Get topic messages

Subscribe to a topic ID's messages from a mirror node. You will receive all messages for the specified topic or within the defined start and end time.
V2
V1
Constructor
Description
new TopicMessageQuery()
Initializes the TopicMessageQuery object
1
new TopicMessageQuery()
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Methods
Method
Type
Description
Requirement
setTopicId(<topicId>)
TopicId
The topic ID to subscribe 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
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//Create the query
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new TopicMessageQuery()
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    .setTopicId(newTopicId)
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    .subscribe(client, topicMessage -> {
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        System.out.println("at " + topicMessage.consensusTimestamp + " ( seq = " + topicMessage.sequenceNumber + " ) received topic message of " + topicMessage.contents.length + " bytes");
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    });
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​
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//v2.0.0
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JavaScript
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//Create the query
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new TopicMessageQuery()
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        .setTopicId(topicId)
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        .setStartTime(0)
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        .subscribe(
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            client,
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            (message) => console.log(Buffer.from(message.contents, "utf8").toString())
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        );
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//v2.0.0
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Go
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//Create the query
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_, err = hedera.NewTopicMessageQuery().
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    SetTopicID(topicID).
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    Subscribe(client, func(message hedera.TopicMessage) {
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        if string(message.Contents) == content {
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        wait = false
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    }
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})
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​
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if err != nil {
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    panic(err)
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}
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​
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//v2.0.0
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Constructor
Description
new MirrorConsensusTopicQuery()
Initializes the MirrorConsensusTopicQuery object
1
new MirrorConsensusTopicQuery()
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Methods
Method
Type
Description
Requirement
setTopicId(<topicId>)
TopicId
The topic ID to subscribe 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
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new MirrorConsensusTopicQuery()
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    .setTopicId(topicId)
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    .subscribe(mirrorClient, resp -> {
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                String messageAsString = new String(resp.message, StandardCharsets.UTF_8);
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​
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                System.out.println(resp.consensusTimestamp + " received topic message: " + messageAsString);
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            },
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            // On gRPC error, print the stack trace
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            Throwable::printStackTrace);
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//v1.3.2
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JavaScript
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new MirrorConsensusTopicQuery()
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    .setTopicId(topicId)
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    .subscribe(
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        consensusClient,
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        (message) => console.log(message.toString()),
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        (error) => console.log(`Error: ${error}`)
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    );
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Delete a topic

Get topic info

Last modified 3mo ago

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