The QQmlListReference class allows the manipulation of QQmlListProperty properties. More...

#include <qqmllist.h>

Collaboration diagram for QQmlListReference:

Public Member Functions
	QQmlListReference ()
	Constructs an invalid instance.

	QQmlListReference (const QVariant &variant)

	QQmlListReference (QObject o, const char property)
	Constructs a QQmlListReference for object's property.

	QQmlListReference (const QQmlListReference &)

QQmlListReference &	operator= (const QQmlListReference &)

	~QQmlListReference ()

bool	isValid () const
	Returns true if the instance refers to a valid list property, otherwise false.

QObject *	object () const
	Returns the list property's object.

const QMetaObject *	listElementType () const
	Returns the QMetaObject for the elements stored in the list property, or \nullptr if the reference is invalid.

bool	canAppend () const
	Returns true if the list property can be appended to, otherwise false.

bool	canAt () const
	Returns true if the list property can queried by index, otherwise false.

bool	canClear () const
	Returns true if the list property can be cleared, otherwise false.

bool	canCount () const
	Returns true if the list property can be queried for its element count, otherwise false.

bool	canReplace () const
	Returns true if items in the list property can be replaced, otherwise false.

bool	canRemoveLast () const
	Returns true if the last item can be removed from the list property, otherwise false.

bool	isManipulable () const
	Return true if at(), count(), append(), and either clear() or removeLast() are implemented, so you can manipulate the list.

bool	isReadable () const
	Return true if at() and count() are implemented, so you can access the elements.

bool	append (QObject *) const
	Appends object to the list.

QObject *	at (qsizetype) const
	Returns the list element at index, or 0 if the operation failed.

bool	clear () const
	Clears the list.

qsizetype	count () const
	Returns the number of objects in the list, or 0 if the operation failed.

qsizetype	size () const

bool	replace (qsizetype, QObject *) const
	Replaces the item at index in the list with object.

bool	removeLast () const
	Removes the last item in the list.

bool	operator== (const QQmlListReference &other) const
	Compares this QQmlListReference to other, and returns `true` if they are equal.

Friends
class	QQmlListReferencePrivate

Detailed Description

The QQmlListReference class allows the manipulation of QQmlListProperty properties.

Since: 5.0 \inmodule QtQml

QQmlListReference allows C++ programs to read from, and assign values to a QML list property in a simple and type-safe way. A QQmlListReference can be created by passing an object and property name or through a QQmlProperty instance. These two are equivalent:

QQmlListReference ref1(object, "children");
 
QQmlProperty ref2(object, "children");
QQmlListReference ref2 = qvariant_cast<QQmlListReference>(ref2.read());

Not all QML list properties support all operations. A set of methods, canAppend(), canAt(), canClear() and canCount() allow programs to query whether an operation is supported on a given property.

QML list properties are type-safe. Only QObject's that derive from the correct base class can be assigned to the list. The listElementType() method can be used to query the QMetaObject of the QObject type supported. Attempting to add objects of the incorrect type to a list property will fail.

Like with normal lists, when accessing a list element by index, it is the callers responsibility to ensure that it does not request an out of range element using the count() method before calling at().

Definition at line 182 of file qqmllist.h.

Constructor & Destructor Documentation

◆ QQmlListReference() [1/4]

QQmlListReference::QQmlListReference ( )

Constructs an invalid instance.

Definition at line 85 of file qqmllist.cpp.

◆ QQmlListReference() [2/4]

QQmlListReference::QQmlListReference ( const QVariant & variant )

explicit

Since: 6.1

Constructs a QQmlListReference from a QVariant variant containing a QQmlListProperty. If variant does not contain a list property, an invalid QQmlListReference is created. If the object owning the list property is destroyed after the reference is constructed, it will automatically become invalid. That is, it is safe to hold QQmlListReference instances even after the object is deleted.

Definition at line 132 of file qqmllist.cpp.

◆ QQmlListReference() [3/4]

QQmlListReference::QQmlListReference	(	QObject *	object,
		const char *	property )

Constructs a QQmlListReference for object's property.

If property is not a list property, an invalid QQmlListReference is created. If object is destroyed after the reference is constructed, it will automatically become invalid. That is, it is safe to hold QQmlListReference instances even after object is deleted.

Definition at line 154 of file qqmllist.cpp.

◆ QQmlListReference() [4/4]

QQmlListReference::QQmlListReference ( const QQmlListReference & o )

Definition at line 174 of file qqmllist.cpp.

◆ ~QQmlListReference()

QQmlListReference::~QQmlListReference ( )

Definition at line 190 of file qqmllist.cpp.

Member Function Documentation

◆ append()

bool QQmlListReference::append ( QObject * object ) const

Appends object to the list.

Returns true if the operation succeeded, otherwise false.

See also: canAppend()

Definition at line 326 of file qqmllist.cpp.

◆ at()

QObject * QQmlListReference::at ( qsizetype index ) const

Returns the list element at index, or 0 if the operation failed.

See also: canAt()

Definition at line 343 of file qqmllist.cpp.