class QWebChannel

Exposes QObjects to remote HTML clients. More…

Inheritance diagram of PySide6.QtWebChannel.QWebChannel

Synopsis

Properties

Methods

Slots

Signals

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description

The QWebChannel fills the gap between C++ applications and HTML/JavaScript applications. By publishing a QObject derived object to a QWebChannel and using the qwebchannel.js on the HTML side, one can transparently access properties and public slots and methods of the QObject. No manual message passing and serialization of data is required, property updates and signal emission on the C++ side get automatically transmitted to the potentially remotely running HTML clients. On the client side, a JavaScript object will be created for any published C++ QObject. It mirrors the C++ object’s API and thus is intuitively useable.

QWebChannel transparently supports QFuture. When a client calls a method that returns a QFuture, QWebChannel will send a response with the QFuture result only after the QFuture has finished.

Custom conversion of types to and from JSON is supported by defining converters with QMetaType::registerConverter() to and from QJsonValue. Note that custom converters from QJsonValue to a concrete type must fail if the QJsonValue does not match the expected format. Otherwise QWebChannel cannot fall back to its default conversion mechanisms. Custom converters are also available on the JavaScript side .

The C++ QWebChannel API makes it possible to talk to any HTML client, which could run on a local or even remote machine. The only limitation is that the HTML client supports the JavaScript features used by qwebchannel.js. As such, one can interact with basically any modern HTML browser or standalone JavaScript runtime, such as node.js.

There also exists a declarative WebChannel API .

See also

Qt WebChannel Standalone Example JavaScript API registerConverter()

Note

Properties can be used directly when from __feature__ import true_property is used or via accessor functions otherwise.

property blockUpdatesᅟ: bool

This property holds When set to true, updates are blocked and remote clients will not be notified about property changes..

The changes are recorded and sent to the clients once updates become unblocked again by setting this property to false. By default, updates are not blocked.

Access functions:
property propertyUpdateIntervalᅟ: int

This property holds The property update interval..

This interval can be changed to a different interval in milliseconds by setting it to a positive value. Property updates are batched and sent out after the interval expires. If set to zero, the updates occurring within a single event loop run are batched and sent out on the next run. If negative, updates will be sent immediately. Default value is 50 milliseconds.

Access functions:
__init__([parent=None])
Parameters:

parent – QObject

Constructs the QWebChannel object with the given parent.

Note that a QWebChannel is only fully operational once you connect it to a QWebChannelAbstractTransport . The HTML clients also need to be setup appropriately using qwebchannel.js :ref:` <Qt-WebChannel-JavaScript-API>` .

blockUpdates()
Return type:

bool

See also

setBlockUpdates()

Getter of property blockUpdatesᅟ .

blockUpdatesChanged(block)
Parameters:

block – bool

Notification signal of property blockUpdatesᅟ .

connectTo(transport)
Parameters:

transport – QWebChannelAbstractTransport

Connects the QWebChannel to the given transport object.

The transport object then handles the communication between the C++ application and a remote HTML client.

deregisterObject(object)
Parameters:

object – QObject

Deregisters the given object from the QWebChannel .

Remote clients will receive a destroyed signal for the given object.

disconnectFrom(transport)
Parameters:

transport – QWebChannelAbstractTransport

Disconnects the QWebChannel from the transport object.

See also

connectTo()

propertyUpdateInterval()
Return type:

int

See also

setPropertyUpdateInterval()

Getter of property propertyUpdateIntervalᅟ .

registerObject(id, object)
Parameters:

Registers a single object to the QWebChannel .

The properties, signals and public methods of the object are published to the remote clients. There, an object with the identifier id is then constructed.

A property that is BINDABLE but does not have a NOTIFY signal will have working property updates on the client side, but no mechanism to register a callback for the change notifications.

Note

A current limitation is that objects must be registered before any client is initialized.

See also

registerObjects() deregisterObject() registeredObjects()

registerObjects(objects)
Parameters:

objects – Dictionary with keys of type .QString and values of type QObject.

Registers a group of objects to the QWebChannel .

The properties, signals and public invokable methods of the objects are published to the remote clients. There, an object with the identifier used as key in the objects map is then constructed.

Note

A current limitation is that objects must be registered before any client is initialized.

See also

registerObject() deregisterObject() registeredObjects()

registeredObjects()
Return type:

Dictionary with keys of type .QString and values of type QObject.

Returns the map of registered objects that are published to remote clients.

setBlockUpdates(block)
Parameters:

block – bool

See also

blockUpdates()

Setter of property blockUpdatesᅟ .

setPropertyUpdateInterval(ms)
Parameters:

ms – int

See also

propertyUpdateInterval()

Setter of property propertyUpdateIntervalᅟ .