The QQmlContext class defines a context within a QML engine. More...

#include <qqmlcontext.h>

Inheritance diagram for QQmlContext:

Collaboration diagram for QQmlContext:

Classes
class	PropertyPair

Public Member Functions
	QQmlContext (QQmlEngine parent, QObject objParent=nullptr)
	Create a new QQmlContext as a child of engine's root context, and the QObject parent.
	QQmlContext (QQmlContext parent, QObject objParent=nullptr)
	Create a new QQmlContext with the given parentContext, and the QObject parent.
	~QQmlContext () override
	Destroys the QQmlContext.
bool	isValid () const
	Returns whether the context is valid.
QQmlEngine *	engine () const
	Return the context's QQmlEngine, or \nullptr if the context has no QQmlEngine or the QQmlEngine was destroyed.
QQmlContext *	parentContext () const
	Return the context's parent QQmlContext, or \nullptr if this context has no parent or if the parent has been destroyed.
QList< QQmlContext * >	childContexts () const
QObject *	contextObject () const
	Return the context object, or \nullptr if there is no context object.
void	setContextObject (QObject *)
	Set the context object.
QVariant	contextProperty (const QString &) const
	Returns the value of the name property for this context as a QVariant.
void	setContextProperty (const QString &, QObject *)
	Set the value of the name property on this context.
void	setContextProperty (const QString &, const QVariant &)
	Set a the value of the name property on this context.
void	setContextProperties (const QList< PropertyPair > &properties)
QString	nameForObject (const QObject *) const
	Returns the name of object in this context, or an empty string if object is not named in the context.
QObject *	objectForName (const QString &) const
QObject *	findObjectRecursively (const QString &id) const
QList< QObject * >	findObjectsRecursively (const QString &id) const
QUrl	resolvedUrl (const QUrl &) const
	Resolves the URL src relative to the URL of the containing component.
void	setBaseUrl (const QUrl &)
	Explicitly sets the url resolvedUrl() will use for relative references to baseUrl.
QUrl	baseUrl () const
	Returns the base url of the component, or the containing component if none is set.
QJSValue	importedScript (const QString &name) const
Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.
virtual	~QObject ()
	Destroys the object, deleting all its child objects.
virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.
virtual bool	eventFilter (QObject watched, QEvent event)
	Filters events if this object has been installed as an event filter for the watched object.
QString	objectName () const
Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.
void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QBindable< QString >	bindableObjectName ()
bool	isWidgetType () const
	Returns `true` if the object is a widget; otherwise returns `false`.
bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.
bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.
bool	isQmlObjectType () const
	Returns whether the object has been created by the QML engine or ownership has been explicitly set via QJSEngine::setObjectOwnership().
bool	signalsBlocked () const noexcept
	Returns `true` if signals are blocked; otherwise returns `false`.
bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).
QThread *	thread () const
	Returns the thread in which the object lives.
bool	moveToThread (QThread *thread QT6_DECL_NEW_OVERLOAD_TAIL)
	Changes the thread affinity for this object and its children and returns `true` on success.
int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.
int	startTimer (std::chrono::nanoseconds time, Qt::TimerType timerType=Qt::CoarseTimer)
void	killTimer (int id)
	Kills the timer with timer identifier, id.
void	killTimer (Qt::TimerId id)
template<typename T>
T	findChild (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.
template<typename T>
QList< T >	findChildren (QAnyStringView aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.
template<typename T>
T	findChild (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
template<typename T>
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
const QObjectList &	children () const
	Returns a list of child objects.
void	setParent (QObject *parent)
	Makes the object a child of parent.
void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.
void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.
QMetaObject::Connection	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool	disconnect (const char signal=nullptr, const QObject receiver=nullptr, const char *member=nullptr) const
bool	disconnect (const QObject receiver, const char member=nullptr) const
void	dumpObjectTree () const
	Dumps a tree of children to the debug output.
void	dumpObjectInfo () const
	Dumps information about signal connections, etc.
bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.
bool	setProperty (const char *name, QVariant &&value)
QVariant	property (const char *name) const
	Returns the value of the object's name property.
QList< QByteArray >	dynamicPropertyNames () const
QBindingStorage *	bindingStorage ()
const QBindingStorage *	bindingStorage () const
QObject *	parent () const
	Returns a pointer to the parent object.
bool	inherits (const char *classname) const
	Returns `true` if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns `false`.

Friends
class	QQmlEngine
class	QQmlEnginePrivate
class	QQmlExpression
class	QQmlExpressionPrivate
class	QQmlComponent
class	QQmlComponentPrivate
class	QQmlScriptPrivate
class	QQmlContextData

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe
Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.
void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.
Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe
static QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1, typename Func2>
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)
template<typename Func1, typename Func2>
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)
static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	\threadsafe
static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)
static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.
template<typename Func1, typename Func2>
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)
template<typename Func1>
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)
Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.
int	senderSignalIndex () const
int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.
bool	isSignalConnected (const QMetaMethod &signal) const
virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.
virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.
virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.
virtual void	connectNotify (const QMetaMethod &signal)
virtual void	disconnectNotify (const QMetaMethod &signal)
	QObject (QObjectPrivate &dd, QObject *parent=nullptr)
Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr
Properties inherited from QObject
QString	objectName
	the name of this object
Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.
template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

The QQmlContext class defines a context within a QML engine.

