QListDataModel

Since: BlackBerry 10.0.0

#include <bb/cascades/QListDataModel>

Contains a list of <Item> values, typically for a ListView.

The templated QListDataModel Model class implements the abstract DataModel class.

Template class <Item> must be convertible to QVariant in order for the data() function to work. To accomplish that, use the Q_DECLARE_METATYPE macro. For example:

 namespace mynamespace {
 class Contact {
 ...
 }
 } // mynamespace
 Q_DECLARE_METATYPE( mynamespace::Contact *);

Then the custom object (pointer to Contact) would become convertible to and from QVariant: 

 Contact *pCnt1 = new Contact();
 QVariant q = QVariant::fromValue(pCnt1);
 Contact *pCnt2 = q.value<Contact*>();

And usable in the model: QListDataModel<Contact *> contactsModel;

Similarly, Contacts objects (not pointers) can be declared and stored in the model.

As a convenience, QListDataModel includes the following typedefs: QVariantListDataModel, QStringListDataModel, and QMapListDataModel. For more information about these typedefs, see bb::cascades.

See also:

ListView, DataModel

Overview

Inheritance

bb::cascades::DataModel
bb::cascades::QListDataModel

Public Functions Index

QListDataModel ()
QListDataModel (const QList< Item > &other)
virtual ~QListDataModel ()
voidappend (const Item &value)
voidappend (const QList< Item > &values)
virtual intchildCount (const QVariantList &indexPath)
voidclear ()
virtual QVariantdata (const QVariantList &indexPath)
virtual boolhasChildren (const QVariantList &indexPath)
intindexOf (const Item &value, int from=0) const
voidinsert (int i, const Item &value)
voidinsert (int i, const QList< Item > &values)
boolisEmpty () const
virtual QStringitemType (const QVariantList &indexPath)
voidmove (int from, int to)
QListDataModel &operator<< (const Item &value)
voidremoveAt (int i)
voidreplace (int i, const Item &value)
intsize () const
voidswap (int i, int j)
Itemvalue (int i) const
Itemvalue (int i, const Item &defaultValue) const
DataModel (QObject *parent=0)Inherited

Signals Index

Only has inherited signals

voiditemAdded (QVariantList indexPath)Inherited
voiditemMoved (QVariantList fromIndexPath, QVariantList toIndexPath)Inherited
voiditemRemoved (QVariantList indexPath)Inherited
voiditemsChanged (bb::cascades::DataModelChangeType::Type eChangeType=bb::cascades::DataModelChangeType::Init, QSharedPointer< bb::cascades::DataModel::IndexMapper > indexMapper=QSharedPointer< bb::cascades::DataModel::IndexMapper >(0))Inherited
voiditemUpdated (QVariantList indexPath)Inherited

Public Functions

QListDataModel ()

Constructs an empty QListDataModel.

Since:

BlackBerry 10.0.0

QListDataModel (
  • const QList< Item > &other)

Constructs a QListDataModel holding the provided QVariantList.

Ownership of the specified QVariantList is transferred to this QListDataModel.

Parameters
other

The initial data to be used by this QListDataModel.
Since:

BlackBerry 10.0.0

virtual~QListDataModel ()

Destructor.

void append (
  • const Item &value)

Inserts the specified value at the end of this model.

The value must be convertible to a QVariant.

Parameters
value

The value to be appended. Ownership of QObject items that don't have parents is transferred to this QListDataModel.
Since:

BlackBerry 10.0.0

void append (
  • const QList< Item > &values)

Inserts the specified list of values at the end of this QListDataModel.

Each Item in the list must be convertible to a QVariant.

Parameters
values

The list of QVariant items to be appended. Ownership of QObject items that don't have parents is transferred to this QListDataModel.
Since:

BlackBerry 10.0.0

virtual int childCount (

Returns the number of children to the data item specified by indexPath.

Parameters
indexPath

The index path to the data item to get child count for.
Return:

The number of children.

