QNetworkAccessManager¶

PyQt5.QtNetwork.QNetworkAccessManager: Inherits from QObject.

Description¶

The QNetworkAccessManager class allows the application to send network requests and receive replies.

The Network Access API is constructed around one QNetworkAccessManager object, which holds the common configuration and settings for the requests it sends. It contains the proxy and cache configuration, as well as the signals related to such issues, and reply signals that can be used to monitor the progress of a network operation. One QNetworkAccessManager instance should be enough for the whole Qt application. Since QNetworkAccessManager is based on QObject, it can only be used from the thread it belongs to.

Once a QNetworkAccessManager object has been created, the application can use it to send requests over the network. A group of standard functions are supplied that take a request and optional data, and each return a QNetworkReply object. The returned object is used to obtain any data returned in response to the corresponding request.

A simple download off the network could be accomplished with:

# QNetworkAccessManager *manager = new QNetworkAccessManager(this);
# connect(manager, &QNetworkAccessManager::finished,
#         this, &MyClass::replyFinished);

# manager->get(QNetworkRequest(QUrl("http://qt-project.org")));

QNetworkAccessManager has an asynchronous API. When the replyFinished slot above is called, the parameter it takes is the QNetworkReply object containing the downloaded data as well as meta-data (headers, etc.).

Note: After the request has finished, it is the responsibility of the user to delete the QNetworkReply object at an appropriate time. Do not directly delete it inside the slot connected to finished. You can use the deleteLater() function.

Note: QNetworkAccessManager queues the requests it receives. The number of requests executed in parallel is dependent on the protocol. Currently, for the HTTP protocol on desktop platforms, 6 requests are executed in parallel for one host/port combination.

A more involved example, assuming the manager is already existent, can be:

# QNetworkRequest request;
# request.setUrl(QUrl("http://qt-project.org"));
# request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");

# QNetworkReply *reply = manager->get(request);
# connect(reply, &QIODevice::readyRead, this, &MyClass::slotReadyRead);
# connect(reply, QOverload<QNetworkReply::NetworkError>::of(&QNetworkReply::error),
#         this, &MyClass::slotError);
# connect(reply, &QNetworkReply::sslErrors,
#         this, &MyClass::slotSslErrors);

Network and Roaming Support¶

With the addition of the Bearer Management API to Qt 4.7 QNetworkAccessManager gained the ability to manage network connections. QNetworkAccessManager can start the network interface if the device is offline and terminates the interface if the current process is the last one to use the uplink. Note that some platforms utilize grace periods from when the last application stops using a uplink until the system actually terminates the connectivity link. Roaming is equally transparent. Any queued/pending network requests are automatically transferred to the new access point.

Clients wanting to utilize this feature should not require any changes. In fact it is likely that existing platform specific connection code can simply be removed from the application.

Note: The network and roaming support in QNetworkAccessManager is conditional upon the platform supporting connection management. The NetworkSessionRequired can be used to detect whether QNetworkAccessManager utilizes this feature.

Enums¶

NetworkAccessibility

Indicates whether the network is accessible via this network access manager.

See also

networkAccessible().

Member	Value	Description
Accessible	1	The network is accessible.
NotAccessible	0	The network is not currently accessible, either because there is currently no network coverage or network access has been explicitly disabled by a call to setNetworkAccessible().
UnknownAccessibility	-1	The network accessibility cannot be determined.

Operation

Indicates the operation this reply is processing.

See also

operation().

Member	Value	Description
CustomOperation	6	custom operation (created with sendCustomRequest())
DeleteOperation	5	delete contents operation (created with deleteResource())
GetOperation	2	retrieve headers and download contents (created with get())
HeadOperation	1	retrieve headers operation (created with head())
PostOperation	4	send the contents of an HTML form for processing via HTTP POST (created with post())
PutOperation	3	upload contents operation (created with put())

Methods¶

__init__(parent: QObject = None): Constructs a QNetworkAccessManager object that is the center of the Network Access API and sets parent as the parent object.

activeConfiguration() → QNetworkConfiguration

Returns the current active network configuration.

If the network configuration returned by configuration() is of type ServiceNetwork this function will return the current active child network configuration of that configuration. Otherwise returns the same network configuration as configuration().

Use this function to return the actual network configuration currently in use by the network session.

See also

configuration().

addStrictTransportSecurityHosts(Iterable[QHstsPolicy]): TODO

autoDeleteReplies() → bool: TODO

cache() → QAbstractNetworkCache: Returns the cache that is used to store data obtained from the network.

See also

setCache().

clearAccessCache(): TODO

clearConnectionCache(): TODO

configuration() → QNetworkConfiguration: Returns the network configuration that will be used to create the QNetworkSession which will be used when processing network requests.

