QNetworkReply — PyQt Documentation v6.9.0 (original) (raw)

PyQt6.QtNetwork.QNetworkReply

Inherits from QIODevice.

Description¶

The QNetworkReply class contains the data and headers for a request sent with QNetworkAccessManager.

The QNetworkReply class contains the data and meta data related to a request posted with QNetworkAccessManager. Like QNetworkRequest, it contains a URL and headers (both in parsed and raw form), some information about the reply’s state and the contents of the reply itself.

QNetworkReply is a sequential-access QIODevice, which means that once data is read from the object, it no longer kept by the device. It is therefore the application’s responsibility to keep this data if it needs to. Whenever more data is received from the network and processed, the readyRead() signal is emitted.

The downloadProgress signal is also emitted when data is received, but the number of bytes contained in it may not represent the actual bytes received, if any transformation is done to the contents (for example, decompressing and removing the protocol overhead).

Even though QNetworkReply is a QIODevice connected to the contents of the reply, it also emits the uploadProgress signal, which indicates the progress of the upload for operations that have such content.

Note: Do not delete the object in the slot connected to the errorOccurred or finished signal. Use deleteLater().

Enums¶

NetworkError

Indicates all possible error conditions found during the processing of the request.

Note: When the HTTP protocol returns a redirect no error will be reported. You can check if there is a redirect with the RedirectionTargetAttribute attribute.

See also

error(), errorOccurred.

Methods¶

__init__(parent: QObject = None)

Creates a QNetworkReply object with parent parent.

You cannot directly instantiate QNetworkReply objects. Use QNetworkAccessManager functions to do that.

abort()

TODO

attribute(Attribute) → Any

Returns the attribute associated with the code code. If the attribute has not been set, it returns an invalid QVariant (type UnknownType).

You can expect the default values listed in Attribute to be applied to the values returned by this function.

close()

TODO

error() → NetworkError

Returns the error that was found during the processing of this request. If no error was found, returns NoError.

Returns true if the raw header of name headerName was sent by the remote server

Note: In Qt versions prior to 6.7, this function took QByteArray only.

Returns the value of the known header header, if that header was sent by the remote server. If the header was not sent, returns an invalid QVariant.

Returns headers that were sent by the remote server.

ignoreSslErrors()

If this function is called, SSL errors related to network connection will be ignored, including certificate validation errors.

Warning: Be sure to always let the user inspect the errors reported by the sslErrors signal, and only call this method upon confirmation from the user that proceeding is ok. If there are unexpected errors, the reply should be aborted. Calling this method without inspecting the actual errors will most likely pose a security risk for your application. Use it with great care!

This function can be called from the slot connected to the sslErrors signal, which indicates which errors were found.

Note: If HTTP Strict Transport Security is enabled for QNetworkAccessManager, this function has no effect.

ignoreSslErrors(Iterable[QSslError])

This is an overloaded function.

If this function is called, the SSL errors given in errors will be ignored.

Note: Because most SSL errors are associated with a certificate, for most of them you must set the expected certificate this SSL error is related to. If, for instance, you want to issue a request to a server that uses a self-signed certificate, consider the following snippet:

QList cert = QSslCertificate::fromPath(QLatin1String("server-certificate.pem"));

QSslError error(QSslError::SelfSignedCertificate, cert.at(0));

QList expectedSslErrors;

expectedSslErrors.append(error);

QNetworkReply *reply = manager.get(QNetworkRequest(QUrl("https://server.tld/index.html")));

reply->ignoreSslErrors(expectedSslErrors);

// here connect signals etc.

Multiple calls to this function will replace the list of errors that were passed in previous calls. You can clear the list of errors you want to ignore by calling this function with an empty list.

Note: If HTTP Strict Transport Security is enabled for QNetworkAccessManager, this function has no effect.

ignoreSslErrorsImplementation(Iterable[QSslError])

This virtual method is provided to enable overriding the behavior of ignoreSslErrors(). ignoreSslErrors() is a public wrapper for this method. errors contains the errors the user wishes ignored.

See also

ignoreSslErrors().

isFinished() → bool

Returns true when the reply has finished or was aborted.

isRunning() → bool

Returns true when the request is still processing and the reply has not finished or was aborted yet.

isSequential() → bool

TODO

manager() → QNetworkAccessManager

Returns the QNetworkAccessManager that was used to create this QNetworkReply object. Initially, it is also the parent object.

operation() → Operation

Returns the operation that was posted for this reply.

Returns the raw contents of the header headerName as sent by the remote server. If there is no such header, returns an empty byte array, which may be indistinguishable from an empty header. Use hasRawHeader() to verify if the server sent such header field.