Since:

BlackBerry 10.0.0

Since:

BlackBerry 10.0.0

void clear ()

Removes all values from this model.

QObjects owned by this model are deleted.

Since:

BlackBerry 10.0.0

virtualQVariant data (

Returns the data item that is associated with indexPath.

This function transfers ownership for QObject objects, if the returned object doesn't have any parent.

The ListView will pass the data item as a parameter to ListItemProvider::updateItem(). If item visuals are created by using ListItemComponent in QML, ListView makes the data returned from this function available in the item visuals as the context property ListItemData, and also as the property ListItem.data attached to the item visual root node.

Parameters
indexPath

The index path to the data item.
Return:

The data item associated with the indexPath. The caller must take ownership of any returned QObject objects, if the returned object doesn't already have a parent.

See also:

ListItemProvider

Since:

BlackBerry 10.0.0

Since:

BlackBerry 10.0.0

virtual bool hasChildren (

Indicates whether the data item specified by indexPath has children.

ListView never calls this function for its root node (but does call childCount(QVariantList) for the root node), so if this DataModel only contains one level of items (no child items), this function can always return false.

Here's an example of how to override hasChildren().

 bool SmartViewModel::hasChildren(const QVariantList &indexPath)
 {
     // Checks whether the indexPath is an empty array.
     // An empty array indicates the the index path is for the
     // root element.
     if(indexPath.empty())
         return true; // The root node always has children

     // ...Check for other index paths...
 }
Parameters
indexPath

The index path to the data item to query for children.
Return:

true if the data item has one or more children, false otherwise.

Since:

BlackBerry 10.0.0

Since:

BlackBerry 10.0.0

int indexOf (
  • const Item &value,
  • intfrom )

Searches this QListDataModel from the specified index position from until the specified item is found.

If no such item is found, -1 is returned.

Parameters
value

The QVariant to search for.

from

The index position to search from.
Return:

The index position if a matching item was found, -1 otherwise.

Since:

BlackBerry 10.0.0

void insert (
  • inti,
  • const Item &value )

Inserts a single QVariant value at the specified index position i in this QListDataModel.

If i is 0, the value is prepended to the list. If i is size(), the value is appended to the list.

Parameters
i

The position in this QListDataModel to add the value.

value

The QVariant value to be inserted. Ownership of QObject items that don't have parents is transferred to this QListDataModel.
Since:

BlackBerry 10.0.0

void insert (
  • inti,
  • const QList< Item > &values )

Inserts a list of QVariant values at the specified index position i in this QListDataModel.

If i is 0, the values are prepended to the list. If i is size(), the values are appended to the list.

Parameters
i

The position in this QListDataModel to add the list of values.

values

The list of QVariant items to be inserted. Ownership of QObject items that don't have parents is transferred to this QListDataModel.
Since:

BlackBerry 10.0.0

bool isEmpty ()

Indicates whether this QListDataModel is empty.

Return:

true if the model holds no values, false otherwise.

Since:

BlackBerry 10.0.0

virtualQString itemType (

Returns the item type for the data item at indexPath.

The item type will then be used when the ListView requests items from its ListItemProvider. It will also be used when the DataModel has indicated that items have been updated using the signals DataModel::itemUpdated or DataModel::itemsChanged with DataModelChangeType::Update.

If a ListItemTypeMapper has been provided to a ListView, the ListView calls ListItemTypeMapper::itemType() instead of DataModel::itemType().

Parameters
indexPath

The index path to the data item.
Return:

A string representing the user-defined type of the item. The default implementation returns an empty string.

Since:

BlackBerry 10.0.0

Since:

BlackBerry 10.0.0

void move (
  • intfrom,
  • intto )

Moves the value at index position from to index position to.

This assumes that both from and to are at least 0 and less than size().

Parameters
from

Index position to move from.

to

Index position to move to.
Since:

BlackBerry 10.0.0

QListDataModel & operator<< (
  • const Item &value)

Appends the specified value to the QListDataModel and returns a reference to the QListDataModel.

