Get topic messages

Subscribe to a topic ID's messages from a mirror node. You will recieve all messages for the specified topic or within the defined start and end time.
V2
V1
V2
Constructor
Description
new TopicMessageQuery()
Initializes the TopicMessageQuery object
new TopicMessageQuery()
Methods
Method
Type
Description
Requirement
setTopicId(<topicId>)
TopicId
The topic ID to subsribe to
Required
setStartTime(<startTime>)
Instant
The time to start subscribing to a topic's messages
Optional
setEndTime(<endTime>)
Instant
The time to stop subscribing to a topic's messages
Optional
setLimit(<limit>)
long
The number of messages to return
Optional
subscribe(<client, onNext)
SubscriptionHandle
Client, Consumer<TopicMessage>
Required
Java
//Create the query
new TopicMessageQuery()
    .setTopicId(newTopicId)
    .subscribe(client, topicMessage -> {
        System.out.println("at " + topicMessage.consensusTimestamp + " ( seq = " + topicMessage.sequenceNumber + " ) received topic message of " + topicMessage.contents.length + " bytes");
    });
​
//v2.0.0
JavaScript
//Create the query
new TopicMessageQuery()
        .setTopicId(topicId)
        .setStartTime(0)
        .subscribe(
            client,
            (message) => console.log(Buffer.from(message.contents, "utf8").toString())
        );
//v2.0.0
Go
//Create the query
_, err = hedera.NewTopicMessageQuery().
	SetTopicID(topicID).
	Subscribe(client, func(message hedera.TopicMessage) {
		if string(message.Contents) == content {
		wait = false
	}
})
​
if err != nil {
	panic(err)
}
​
//v2.0.0
V1
​
Constructor
Description
new MirrorConsensusTopicQuery()
Initializes the MirrorConsensusTopicQuery object
new MirrorConsensusTopicQuery()
Methods
Method
Type
Description
Requirement
setTopicId(<topicId>)
TopicId
The topic ID to subsribe to
Required
setStartTime(<startTime>)
Instant
The time to start subscribing to a topic's messages
Optional
setEndTime(<endTime>)
Instant
The time to stop subscribing to a topic's messages
Optional
setLimit(<limit>)
long
The number of messages to return
Optional
subscribe(<mirrorClient,
onNext onError)
MirrorClient, Consumer
<MirrorConsensusTopicResponse>, Consumer<Throwable>
Subscribe and get the  messages for a topic
Required
Java
new MirrorConsensusTopicQuery()
    .setTopicId(topicId)
    .subscribe(mirrorClient, resp -> {
                String messageAsString = new String(resp.message, StandardCharsets.UTF_8);
​
                System.out.println(resp.consensusTimestamp + " received topic message: " + messageAsString);
            },
            // On gRPC error, print the stack trace
            Throwable::printStackTrace);
//v1.3.2
JavaScript
new MirrorConsensusTopicQuery()
    .setTopicId(topicId)
    .subscribe(
        consensusClient,
        (message) => console.log(message.toString()),
        (error) => console.log(`Error: ${error}`)
    );
​

Delete a topic

Get topic info

Last updated 4 months ago

Constructor	Description
`new TopicMessageQuery()`	Initializes the TopicMessageQuery object

Method	Type	Description	Requirement
`setTopicId(<topicId>)`	TopicId	The topic ID to subsribe to	Required
`setStartTime(<startTime>)`	Instant	The time to start subscribing to a topic's messages	Optional
`setEndTime(<endTime>)`	Instant	The time to stop subscribing to a topic's messages	Optional
`setLimit(<limit>)`	long	The number of messages to return	Optional
`subscribe(<client, onNext)`	SubscriptionHandle	Client, Consumer<TopicMessage>	Required

Constructor	Description
`new MirrorConsensusTopicQuery()`	Initializes the MirrorConsensusTopicQuery object

Get topic messages

Methods

Methods

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