See also

setConfiguration(), activeConfiguration().

connectToHost(str, port: int = 80): TODO

connectToHostEncrypted(str, port: int = 443, sslConfiguration: QSslConfiguration = QSslConfiguration.defaultConfiguration()): TODO

connectToHostEncrypted(str, int, QSslConfiguration, str): TODO

cookieJar() → QNetworkCookieJar: Returns the QNetworkCookieJar that is used to store cookies obtained from the network as well as cookies that are about to be sent.

See also

setCookieJar().

createRequest(Operation, QNetworkRequest, device: QIODevice = None) → QNetworkReply

Returns a new QNetworkReply object to handle the operation op and request originalReq. The device outgoingData is always 0 for Get and Head requests, but is the value passed to post() and put() in those operations (the QByteArray variants will pass a QBuffer object).

The default implementation calls cookiesForUrl() on the cookie jar set with setCookieJar() to obtain the cookies to be sent to the remote server.

The returned object must be in an open state.

deleteResource(QNetworkRequest) → QNetworkReply

Sends a request to delete the resource identified by the URL of request.

Note: This feature is currently available for HTTP only, performing an HTTP DELETE request.

enableStrictTransportSecurityStore(bool, storeDir: str = ''): TODO

get(QNetworkRequest) → QNetworkReply

Posts a request to obtain the contents of the target request and returns a new QNetworkReply object opened for reading which emits the readyRead signal whenever new data arrives.

The contents as well as associated headers will be downloaded.

head(QNetworkRequest) → QNetworkReply

Posts a request to obtain the network headers for request and returns a new QNetworkReply object which will contain such headers.

The function is named after the HTTP request associated (HEAD).

isStrictTransportSecurityEnabled() → bool: TODO

isStrictTransportSecurityStoreEnabled() → bool: TODO

networkAccessible() → NetworkAccessibility: Returns the current network accessibility.

See also

setNetworkAccessible().

post(QNetworkRequest, QIODevice) → QNetworkReply

Sends an HTTP POST request to the destination specified by request and returns a new QNetworkReply object opened for reading that will contain the reply sent by the server. The contents of the data device will be uploaded to the server.

data must be open for reading and must remain valid until the finished signal is emitted for this reply.

Note: Sending a POST request on protocols other than HTTP and HTTPS is undefined and will probably fail.

post(QNetworkRequest, Union[QByteArray, bytes, bytearray]) → QNetworkReply

This is an overloaded function.

Sends the contents of the data byte array to the destination specified by request.

post(QNetworkRequest, QHttpMultiPart) → QNetworkReply: TODO

proxy() → QNetworkProxy: Returns the QNetworkProxy that the requests sent using this QNetworkAccessManager object will use. The default value for the proxy is DefaultProxy.

See also

setProxy(), setProxyFactory(), proxyAuthenticationRequired.

proxyFactory() → QNetworkProxyFactory: See also

setProxyFactory().

put(QNetworkRequest, QIODevice) → QNetworkReply

Uploads the contents of data to the destination request and returns a new QNetworkReply object that will be open for reply.

data must be opened for reading when this function is called and must remain valid until the finished signal is emitted for this reply.

Whether anything will be available for reading from the returned object is protocol dependent. For HTTP, the server may send a small HTML page indicating the upload was successful (or not). Other protocols will probably have content in their replies.

Note: For HTTP, this request will send a PUT request, which most servers do not allow. Form upload mechanisms, including that of uploading files through HTML forms, use the POST mechanism.

put(QNetworkRequest, Union[QByteArray, bytes, bytearray]) → QNetworkReply

This is an overloaded function.

Sends the contents of the data byte array to the destination specified by request.

put(QNetworkRequest, QHttpMultiPart) → QNetworkReply: TODO

redirectPolicy() → RedirectPolicy: TODO

sendCustomRequest(QNetworkRequest, Union[QByteArray, bytes, bytearray], data: QIODevice = None) → QNetworkReply

Sends a custom request to the server identified by the URL of request.

It is the user’s responsibility to send a verb to the server that is valid according to the HTTP specification.

This method provides means to send verbs other than the common ones provided via get() or post() etc., for instance sending an HTTP OPTIONS command.

If data is not empty, the contents of the data device will be uploaded to the server; in that case, data must be open for reading and must remain valid until the finished signal is emitted for this reply.

Note: This feature is currently available for HTTP(S) only.

See also

get(), post(), put(), deleteResource().

sendCustomRequest(QNetworkRequest, Union[QByteArray, bytes, bytearray], Union[QByteArray, bytes, bytearray]) → QNetworkReply: TODO

sendCustomRequest(QNetworkRequest, Union[QByteArray, bytes, bytearray], QHttpMultiPart) → QNetworkReply: TODO

setAutoDeleteReplies(bool): TODO

setCache(QAbstractNetworkCache)

Sets the manager’s network cache to be the cache specified. The cache is used for all requests dispatched by the manager.