\inmodule QtQml

Contexts hold the objects identified by id in a QML document. You can use \l{nameForObject()} and \l{objectForName()} to retrieve them.

Note: It is the responsibility of the creator to delete any QQmlContext it constructs. If a QQmlContext is no longer needed, it must be destroyed explicitly. The simplest way to ensure this is to give the QQmlContext a \l{QObject::setParent()}{parent}.

Definition at line 23 of file qqmlcontext.h.

Constructor & Destructor Documentation

◆ QQmlContext() [1/2]

QQmlContext::QQmlContext	(	QQmlEngine *	parent,
		QObject *	objParent = nullptr )

Create a new QQmlContext as a child of engine's root context, and the QObject parent.

Definition at line 99 of file qqmlcontext.cpp.

◆ QQmlContext() [2/2]

QQmlContext::QQmlContext	(	QQmlContext *	parent,
		QObject *	objParent = nullptr )

Create a new QQmlContext with the given parentContext, and the QObject parent.

Definition at line 110 of file qqmlcontext.cpp.

◆ ~QQmlContext()

QQmlContext::~QQmlContext ( )

override

Destroys the QQmlContext.

Any expressions, or sub-contexts dependent on this context will be invalidated, but not destroyed (unless they are parented to the QQmlContext object).

Definition at line 132 of file qqmlcontext.cpp.

Member Function Documentation

◆ baseUrl()

QUrl QQmlContext::baseUrl ( ) const

Returns the base url of the component, or the containing component if none is set.

Definition at line 533 of file qqmlcontext.cpp.

◆ childContexts()

QList< QQmlContext * > QQmlContext::childContexts ( ) const

Since: 6.11

Return the context's immediate child QQmlContexts.

See also: parentContext(), findObjectRecursively(), findObjectsRecursively()

Definition at line 180 of file qqmlcontext.cpp.

◆ contextObject()

QObject * QQmlContext::contextObject ( ) const

Return the context object, or \nullptr if there is no context object.

Definition at line 192 of file qqmlcontext.cpp.

◆ contextProperty()

QVariant QQmlContext::contextProperty ( const QString & name ) const

Returns the value of the name property for this context as a QVariant.

If you know that the property you're looking for is a QObject assigned using a QML id in the current context, \l objectForName() is more convenient and faster. In contrast to \l objectForName() and \l nameForObject(), this method does traverse the context hierarchy and searches in parent contexts if the name is not found in the current one. It also considers any \l contextObject() you may have set.

See also: objectForName(), nameForObject(), contextObject()

Definition at line 348 of file qqmlcontext.cpp.

◆ engine()

QQmlEngine * QQmlContext::engine ( ) const

Return the context's QQmlEngine, or \nullptr if the context has no QQmlEngine or the QQmlEngine was destroyed.

Definition at line 154 of file qqmlcontext.cpp.

◆ findObjectRecursively()

QObject * QQmlContext::findObjectRecursively ( const QString & id ) const

Since: 6.11

Searches this context and its children recursively for an object with ID id. If such an object is found, the object is returned. Otherwise returns \nullptr.

There can only be one object with the given id in any given context, but you can create many contexts within one document, for example with views and delegates. Each of those contexts can contain an object with the given id. Only the first one found is returned here. The search is conducted using breadth-first search.

See also: findObjectsRecursively(), objectForName(), childContexts()

Definition at line 449 of file qqmlcontext.cpp.

◆ findObjectsRecursively()

QList< QObject * > QQmlContext::findObjectsRecursively ( const QString & id ) const

Since: 6.11

Searches this context and its children recursively for objects with ID id. Returns a list of these objects.

There can only be one object with the given id in any given context, but you can create many contexts within one document, for example with views and delegates. Each of those contexts can contain an object with the given id.

See also: findObjectRecursively(), objectForName(), childContexts()

Definition at line 481 of file qqmlcontext.cpp.

◆ importedScript()

QJSValue QQmlContext::importedScript ( const QString & name ) const

Definition at line 542 of file qqmlcontext.cpp.

◆ isValid()

bool QQmlContext::isValid ( ) const

Returns whether the context is valid.

To be valid, a context must have a engine, and it's contextObject(), if any, must not have been deleted.

Definition at line 144 of file qqmlcontext.cpp.

◆ nameForObject()

QString QQmlContext::nameForObject ( const QObject * object ) const

Returns the name of object in this context, or an empty string if object is not named in the context.

Objects are named by \l setContextProperty(), or as properties of a context object, or by ids in the case of QML created contexts.

If the object has multiple names, the first is returned.

In contrast to \l contextProperty(), this method does not traverse the context hierarchy. If the name is not found in the current context, an empty String is returned.

See also: contextProperty(), objectForName()

Definition at line 388 of file qqmlcontext.cpp.

