is underway, otherwise the state is IdleState.

Author:: Stephen Kelly <steveire@gmail.com>

Since:: 4.4

Enumerations
CollectionFetchStrategy	{ FetchNoCollections, FetchFirstLevelChildCollections, FetchCollectionsRecursive, InvisibleCollectionFetch }
FetchState	{ IdleState, FetchingState }
HeaderGroup	{ EntityTreeHeaders, CollectionTreeHeaders, ItemListHeaders, UserHeaders, EndHeaderGroup }
ItemPopulationStrategy	{ NoItemPopulation, ImmediatePopulation, LazyPopulation }
Roles	{ ItemIdRole, ItemRole, MimeTypeRole, CollectionIdRole, CollectionRole, RemoteIdRole, CollectionChildOrderRole, AmazingCompletionRole, ParentCollectionRole, ColumnCountRole, LoadedPartsRole, AvailablePartsRole, SessionRole, CollectionRefRole, CollectionDerefRole, PendingCutRole, EntityUrlRole, UnreadCountRole, FetchStateRole, CollectionSyncProgressRole, UserRole, TerminalUserRole, EndRole }
Methods
	__init__ (self, Akonadi.ChangeRecorder monitor, QObject parent=0)
bool	canFetchMore (self, QModelIndex parent)
	clearAndReset (self)
Akonadi.EntityTreeModel.CollectionFetchStrategy	collectionFetchStrategy (self)
int	columnCount (self, QModelIndex parent=QModelIndex())
QVariant	data (self, QModelIndex index, int role=Qt.DisplayRole)
bool	dropMimeData (self, QMimeData data, Qt::DropAction action, int row, int column, QModelIndex parent)
int	entityColumnCount (self, Akonadi.EntityTreeModel.HeaderGroup headerGroup)
QVariant	entityData (self, Akonadi.Item item, int column, int role=Qt.DisplayRole)
QVariant	entityData (self, Akonadi.Collection collection, int column, int role=Qt.DisplayRole)
QVariant	entityHeaderData (self, int section, Qt::Orientation orientation, int role, Akonadi.EntityTreeModel.HeaderGroup headerGroup)
bool	entityMatch (self, Akonadi.Item item, QVariant value, Qt::MatchFlags flags)
bool	entityMatch (self, Akonadi.Collection collection, QVariant value, Qt::MatchFlags flags)
	fetchMore (self, QModelIndex parent)
Qt::ItemFlags	flags (self, QModelIndex index)
bool	hasChildren (self, QModelIndex parent=QModelIndex())
QVariant	headerData (self, int section, Qt::Orientation orientation, int role=Qt.DisplayRole)
bool	includeRootCollection (self)
bool	includeUnsubscribed (self)
QModelIndex	index (self, int row, int column, QModelIndex parent=QModelIndex())
Akonadi.EntityTreeModel.ItemPopulationStrategy	itemPopulationStrategy (self)
[QModelIndex]	match (self, QModelIndex start, int role, QVariant value, int hits=1, Qt::MatchFlags flags=Qt.MatchFlags(Qt.MatchStartsWith\|Qt.MatchWrap))
QMimeData	mimeData (self, [QModelIndex] indexes)
QStringList	mimeTypes (self)
QModelIndex	parent (self, QModelIndex index)
QString	rootCollectionDisplayName (self)
int	rowCount (self, QModelIndex parent=QModelIndex())
	setCollectionFetchStrategy (self, Akonadi.EntityTreeModel.CollectionFetchStrategy strategy)
bool	setData (self, QModelIndex index, QVariant value, int role=Qt.EditRole)
	setIncludeRootCollection (self, bool include)
	setIncludeUnsubscribed (self, bool show)
	setItemPopulationStrategy (self, Akonadi.EntityTreeModel.ItemPopulationStrategy strategy)
	setRootCollectionDisplayName (self, QString name)
	setShowSystemEntities (self, bool show)
Qt::DropActions	supportedDropActions (self)
bool	systemEntitiesShown (self)
Static Methods
QModelIndex	modelIndexForCollection (QAbstractItemModel model, Akonadi.Collection collection)
[QModelIndex]	modelIndexesForItem (QAbstractItemModel model, Akonadi.Item item)

Method Documentation

__init__	(	self,
		Akonadi.ChangeRecorder	monitor,
		QObject	parent=0
	)

Creates a new entity tree model.

