MqttWildcardSubscription

Description

The MqttWildcardSubscription object subscribes to an MQTT wildcard topic specified in the name property and provides the received data in the data property. The names of all received topics are available in the topics property.

The parent object must be of type MqttClient.

This object was introduced in InCore 2.3.

› Inherits:

MqttAbstractSubscription

Overview

Properties

data dataType mode name topics updateTopics MqttAbstractSubscription.autoSubscribe

MqttAbstractSubscription.enabled MqttAbstractSubscription.error MqttAbstractSubscription.errorString MqttAbstractSubscription.qos MqttAbstractSubscription.subscribed Object.objectId Object.parent

Methods

mapDataObject() unmapDataObject() MqttAbstractSubscription.subscribe() MqttAbstractSubscription.unsubscribe()

Object.deserializeProperties() Object.fromJson() Object.serializeProperties() Object.toJson()

Signals

valueReceived() MqttAbstractSubscription.errorOccurred() Object.completed()

Enumerations

Mode MqttAbstractSubscription.Error

Properties

data

This property holds a map with the data of all topics matching the wildcard topic name.

› Type:

Map

› Signal:

dataChanged()

› Attributes:

Readonly

dataType

This property holds the data type which to convert the payload of incoming messages automatically. If not specified, the payload will not be converted and inserted as raw data in the data map or passed as raw data to the valueReceived() signal.

This property was introduced in InCore 2.4.

› Type:

DataObject.DataType

› Default:

DataObject.Invalid

› Signal:

dataTypeChanged()

› Attributes:

Writable

mode

This property holds the mode which specifies how to process incoming messages. See the MqttWildcardSubscription.Mode enumeration for details.

› Type:

Mode

› Default:

MqttWildcardSubscription.UpdateDataMap

› Signal:

modeChanged()

› Attributes:

Writable

name

This property holds the name of the wildcard topic to subscribe.

› Type:

String

› Signal:

nameChanged()

› Attributes:

Writable

topics

This property holds a list of names with all received topics matching the wildcard topic name.

› Type:

StringList

› Signal:

topicsChanged()

› Attributes:

Readonly

updateTopics

This property holds whether to update the topics property on every incoming message. If the topic list is not required, you can set this property to false to improve performance.

This property was introduced in InCore 2.7.

› Type:

Boolean

› Default:

true

› Signal:

updateTopicsChanged()

› Attributes:

Writable

Methods

mapDataObject(String topicName, DataObject dataObject)

This method registers the given DataObject instance to receive value for a certain topic name in the DataObject.data property directly.

This method was introduced in InCore 2.7.

unmapDataObject(DataObject dataObject)

This method removes the DataObject registration for a certain object.

This method was introduced in InCore 2.7.

Signals

valueReceived(String topicName, Variant value)

This signal is emitted whenever a new value has been received and mode is set to MqttWildcardSubscription.ReceiveValues. The name of the topic and the actual value are passed.

This signal was introduced in InCore 2.4.

Enumerations

Mode

This enumeration describes all supported modes for processing incoming messages

This enumeration was introduced in InCore 2.4.

Name	Value	Description
MqttWildcardSubscription.UpdateDataMap	0	Update the data map property. Use bindings to individual subproperties of the data property to use the actual data or react to xxxChanged() signals (see example).
MqttWildcardSubscription.ReceiveValues	1	Emits the valueReceived() signal on every incoming message. In this mode, the data map is not updated which can improve performance if you only need to process incoming (possibly converted) data value directly anyway.
MqttWildcardSubscription.WriteToDataOfMappedDataObjects	2	writes the received value to the DataObject.data property of the DataObject which has been associated with the respective topic name using the mapDataObject() method.
MqttWildcardSubscription.WriteToTimestampOfMappedDataObjects	3	writes the received value to the DataObject.timestamp property of the DataObject which has been associated with the respective topic name using the mapDataObject() method.

Example

import InCore.Foundation 2.5
import InCore.Mqtt 2.5

Application {
    MqttClient {
        clientId: "MqttWildcardSubscriptionExample"
        hostname: "localhost"

        MqttWildcardSubscription {
            id: allTopics
            name: "#"
            onTopicsChanged: console.log("Names of all published topics:", topics)
            property var counter: topics.includes("incore/foo/counter") ? parseInt(data.incore.foo.counter) : 0
            onCounterChanged: console.log("Counter:", counter)
        }
        MqttWildcardSubscription {
            name: "incore/+/date"
            dataType: MqttTopic.DateTime
            mode: MqttWildcardSubscription.ReceiveValues
            onValueReceived: console.log("Date:", value)
        }

        MqttWildcardSubscription {
            id: measurements
            dataType: MqttTopic.Float
            name: "measurements/#"
        }
    }

    ObjectArray {
        Repeater on objects {
            model: measurements.topics
            Measurement {
                objectId: modelData
                data: measurements.data[modelData]
                onDataChanged: console.log("Measurement value:", objectId, data)
            }
        }
    }
}