Synopsis#

Virtual methods#

def create()

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#

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

A QML engine uses QNetworkAccessManager for all network access. By implementing a factory, it is possible to provide the QML engine with custom QNetworkAccessManager instances with specialized caching, proxy and cookies support.

The QNetworkDiskCache can be used as a request cache with QNetworkDiskCache.

Using QNetworkProxy, traffic sent by the QNetworkAccessManager can be tunnelled through a proxy.

Cookies can be saved for future requests by adding a QNetworkCookieJar.

To implement a factory, subclass QQmlNetworkAccessManagerFactory and implement the virtual create() method, then assign it to the relevant QML engine using setNetworkAccessManagerFactory() . For instance, the QNetworkAccessManager objects created by the following snippet will cache requests.

class CachingNetworkAccessManagerFactory(QQmlNetworkAccessManagerFactory):

# public
    QNetworkAccessManager create(QObject parent) override

        networkAccessManager = QNetworkAccessManager(parent)
        diskCache = QNetworkDiskCache(parent)
        diskCache.setCacheDirectory("requestCache")
        networkAccessManager.setCache(diskCache)
        return networkAccessManager

The factory can then be passed to the QML engine so it can instantiate the QNetworkAccessManager with the custom behavior.

networkManagerFactory = CachingNetworkAccessManagerFactory()
engine.setNetworkAccessManagerFactory(networkManagerFactory)

Note the QML engine may create QNetworkAccessManager instances from multiple threads. Because of this, the implementation of the create() method must be reentrant. In addition, the developer should be careful if the signals of the object to be returned from create() are connected to the slots of an object that may be created in a different thread:

The QML engine internally handles all requests, and cleans up any QNetworkReply objects it creates. Receiving the QNetworkAccessManager::finished() signal in another thread may not provide the receiver with a valid reply object if it has already been deleted.

Authentication details provided to QNetworkAccessManager::authenticationRequired() must be provided immediately, so this signal cannot be connected as a Qt::QueuedConnection (or as the default Qt::AutoConnection from another thread).

For more information about signals and threads, see Threads and QObjects and Signals and Slots Across Threads.

See also

QNetworkDiskCache

abstract create(parent)#

Parameters:: parent – QObject
Return type:: QNetworkAccessManager

Creates and returns a network access manager with the specified parent. This method must return a new QNetworkAccessManager instance each time it is called.

Note: this method may be called by multiple threads, so ensure the implementation of this method is reentrant.