Get topic info

Topic info returns the the following values for a topic.  Queries do not change the state of the topic or require network consensus. The information is returned from a single node processing the query.
Topic Info Response:
Field
Description
Topic ID
The ID of the topic
Admin Key
Access control for update/delete of the topic. Null if there is no key.
Submit Key
Access control for ConsensusService.submitMessage. Null if there is no key.
Sequence Number
Current sequence number (starting at 1 for the first submitMessage) of messages on the topic.
Running Hash
SHA-384 running hash 
Expiration Time
Effective consensus timestamp at (and after) which submitMessage calls will no longer succeed on the topic and the topic will expire and be marked as deleted.
Topic Memo
Short publicly visible memo about the topic. No guarantee of uniqueness.
Auto Renew Period
The lifetime of the topic and the amount of time to extend the topic's lifetime by
Auto Renew Account
Null if there is no autoRenewAccount. 
Query Signing Requirements
The client operator private key is required to sign the query request
V2
V1
V2
Constructor
Description
new TopicInfoQuery()
Initializes the TopicInfoQuery object
new TopicInfoQuery()
Method
Type
Description
Requirement
setTopicId(<topicId>)
TopicId
The ID of the topic to get information for
Required
Java
//Create the account info query
TopicInfoQuery query = new TopicInfoQuery()
    .setTopicId(newTopicId);
​
//Submit the query to a Hedera network
TopicInfo info = query.execute(client);
​
//Print the account key to the console
System.out.println(info);
​
//v2.0.0
JavaScript
//Create the account info query
const query = new TopicInfoQuery()
    .setTopicId(newTopicId);
​
//Submit the query to a Hedera network
const info = await query.execute(client);
​
//Print the account key to the console
console.log(info);
​
//v2.0.0
Go
//Create the account info query
query, err := hedera.NewTopicInfoQuery().
		SetTopicID(topicID)
​
//Submit the query to a Hedera network
info, err := query.Execute(client)
if err != nil {
		panic(err)
}
​
//Print the account key to the console
println(info)
​
//v2.0.0
Sample Output:
TopicInfo{
     topicId=0.0.102736, 
     topicMemo=, 
     runningHash=[ 
          0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,            0. 0, 0,0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0
     ], 
     sequenceNumber=0, 
     expirationTime=2021-02-09T03:17:07.258292001Z, 
     adminKey=null, 
     submitKey=null, 
     autoRenewPeriod=PT2160H, 
     autoRenewAccountId=null
}
V1
Constructor
Description
new ConsensusTopicInfoQuery()
Initializes the ConsensusTopicInfoQuery object
new ConsensusTopicInfoQuery()
​
Method
Type
Description
Requirement
setTopicId(<topicId>)
TopicId
The ID of the topic to get information for
Required
Java
//Create the account info query
TopicInfoQuery query = new ConsensusTopicInfoQuery()
    .setTopicId(newTopicId);
​
//Submit the query to a Hedera network
TopicInfo info = query.execute(client);
​
//Print the account key to the console
System.out.println(info);
​
//v1.3.2
JavaScript
//Create the account info query
const query = new ConsensusTopicInfoQuery()
    .setTopicId(newTopicId);
​
//Submit the query to a Hedera network
const info = await query.execute(client);
​
//Print the account key to the console
console.log(info);
​
//v1.4.4
​

Get topic messages

Errors

Last updated 4 months ago

Field	Description
Topic ID	The ID of the topic
Admin Key	Access control for update/delete of the topic. Null if there is no key.
Submit Key	Access control for ConsensusService.submitMessage. Null if there is no key.
Sequence Number	Current sequence number (starting at 1 for the first submitMessage) of messages on the topic.
Running Hash	SHA-384 running hash
Expiration Time	Effective consensus timestamp at (and after) which submitMessage calls will no longer succeed on the topic and the topic will expire and be marked as deleted.
Topic Memo	Short publicly visible memo about the topic. No guarantee of uniqueness.
Auto Renew Period	The lifetime of the topic and the amount of time to extend the topic's lifetime by
Auto Renew Account	Null if there is no autoRenewAccount.

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

Method	Type	Description	Requirement
`setTopicId(<topicId>)`	TopicId	The ID of the topic to get information for	Required

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