class QBluetoothServiceDiscoveryAgent¶

The QBluetoothServiceDiscoveryAgent class enables you to query for Bluetooth services. More…

Synopsis¶

Methods¶

def __init__()
def discoveredServices()
def error()
def errorString()
def isActive()
def remoteAddress()
def setRemoteAddress()
def setUuidFilter()
def uuidFilter()

Slots¶

def clear()
def start()
def stop()

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.

The discovery process relies on the Bluetooth Service Discovery Process (SDP). The following steps are required to query the services provided by all contactable Bluetooth devices:

create an instance of QBluetoothServiceDiscoveryAgent ,
connect to either the serviceDiscovered() or finished() signals,
and call start() .

def startServiceDiscovery(self):

    # Create a discovery agent and connect to its signals
    discoveryAgent = QBluetoothServiceDiscoveryAgent(self)
    connect(discoveryAgent, SIGNAL(serviceDiscovered(QBluetoothServiceInfo)),
            self, SLOT(serviceDiscovered(QBluetoothServiceInfo)))
    # Start a discovery
    discoveryAgent.start()
    #...

# In your local slot, read information about the found devices
def serviceDiscovered(self, service):

    print("Found service():", service.serviceName())
             << '(' << service.device().address().toString() << ')'

By default a minimal service discovery is performed. In this mode, the returned QBluetoothServiceInfo objects are guaranteed to contain only device and service UUID information. Depending on platform and device capabilities, other service information may also be available. The minimal service discovery mode relies on cached SDP data of the platform. Therefore it is possible that this discovery does not find a device although it is physically available. In such cases a full discovery must be performed to force an update of the platform cache. However for most use cases a minimal discovery is adequate as it is much quicker and other classes which require up-to-date information such as connectToService() will perform additional discovery if required. If the full service information is required, pass FullDiscovery as the discoveryMode parameter to start() .

This class may internally utilize QBluetoothDeviceDiscoveryAgent to find unknown devices.

The service discovery may find Bluetooth Low Energy services too if the target device is a combination of a classic and Low Energy device. Those devices are required to advertise their Low Energy services via SDP. If the target device only supports Bluetooth Low Energy services, it is likely to not advertise them via SDP. The QLowEnergyController class should be utilized to perform the service discovery on Low Energy devices.

On iOS, this class cannot be used because the platform does not expose an API which may permit access to QBluetoothServiceDiscoveryAgent related features.

See also

QBluetoothDeviceDiscoveryAgent QLowEnergyController

class Error¶

This enum describes errors that can occur during service discovery.

Constant

Description

QBluetoothServiceDiscoveryAgent.NoError

No error has occurred.

QBluetoothServiceDiscoveryAgent.PoweredOffError

The Bluetooth adaptor is powered off, power it on before doing discovery.

QBluetoothServiceDiscoveryAgent.InputOutputError

Writing or reading from the device resulted in an error.

QBluetoothServiceDiscoveryAgent.InvalidBluetoothAdapterError

The passed local adapter address does not match the physical adapter address of any local Bluetooth device.

QBluetoothServiceDiscoveryAgent.MissingPermissionsError

The operating system requests permissions which were not granted by the user.

QBluetoothServiceDiscoveryAgent.UnknownError

An unknown error has occurred.

Constant	Description
QBluetoothServiceDiscoveryAgent.NoError	No error has occurred.
QBluetoothServiceDiscoveryAgent.PoweredOffError	The Bluetooth adaptor is powered off, power it on before doing discovery.
QBluetoothServiceDiscoveryAgent.InputOutputError	Writing or reading from the device resulted in an error.
QBluetoothServiceDiscoveryAgent.InvalidBluetoothAdapterError	The passed local adapter address does not match the physical adapter address of any local Bluetooth device.
QBluetoothServiceDiscoveryAgent.MissingPermissionsError	The operating system requests permissions which were not granted by the user.
QBluetoothServiceDiscoveryAgent.UnknownError	An unknown error has occurred.

class DiscoveryMode¶

This enum describes the service discovery mode.

Constant

Description

QBluetoothServiceDiscoveryAgent.MinimalDiscovery

Performs a minimal service discovery. The QBluetoothServiceInfo objects returned may be incomplete and are only guaranteed to contain device and service UUID information. Since a minimal discovery relies on cached SDP data it may not find a physically existing device until a FullDiscovery is performed.

QBluetoothServiceDiscoveryAgent.FullDiscovery

Performs a full service discovery.

Constant	Description
QBluetoothServiceDiscoveryAgent.MinimalDiscovery	Performs a minimal service discovery. The `QBluetoothServiceInfo` objects returned may be incomplete and are only guaranteed to contain device and service UUID information. Since a minimal discovery relies on cached SDP data it may not find a physically existing device until a `FullDiscovery` is performed.
QBluetoothServiceDiscoveryAgent.FullDiscovery	Performs a full service discovery.

__init__([parent=None])¶

Parameters:: parent – QObject

Constructs a new QBluetoothServiceDiscoveryAgent with parent. The search is performed via the local default Bluetooth adapter.

__init__(deviceAdapter[, parent=None])

Parameters:

deviceAdapter – QBluetoothAddress
parent – QObject

Constructs a new QBluetoothServiceDiscoveryAgent for deviceAdapter and with parent.

It uses deviceAdapter for the service search. If deviceAdapter is default constructed the resulting QBluetoothServiceDiscoveryAgent object will use the local default Bluetooth adapter.

If a deviceAdapter is specified that is not a local adapter error() will be set to InvalidBluetoothAdapterError . Therefore it is recommended to test the error flag immediately after using this constructor.

Note

On WinRT the passed adapter address will be ignored.

Note

On Android passing any deviceAdapter address is meaningless as Android 6.0 or later does not publish the local Bluetooth address anymore. Subsequently, the passed adapter address can never be matched against the local adapter address. Therefore the subsequent call to start() will always trigger InvalidBluetoothAdapterError .

See also

clear()

error()¶

Return type:: Error

Returns the type of error that last occurred. If the service discovery is done for a single remoteAddress() it will return errors that occurred while trying to discover services on that device. If the remoteAddress() is not set and devices are discovered by a scan, errors during service discovery on individual devices are not saved and no signals are emitted. In this case, errors are fairly normal as some devices may not respond to discovery or may no longer be in range. Such errors are suppressed. If no services are returned, it can be assumed no services could be discovered.

Any possible previous errors are cleared upon restarting the discovery.

errorOccurred(error)¶

Parameters:: error – Error

This signal is emitted when an error occurs. The error parameter describes the error that occurred.

errorString()¶

Return type:: str

Returns a human-readable description of the last error that occurred during the service discovery.

See also

error() errorOccurred()

finished()¶

This signal is emitted when the Bluetooth service discovery completes.

Unlike the finished() signal this signal will even be emitted when an error occurred during the service discovery. Therefore it is recommended to check the errorOccurred() signal to evaluate the success of the service discovery discovery.

isActive()¶

Return type:: bool

Returns true if the service discovery is currently active; otherwise returns false. An active discovery can be stopped by calling stop() .

remoteAddress()¶

Return type:: QBluetoothAddress

Returns the remote device address. If setRemoteAddress() is not called, the function will return a default constructed QBluetoothAddress .

See also

setRemoteAddress()

serviceDiscovered(info)¶

Parameters:: info – QBluetoothServiceInfo

This signal is emitted when the Bluetooth service described by info is discovered.

Note

The passed QBluetoothServiceInfo parameter may contain a Bluetooth Low Energy service if the target device advertises the service via SDP. This is required from device which support both, classic Bluetooth (BaseRate) and Low Energy services.