append-to-a-file.md

Append to a file

A transaction that appends new file content to the end of an existing file. The contents of the file can be viewed by submitting a FileContentsQuery request.

Transaction Signing Requirements

• The key on the file is required to sign the transaction if different than the client operator account key

Transaction Fees

• Please see the transaction and query fees table for base transaction fee
• Please use the Hedera fee estimator to estimate your transaction fee cost

Constructor	Description
FileAppendTransaction()	Initializes the FileAppendTransaction object

new FileAppendTransaction()

{% hint style="info" %} The default max transaction fee (1 hbar) is not enough to create a file. Use setMaxTransactionFee()to change the default max transaction fee from 1 hbar to 2 hbars. The default chunk size is 2,048 bytes. {% endhint %}

Methods

Method	Type	Description	Requirement
setFileId(<fileId>)	FileId	The ID of the file to append	Required
setContents(<text>)	String	The content in String format	Optional
setContents(<content>)	byte [ ]	The content in byte format	Optional
setChunkSize(<chunkSize>)	int	The chunk size	Optional
setMaxChunkSize(<maxChunks>)	int	The max chunk size	Optional

{% tabs %} {% tab title="Java" %}

//Create the transaction
FileAppendTransaction transaction = new FileAppendTransaction()
    .setFileId(newFileId)
    .setContents("The appended contents");

//Change the default max transaction fee to 2 hbars
FileCreateTransaction modifyMaxTransactionFee = transaction.setMaxTransactionFee(new Hbar(2)); 

//Prepare transaction for signing, sign with the key on the file, sign with the client operator key and submit to a Hedera network
TransactionResponse txResponse = modifyMaxTransactionFee.freezeWith(client).sign(key).execute(client);

//Request the receipt
TransactionReceipt receipt = txResponse.getReceipt(client);

//Get the transaction consensus status
Status transactionStatus = receipt.status;

System.out.println("The transaction consensus status is " +transactionStatus);

//v2.0.0

{% endtab %}

{% tab title="JavaScript" %}

//Create the transaction
const transaction = await new FileAppendTransaction()
    .setFileId(newFileId)
    .setContents("The appended contents")
    .setMaxTransactionFee(new Hbar(2))
    .freezeWith(client);

//Sign with the file private key
const signTx = await transaction.sign(fileKey);

//Sign with the client operator key and submit to a Hedera network
const txResponse = await signTx.execute(client);

//Request the receipt
const receipt = await txResponse.getReceipt(client);

//Get the transaction consensus status
const transactionStatus = receipt.status;

console.log("The transaction consensus status is " +transactionStatus);

//v2.0.5

{% endtab %}

{% tab title="Go" %}

//Create the transaction
transaction2 := hedera.NewFileAppendTransaction().
        SetFileID(newFileId).
        SetContents([]byte("The appended contents"))

//Change the default max transaction fee to 2 hbars
modifyMaxTransactionFee := transaction.SetMaxTransactionFee(hedera.HbarFrom(2, hedera.HbarUnits.Hbar))

//Prepare transaction for signing, 
freezeTransaction, err := modifyMaxTransactionFee.FreezeWith(client)
if err != nil {
        panic(err)
}

//Sign with the key on the file, sign with the client operator key and submit to a Hedera network
txResponse2 err := freezeTransaction.Sign(fileKey).Execute(client)
if err != nil {
        panic(err)
}

//Request the receipt
receipt, err := txResponse.GetReceipt(client)
if err != nil {
        panic(err)
}

//Get the transaction consensus status
transactionStatus := receipt.Status

fmt.Println("The transaction consensus status is ", transactionStatus)

//v2.0.0

{% endtab %} {% endtabs %}

Get transaction values

Method	Type	Description	Requirement
getFileId()	FileId	The file ID in the transaction	Optional
getContents()	String	The content in the transaction	Optional

{% tabs %} {% tab title="Java" %}

//Create the transaction
FileAppendTransaction transaction = new FileAppendTransaction()
    .setFileId(newFileId)
    .setContents("The appended contents");

//Get the contents
ByteString getContents = transaction.getContents();

//v2.0.0

{% endtab %}

{% tab title="JavaScript" %}

//Create the transaction
const transaction = new FileAppendTransaction()
    .setFileId(newFileId)
    .setContents("The appended contents");

//Get the contents
const getContents = transaction.getContents();

{% endtab %}

{% tab title="Go" %}

//Create the transaction
transaction2 := hedera.NewFileAppendTransaction().
    SetFileID(newFileId).
        SetContents([]byte("The appended contents"))

//Get the contents
getContents2 := transaction2.GetContents()

//v2.0.0

{% endtab %} {% endtabs %}