Parameters:

	monitor	The ChangeRecorder whose entities should be represented in the model.
	parent	The parent object.

bool canFetchMore	(	self,
		QModelIndex	parent
	)

clearAndReset ( self )

Clears and resets the model. Always call this instead of the reset method in the superclass. Using the reset method will not reliably clear or refill the model.

Akonadi.EntityTreeModel.CollectionFetchStrategy collectionFetchStrategy ( self )

Returns the collection fetch strategy of the model.

int columnCount	(	self,
		QModelIndex	parent=QModelIndex()
	)

QVariant data	(	self,
		QModelIndex	index,
		int	role=Qt.DisplayRole
	)

bool dropMimeData	(	self,
		QMimeData	data,
		Qt::DropAction	action,
		int	row,
		int	column,
		QModelIndex	parent
	)

int entityColumnCount	(	self,
		Akonadi.EntityTreeModel.HeaderGroup	headerGroup
	)

QVariant entityData	(	self,
		Akonadi.Item	item,
		int	column,
		int	role=Qt.DisplayRole
	)

Provided for convenience of subclasses.

QVariant entityData	(	self,
		Akonadi.Collection	collection,
		int	column,
		int	role=Qt.DisplayRole
	)

Provided for convenience of subclasses.

QVariant entityHeaderData	(	self,
		int	section,
		Qt::Orientation	orientation,
		int	role,
		Akonadi.EntityTreeModel.HeaderGroup	headerGroup
	)

Reimplement this to provide different header data. This is needed when using one model with multiple proxies and views, and each should show different header data.

bool entityMatch	(	self,
		Akonadi.Item	item,
		QVariant	value,
		Qt::MatchFlags	flags
	)

Reimplement this in a subclass to return true if collection matches value with flags in the AmazingCompletionRole.

bool entityMatch	(	self,
		Akonadi.Collection	collection,
		QVariant	value,
		Qt::MatchFlags	flags
	)

Reimplement this in a subclass to return true if collection matches value with flags in the AmazingCompletionRole.

fetchMore	(	self,
		QModelIndex	parent
	)

Qt::ItemFlags flags	(	self,
		QModelIndex	index
	)

bool hasChildren	(	self,
		QModelIndex	parent=QModelIndex()
	)

QVariant headerData	(	self,
		int	section,
		Qt::Orientation	orientation,
		int	role=Qt.DisplayRole
	)

bool includeRootCollection ( self )

Returns whether the root collection is provided by the model.

bool includeUnsubscribed ( self )

Returns whether unsubscribed entities will be included in the listing.

Since:: 4.5

QModelIndex index	(	self,
		int	row,
		int	column,
		QModelIndex	parent=QModelIndex()
	)

Akonadi.EntityTreeModel.ItemPopulationStrategy itemPopulationStrategy ( self )

Returns the item population strategy of the model.

[QModelIndex] match	(	self,
		QModelIndex	start,
		int	role,
		QVariant	value,
		int	hits=1,
		Qt::MatchFlags	flags=Qt.MatchFlags(Qt.MatchStartsWith\|Qt.MatchWrap)
	)

Reimplemented to handle the AmazingCompletionRole.

QMimeData mimeData	(	self,
		[QModelIndex]	indexes
	)

QStringList mimeTypes ( self )

QModelIndex parent	(	self,
		QModelIndex	index
	)

QString rootCollectionDisplayName ( self )

Returns the display name of the root collection.

int rowCount	(	self,
		QModelIndex	parent=QModelIndex()
	)

setCollectionFetchStrategy	(	self,
		Akonadi.EntityTreeModel.CollectionFetchStrategy	strategy
	)

Sets the collection fetch strategy of the model.

bool setData	(	self,
		QModelIndex	index,
		QVariant	value,
		int	role=Qt.EditRole
	)

setIncludeRootCollection	(	self,
		bool	include
	)

Sets whether the root collection shall be provided by the model.