Use this function to set the network cache object to a class that implements additional features, like saving the cookies to permanent storage.

Note: QNetworkAccessManager takes ownership of the cache object.

QNetworkAccessManager by default does not have a set cache. Qt provides a simple disk cache, QNetworkDiskCache, which can be used.

See also

cache(), CacheLoadControl.

setConfiguration(QNetworkConfiguration)

Sets the network configuration that will be used when creating the QNetworkSession to config.

The network configuration is used to create and open a network session before any request that requires network access is process. If no network configuration is explicitly set via this function the network configuration returned by defaultConfiguration() will be used.

To restore the default network configuration set the network configuration to the value returned from defaultConfiguration().

Setting a network configuration means that the QNetworkAccessManager instance will only be using the specified one. In particular, if the default network configuration changes (upon e.g. Wifi being available), this new configuration needs to be enabled manually if desired.

# QNetworkConfigurationManager manager;
# networkAccessManager->setConfiguration(manager.defaultConfiguration());

If an invalid network configuration is set, a network session will not be created. In this case network requests will be processed regardless, but may fail. For example:

# networkAccessManager->setConfiguration(QNetworkConfiguration());

See also

configuration(), QNetworkSession.

setCookieJar(QNetworkCookieJar)

Sets the manager’s cookie jar to be the cookieJar specified. The cookie jar is used by all requests dispatched by the manager.

Use this function to set the cookie jar object to a class that implements additional features, like saving the cookies to permanent storage.

Note: QNetworkAccessManager takes ownership of the cookieJar object.

If cookieJar is in the same thread as this QNetworkAccessManager, it will set the parent of the cookieJar so that the cookie jar is deleted when this object is deleted as well. If you want to share cookie jars between different QNetworkAccessManager objects, you may want to set the cookie jar’s parent to 0 after calling this function.

QNetworkAccessManager by default does not implement any cookie policy of its own: it accepts all cookies sent by the server, as long as they are well formed and meet the minimum security requirements (cookie domain matches the request’s and cookie path matches the request’s). In order to implement your own security policy, override the cookiesForUrl() and setCookiesFromUrl() virtual functions. Those functions are called by QNetworkAccessManager when it detects a new cookie.

setNetworkAccessible(NetworkAccessibility): Overrides the reported network accessibility. If accessible is NotAccessible the reported network accessiblity will always be NotAccessible. Otherwise the reported network accessibility will reflect the actual device state.

See also

networkAccessible().

setProxy(QNetworkProxy)

Sets the proxy to be used in future requests to be proxy. This does not affect requests that have already been sent. The proxyAuthenticationRequired signal will be emitted if the proxy requests authentication.

A proxy set with this function will be used for all requests issued by QNetworkAccessManager. In some cases, it might be necessary to select different proxies depending on the type of request being sent or the destination host. If that’s the case, you should consider using setProxyFactory().

See also

proxy(), proxyAuthenticationRequired.

setProxyFactory(QNetworkProxyFactory)

Sets the proxy factory for this class to be factory. A proxy factory is used to determine a more specific list of proxies to be used for a given request, instead of trying to use the same proxy value for all requests.

All queries sent by QNetworkAccessManager will have type UrlRequest.

For example, a proxy factory could apply the following rules:

if the target address is in the local network (for example, if the hostname contains no dots or if it’s an IP address in the organization’s range), return NoProxy
if the request is FTP, return an FTP proxy
if the request is HTTP or HTTPS, then return an HTTP proxy
otherwise, return a SOCKSv5 proxy server

The lifetime of the object factory will be managed by QNetworkAccessManager. It will delete the object when necessary.

Note: If a specific proxy is set with setProxy(), the factory will not be used.

setRedirectPolicy(RedirectPolicy): TODO

setStrictTransportSecurityEnabled(bool): TODO

strictTransportSecurityHosts() → List[QHstsPolicy]: TODO

supportedSchemes() → List[str]: TODO

supportedSchemesImplementation() → List[str]: TODO

Signals¶

authenticationRequired(QNetworkReply, QAuthenticator): TODO

encrypted(QNetworkReply): TODO

finished(QNetworkReply): TODO

networkAccessibleChanged(NetworkAccessibility): TODO

preSharedKeyAuthenticationRequired(QNetworkReply, QSslPreSharedKeyAuthenticator): TODO

proxyAuthenticationRequired(QNetworkProxy, QAuthenticator): TODO

sslErrors(QNetworkReply, Iterable[QSslError]): TODO