Parameters
value

The value to be appended. Ownership of QObject items that don't have parents is transferred to this QListDataModel.
Return:

A reference to the QListDataModel.

Since:

BlackBerry 10.0.0

void removeAt (
  • inti)

Removes the value at index position i.

i must be at least 0 and less than size(). QObjects owned by the model are deleted.

Parameters
i

Index of value to be removed.
Since:

BlackBerry 10.0.0

void replace (
  • inti,
  • const Item &value )

Replaces the value at index position i with value.

If the old value is owned by QListDataModel, it will be deleted.

i must be at least 0 and less than size().

Parameters
i

Index of value to be replaced.

value

Replacement value. Ownership of parentless QObjects is transferred to QListDataModel.
Since:

BlackBerry 10.0.0

int size ()

Returns the number of values in the QListDataModel.

Return:

Number of values in the QListDataModel.

Since:

BlackBerry 10.0.0

void swap (
  • inti,
  • intj )

Exchange the value at index position i with the value at index position j.

The function assumes that both i and j are at least 0 and less than size().

Parameters
i

Index of first value.

j

Index of second value.
Since:

BlackBerry 10.0.0

Item value (
  • inti)

Returns the value at index position i in the QListIndexModel.

If index i is out of bounds, the function returns a default-constructed value.

Parameters
i

Index of value to be returned.

Return:

Value at index position i.

Since:

BlackBerry 10.0.0

Item value (
  • inti,
  • const Item &defaultValue )

Returns the value at index position i in the QListIndexModel.

If index i is not at least 0 and less than size(), the function returns defaultValue.

Parameters
i

Index of value to be returned.

defaultValue

Value to be returned if i is out of bounds.

Return:

Value at index position i.

Since:

BlackBerry 10.0.0

DataModel (Inherited

Constructs a DataModel instance with the specified parent.

Parameters
parent

The data model owner, or 0. Optional and will default to 0 if not specified.
Since:

BlackBerry 10.0.0

Signals

(Only has inherited signals)

void itemAdded (Inherited

Emitted when a data item has been added to this DataModel.

Parameters
indexPath

The index path to the new item.
Since:

BlackBerry 10.0.0

void itemMoved (Inherited

Emitted when a data item has been moved within the DataModel.

A moved item will retain its visual appearance and data on the server.

Parameters
fromIndexPath

The original index path of the moved item.

toIndexPath

The new index path of the moved item.
Since:

BlackBerry 10.3.0

void itemRemoved (Inherited

Emitted when a data item has been removed from this DataModel.

Parameters
indexPath

The index path to the removed item.
Since:

BlackBerry 10.0.0

void itemsChanged (Inherited

Emitted when the model has changed in a way that would be inefficient to describe with single instances of the other signals.

No other signals (DataModel::itemAdded, DataModel::itemUpdated, or DataModel::itemRemoved) are emitted if this signal is emitted when a change occurs in this DataModel.

Typical examples of when this signal is emitted: data has been sorted (so that many items have changed places), the DataModel has been cleared (all items have been removed), or a batch of items has been added.

If eChangeType is DataModelChangeType::Init, or if eChangeType is DataModelChangeType::AddRemove and indexMapper is 0, a ListView reacts to this signal by releasing all of the items in its cache.

If eChangeType is AddRemove and an IndexMapper is provided, the ListView instead calls IndexMapper::newIndexPath() for each item in its cache.

If eChangeType is DataModelChangeType::Update, a ListView reacts to this signal by calling DataModel::data() again for every item in its cache.

Parameters
eChangeType

The type of change.

indexMapper

An index mapper that contains update information.
Since:

BlackBerry 10.0.0

void itemUpdated (Inherited

Emitted when a data item in this DataModel has been updated.

Parameters
indexPath

IndexPath to the updated item.
Since:

BlackBerry 10.0.0

Last modified: 2015-01-22



Got questions about leaving a comment? Get answers from our Disqus FAQ.

comments powered by Disqus