See also:: setRootCollectionDisplayName()

setIncludeUnsubscribed	(	self,
		bool	show
	)

Sets whether unsubscribed entities will be included in the listing. By default it's true

Note that it is possible to change the monitor's fetchscope directly, bypassing this method, which will lead to inconsistencies. Use this method for turning on/off listing of subscribed folders.

Since:: 4.5

setItemPopulationStrategy	(	self,
		Akonadi.EntityTreeModel.ItemPopulationStrategy	strategy
	)

Sets the item population strategy of the model.

setRootCollectionDisplayName	(	self,
		QString	name
	)

Sets the display name of the root collection of the model. The default display name is "[*]".

Note:: The display name for the root collection is only used if the root collection has been included with setIncludeRootCollection().

setShowSystemEntities	(	self,
		bool	show
	)

Some Entities are hidden in the model, but exist for internal purposes, for example, custom object directories in groupware resources.

They are hidden by default, but can be shown by setting show to true.

Most applications will not need to use this feature.

Qt::DropActions supportedDropActions ( self )

bool systemEntitiesShown ( self )

Returns true if internal system entities are shown, and false otherwise.

Static Method Documentation

QModelIndex modelIndexForCollection	(	QAbstractItemModel	model,
		Akonadi.Collection	collection
	)

Returns a QModelIndex in model which points to collection. This method can be used through proxy models if model is a proxy model.

 EntityTreeModel *model = getEntityTreeModel();
 QSortFilterProxyModel *proxy1 = new QSortFilterProxyModel;
 proxy1->setSourceModel(model);
 QSortFilterProxyModel *proxy2 = new QSortFilterProxyModel;
 proxy2->setSourceModel(proxy1);

 ...

 QModelIndex idx = EntityTreeModel.modelIndexForCollection(proxy2, Collection(colId));
 if (!idx.isValid())
   // Collection with id colId is not in the proxy2.
   // Maybe it is filtered out if proxy 2 is only showing items? Make sure you use the correct proxy.
   return;

 Collection collection = idx.data( EntityTreeModel.CollectionRole ).value<Collection>();
 // collection has the id colId, and all other attributes already fetched by the model such as name, remoteId, Akonadi.Attributes etc.

This can be useful for example if an id is stored in a config file and needs to be used in the application.

Note however, that to restore view state such as scrolling, selection and expansion of items in trees, the ETMViewStateSaver can be used for convenience.

See also:: modelIndexesForItem

Since:: 4.5

[QModelIndex] modelIndexesForItem	(	QAbstractItemModel	model,
		Akonadi.Item	item
	)

Returns a QModelIndex in model which points to item. This method can be used through proxy models if model is a proxy model.

See also:: modelIndexForCollection

Since:: 4.5

Enumeration Documentation

CollectionFetchStrategy

Describes what collections shall be fetched by and represent in the model.

Enumerator:

FetchNoCollections
FetchFirstLevelChildCollections
FetchCollectionsRecursive
InvisibleCollectionFetch

FetchState

Describes the state of fetch jobs related to particular collections.

   QModelIndex collectionIndex = getIndex();
   if (collectionIndex.data(EntityTreeModel.FetchStateRole).toLongLong() == FetchingState) {
     // There is a fetch underway
   } else {
     // There is no fetch underway.
   }

Since:: 4.5

Enumerator:

IdleState
FetchingState

HeaderGroup

Describes what header information the model shall return.

Enumerator:

EntityTreeHeaders
CollectionTreeHeaders
ItemListHeaders
UserHeaders = 10
EndHeaderGroup = 32

ItemPopulationStrategy

Describes how the model should populated its items.

Enumerator:

NoItemPopulation
ImmediatePopulation
LazyPopulation

Roles

Describes the roles for items. Roles for collections are defined by the superclass.

Enumerator:

IdRole = Qt::UserRole+1
ItemRole
MimeTypeRole
UserRole = Qt::UserRole+42

EntityTreeModel Class Reference

Detailed Description

Enumerations

Methods

Static Methods

Method Documentation

Static Method Documentation

Enumeration Documentation

Modules