Get topic info

Topic info returns 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.
Ledger ID	The ID of the network the response came from. See HIP-198.
Fee Schedule Key	The key that is authorized to modify the fee structure for submitting messages to this topic. If present, this key must be used to update the topic’s fee settings. If absent, the topic’s fee structure cannot be changed.
Fee Exempt Key	A list of accounts that do not have to pay a fee when submitting messages to the topic. If this field is present, it means certain accounts are allowed to submit messages for free. If absent, no exemptions exist.
Fee Schedule	The current fee structure that applies to message submissions for this topic. It specifies the amount charged per message, which can be denominated in HBAR or a chosen fungible token. If this field is present, the topic enforces fees for message submissions; if absent, message submission is free.

Query Signing Requirements

• The client operator private key is required to sign the query request

Query Fees

• Please see the transaction and query fees table for the base transaction fee

• Please use the Hedera fee estimator to estimate your query fee cost

Method	Type	Requirement
setTopicId(<topicId>)	TopicId	Required
<TopicInfo>.adminKey	Key	Optional
<TopicInfo>.submitKey	Key	Optional
<TopicInfo>.topicId	TopicId	Optional
<TopicInfo>.sequenceNumber	long	Optional
<TopicInfo>.runningHash	ByteString	Optional
<TopicInfo>.memo	String	Optional
<TopicInfo>.ledgerId	LedgerId	Optional
<TopicInfo>.expirationTime	Instant	Optional
<TopicInfo>.autoRenewAccount	AccountId	Optional
<TopicInfo>.autoRenewPeriod	Instant	Optional

Java

//Create the account info query
TopicInfoQuery query = new TopicInfoQuery()
    .setTopicId(newTopicId);

//Submit the query to a Hedera network
TopicInfo info = query.execute(client);

//Retrieve additional HIP-991 fields
Key feeScheduleKey = info.getFeeScheduleKey();
List<CustomFee> customFees = info.getCustomFees();
List<Key> feeExemptKeys = info.getFeeExemptKeyList();

//Print the account key to the console
System.out.println(info);
System.out.println("Fee Schedule Key: " + feeScheduleKey);
System.out.println("Custom Fees: " + customFees);
System.out.println("Fee Exempt Key List: " + feeExemptKeys);

//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);

//Retrieve additional HIP-991 fields
const feeScheduleKey = info.feeScheduleKey;
const customFees = info.customFees;
const feeExemptKeys = info.feeExemptKeyList;

//Print the account key to the console
console.log(info);
console.log("Fee Schedule Key:", feeScheduleKey);
console.log("Custom Fees:", customFees);
console.log("Fee Exempt Key List:", feeExemptKeys);

//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)
}

//Retrieve additional HIP-991 fields
feeScheduleKey := info.GetFeeScheduleKey()
customFees := info.GetCustomFees()
feeExemptKeys := info.GetFeeExemptKeyList()

//Print the account key to the console
println(info)
fmt.Println("Fee Schedule Key:", feeScheduleKey)
fmt.Println("Custom Fees:", customFees)
fmt.Println("Fee Exempt Key List:", feeExemptKeys)

//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
}