Note: In Qt versions prior to 6.7, this function took QByteArray only.

Returns a list of headers fields that were sent by the remote server, in the order that they were sent. Duplicate headers are merged together and take place of the latter duplicate.

Returns a list of raw header pairs.

readBufferSize() → int

Returns the size of the read buffer, in bytes.

See also

setReadBufferSize().

request() → QNetworkRequest

Returns the request that was posted for this reply. In special, note that the URL for the request may be different than that of the reply.

setAttribute(Attribute, Any)

Sets the attribute code to have value value. If code was previously set, it will be overridden. If value is an invalid QVariant, the attribute will be unset.

setError(NetworkError, Optional[str])

Sets the error condition to be errorCode. The human-readable message is set with errorString.

Calling setError() does not emit the errorOccurred(NetworkError) signal.

See also

error(), errorString().

setFinished(bool)

Sets the reply as finished.

After having this set the replies data must not change.

See also

finished, isFinished().

Sets the known header header to be of value value. The corresponding raw form of the header will be set as well.

Sets newHeaders as headers in this network reply, overriding any previously set headers.

If some headers correspond to the known headers, they will be parsed and the corresponding parsed form will also be set.

setOperation(Operation)

Sets the associated operation for this object to be operation. This value will be returned by operation().

Note: The operation should be set when this object is created and not changed again.

See also

operation(), setRequest().

Sets the raw header headerName to be of value value. If headerName was previously set, it is overridden. Multiple HTTP headers of the same name are functionally equivalent to one single header with the values concatenated, separated by commas.

If headerName matches a known header, the value value will be parsed and the corresponding parsed form will also be set.

setReadBufferSize(int)

Sets the size of the read buffer to be size bytes. The read buffer is the buffer that holds data that is being downloaded off the network, before it is read with read(). Setting the buffer size to 0 will make the buffer unlimited in size.

QNetworkReply will try to stop reading from the network once this buffer is full (i.e., bytesAvailable() returns size or more), thus causing the download to throttle down as well. If the buffer is not limited in size, QNetworkReply will try to download as fast as possible from the network.

Unlike setReadBufferSize(), QNetworkReply cannot guarantee precision in the read buffer size. That is, bytesAvailable() can return more than size.

See also

readBufferSize().

setRequest(QNetworkRequest)

Sets the associated request for this object to be request. This value will be returned by request().

Note: The request should be set when this object is created and not changed again.

See also

request(), setOperation().

setSslConfiguration(QSslConfiguration)

Sets the SSL configuration for the network connection associated with this request, if possible, to be that of config.

See also

sslConfiguration().

setSslConfigurationImplementation(QSslConfiguration)

This virtual method is provided to enable overriding the behavior of setSslConfiguration(). setSslConfiguration() is a public wrapper for this method. If you override this method use configuration to set the SSL configuration.

setUrl(QUrl)

Sets the URL being processed to be url. Normally, the URL matches that of the request that was posted, but for a variety of reasons it can be different (for example, a file path being made absolute or canonical).

Sets the header name to be of value value. If name was previously set, it is overridden.

sslConfiguration() → QSslConfiguration

Returns the SSL configuration and state associated with this reply, if SSL was used. It will contain the remote server’s certificate, its certificate chain leading to the Certificate Authority as well as the encryption ciphers in use.

The peer’s certificate and its certificate chain will be known by the time sslErrors is emitted, if it’s emitted.

sslConfigurationImplementation(QSslConfiguration)

This virtual method is provided to enable overriding the behavior of sslConfiguration(). sslConfiguration() is a public wrapper for this method. The configuration will be returned in configuration.

url() → QUrl

Returns the URL of the content downloaded or uploaded. Note that the URL may be different from that of the original request. If redirections were enabled in the request, then this function returns the current url that the network API is accessing, i.e the url of the resource the request got redirected to.

writeData(Union[bytes, bytearray, memoryview, PyQt6.sip.array, PyQt6.sip.voidptr]) → int

TODO

Signals¶

downloadProgress(int, int)

This signal is emitted to indicate the progress of the download part of this network request, if there’s any. If there’s no download associated with this request, this signal will be emitted once with 0 as the value of both bytesReceived and bytesTotal.

The bytesReceived parameter indicates the number of bytes received, while bytesTotal indicates the total number of bytes expected to be downloaded. If the number of bytes to be downloaded is not known, bytesTotal will be -1.

The download is finished when bytesReceived is equal to bytesTotal. At that time, bytesTotal will not be -1.