◆ objectForName()

QObject * QQmlContext::objectForName ( const QString & name ) const

Since: 6.2

Returns the object for a given name in this context. Returns nullptr if name is not available in the context or if the value associated with name is not a QObject. Objects are named by \l setContextProperty(), or as properties of a context object, or by ids in the case of QML created contexts. In contrast to \l contextProperty(), this method does not traverse the context hierarchy. If the name is not found in the current context, nullptr is returned.

See also: contextProperty(), nameForObject()

Definition at line 428 of file qqmlcontext.cpp.

◆ parentContext()

QQmlContext * QQmlContext::parentContext ( ) const

Return the context's parent QQmlContext, or \nullptr if this context has no parent or if the parent has been destroyed.

Definition at line 164 of file qqmlcontext.cpp.

◆ resolvedUrl()

QUrl QQmlContext::resolvedUrl ( const QUrl & src ) const

Resolves the URL src relative to the URL of the containing component.

See also: QQmlEngine::baseUrl(), setBaseUrl()

Definition at line 508 of file qqmlcontext.cpp.

◆ setBaseUrl()

void QQmlContext::setBaseUrl ( const QUrl & baseUrl )

Explicitly sets the url resolvedUrl() will use for relative references to baseUrl.

Calling this function will override the url of the containing component used by default.

See also: resolvedUrl()

Definition at line 522 of file qqmlcontext.cpp.

◆ setContextObject()

void QQmlContext::setContextObject ( QObject * object )

Set the context object.

Note: You should not use context objects to inject values into your QML components. Use singletons or regular object properties instead.

Definition at line 204 of file qqmlcontext.cpp.

◆ setContextProperties()

void QQmlContext::setContextProperties ( const QList< PropertyPair > & properties )

Since: 5.11

Set a batch of properties on this context.

Setting all properties in one batch avoids unnecessary refreshing expressions, and is therefore recommended instead of calling \l setContextProperty() for each individual property.

Note: You should not use context properties to inject values into your QML components. Use singletons or regular object properties instead.

See also: QQmlContext::setContextProperty()

Definition at line 297 of file qqmlcontext.cpp.

◆ setContextProperty() [1/2]

void QQmlContext::setContextProperty	(	const QString &	name,
		const QVariant &	value )

Set a the value of the name property on this context.

Note: You should not use context properties to inject values into your QML components. Use singletons or regular object properties instead.

Definition at line 230 of file qqmlcontext.cpp.

◆ setContextProperty() [2/2]

void QQmlContext::setContextProperty	(	const QString &	name,
		QObject *	value )

Set the value of the name property on this context.

QQmlContext does not take ownership of value.

Note: You should not use context properties to inject values into your QML components. Use singletons or regular object properties instead.

Definition at line 278 of file qqmlcontext.cpp.

◆ QQmlComponent

friend class QQmlComponent

friend

Definition at line 67 of file qqmlcontext.h.

◆ QQmlComponentPrivate

friend class QQmlComponentPrivate

friend

Definition at line 68 of file qqmlcontext.h.

◆ QQmlContextData

friend class QQmlContextData

friend

Definition at line 70 of file qqmlcontext.h.

◆ QQmlEngine

friend class QQmlEngine

friend

Definition at line 63 of file qqmlcontext.h.

◆ QQmlEnginePrivate

friend class QQmlEnginePrivate

friend

Definition at line 64 of file qqmlcontext.h.

◆ QQmlExpression

friend class QQmlExpression

friend

Definition at line 65 of file qqmlcontext.h.

◆ QQmlExpressionPrivate

friend class QQmlExpressionPrivate

friend

Definition at line 66 of file qqmlcontext.h.

◆ QQmlScriptPrivate

friend class QQmlScriptPrivate

friend

Definition at line 69 of file qqmlcontext.h.

The documentation for this class was generated from the following files:

qtdeclarative/src/qml/qml/qqmlcontext.h (bb9043bfbb2d08a95ad88c563124c52bf7a0c181)
qtdeclarative/src/qml/qml/qqmlcontext.cpp (bb9043bfbb2d08a95ad88c563124c52bf7a0c181)

Classes

Public Member Functions

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QQmlContext() [1/2]

◆ QQmlContext() [2/2]

◆ ~QQmlContext()

Member Function Documentation

◆ baseUrl()

◆ childContexts()

◆ contextObject()

◆ contextProperty()

◆ engine()

◆ findObjectRecursively()

◆ findObjectsRecursively()

◆ importedScript()

◆ isValid()

◆ nameForObject()

◆ objectForName()

◆ parentContext()

◆ resolvedUrl()

◆ setBaseUrl()

◆ setContextObject()

◆ setContextProperties()

◆ setContextProperty() [1/2]

◆ setContextProperty() [2/2]

Friends And Related Symbol Documentation

◆ QQmlComponent

◆ QQmlComponentPrivate

◆ QQmlContextData

◆ QQmlEngine

◆ QQmlEnginePrivate

◆ QQmlExpression

◆ QQmlExpressionPrivate

◆ QQmlScriptPrivate