Note that the values of both bytesReceived and bytesTotal may be different from size(), the total number of bytes obtained through read() or readAll(), or the value of the header(ContentLengthHeader). The reason for that is that there may be protocol overhead or the data may be compressed during the download.

See also

uploadProgress, bytesAvailable().

encrypted()

This signal is emitted when an SSL/TLS session has successfully completed the initial handshake. At this point, no user data has been transmitted. The signal can be used to perform additional checks on the certificate chain, for example to notify users when the certificate for a website has changed. If the reply does not match the expected criteria then it should be aborted by calling abort() by a slot connected to this signal. The SSL configuration in use can be inspected using the sslConfiguration() method.

Internally, QNetworkAccessManager may open multiple connections to a server, in order to allow it process requests in parallel. These connections may be reused, which means that the signal would not be emitted. This means that you are only guaranteed to receive this signal for the first connection to a site in the lifespan of the QNetworkAccessManager.

errorOccurred(NetworkError)

This signal is emitted when the reply detects an error in processing. The finished signal will probably follow, indicating that the connection is over.

The code parameter contains the code of the error that was detected. Call errorString() to obtain a textual representation of the error condition.

Note: Do not delete the object in the slot connected to this signal. Use deleteLater().

See also

error(), errorString().

finished()

This signal is emitted when the reply has finished processing. After this signal is emitted, there will be no more updates to the reply’s data or metadata.

Unless close() or abort() have been called, the reply will be still be opened for reading, so the data can be retrieved by calls to read() or readAll(). In particular, if no calls to read() were made as a result of readyRead(), a call to readAll() will retrieve the full contents in a QByteArray.

This signal is emitted in tandem with finished where that signal’s reply parameter is this object.

Note: Do not delete the object in the slot connected to this signal. Use deleteLater().

You can also use isFinished() to check if a QNetworkReply has finished even before you receive the signal.

metaDataChanged()

This signal is emitted whenever the metadata in this reply changes. metadata is any information that is not the content (data) itself, including the network headers. In the majority of cases, the metadata will be known fully by the time the first byte of data is received. However, it is possible to receive updates of headers or other metadata during the processing of the data.

preSharedKeyAuthenticationRequired(QSslPreSharedKeyAuthenticator)

This signal is emitted if the SSL/TLS handshake negotiates a PSK ciphersuite, and therefore a PSK authentication is then required.

When using PSK, the client must send to the server a valid identity and a valid pre shared key, in order for the SSL handshake to continue. Applications can provide this information in a slot connected to this signal, by filling in the passed authenticator object according to their needs.

Note: Ignoring this signal, or failing to provide the required credentials, will cause the handshake to fail, and therefore the connection to be aborted.

Note: The authenticator object is owned by the reply and must not be deleted by the application.

redirectAllowed()

When client code handling the redirected signal has verified the new URL, it emits this signal to allow the redirect to go ahead. This protocol applies to network requests whose redirects policy is set to UserVerifiedRedirectPolicy

redirected(QUrl)

This signal is emitted if the ManualRedirectPolicy was set in the request and the server responded with a 3xx status (specifically 301, 302, 303, 305, 307 or 308 status code) with a valid url in the location header, indicating a HTTP redirect. The url parameter contains the new redirect url as returned by the server in the location header.

requestSent()

This signal is emitted 1 or more times when the request was sent. Useful for custom progress or timeout handling.

socketStartedConnecting()

This signal is emitted 0 or more times, when the socket is connecting, before sending the request. Useful for custom progress or timeout handling.

sslErrors(Iterable[QSslError])

This signal is emitted if the SSL/TLS session encountered errors during the set up, including certificate verification errors. The errors parameter contains the list of errors.

To indicate that the errors are not fatal and that the connection should proceed, the ignoreSslErrors() function should be called from the slot connected to this signal. If it is not called, the SSL session will be torn down before any data is exchanged (including the URL).

This signal can be used to display an error message to the user indicating that security may be compromised and display the SSL settings (see sslConfiguration() to obtain it). If the user decides to proceed after analyzing the remote certificate, the slot should call ignoreSslErrors().

uploadProgress(int, int)

This signal is emitted to indicate the progress of the upload part of this network request, if there’s any. If there’s no upload associated with this request, this signal will not be emitted.

The bytesSent parameter indicates the number of bytes uploaded, while bytesTotal indicates the total number of bytes to be uploaded. If the number of bytes to be uploaded could not be determined, bytesTotal will be -1.

The upload is finished when bytesSent is equal to bytesTotal. At that time, bytesTotal will not be -1.

See also

downloadProgress.