> For the complete documentation index, see [llms.txt](https://abc.bharatblockchain.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://abc.bharatblockchain.io/hedera/tutorials/file-service/retrieve-file.md).

# Retrieve File

This script retrieves the contents of a file stored on the Hedera network using a file ID, saves it locally, and logs the size of the retrieved data to the console. It demonstrates how to use the `FileContentsQuery` to fetch file contents and perform file operations with Hedera.

## Step 1: Imports

* The script imports necessary modules from the Hedera JavaScript SDK (`@hashgraph/sdk`): `FileContentsQuery`, `LocalProvider`, and `Wallet`.
* It also imports the `fs` module from Node.js for file system operations, and the `exit` method from the `process` module.

```javascript
const {
    FileContentsQuery,
    LocalProvider,
    Wallet
} = require("@hashgraph/sdk");
const fs = require('fs');
const { exit } = require("process");
```

## Step 2: Environment Variables Retrieval and Validation

* The script loads environment variables from a `.env` file located in the `File_Service` directory using `dotenv`.
* It checks whether the required environment variables (`MY_ACCOUNT_ID` and `MY_PRIVATE_KEY`) are present. If not, it throws an error.
* It retrieves the file ID (`FILE_ID`) from the environment variables.

```javascript
require('dotenv').config({ path: 'File_Service/.env' });

if (process.env.MY_ACCOUNT_ID == null || process.env.MY_PRIVATE_KEY == null) {
    throw new Error(
        "Environment variables OPERATOR_ID, and OPERATOR_KEY are required."
    );
}

const fileId = process.env.FILE_ID;
```

## Step 3: Wallet Initialization

* It creates a new `Wallet` instance using the account ID and private key retrieved from the environment variables.
* The wallet is initialized with a `LocalProvider`, indicating that it will be used for local signing of transactions.

```javascript
const wallet = new Wallet(
    process.env.MY_ACCOUNT_ID,
    process.env.MY_PRIVATE_KEY,
    new LocalProvider()
);
```

## Step 4 : Main Function

* It creates a new `FileContentsQuery` object to retrieve the contents of the file specified by the file ID.
* The file ID is set using the value retrieved from the environment variables.
* The query is executed with the signer (wallet) to retrieve the contents of the file.
* The size of the retrieved data is logged to the console.
* The retrieved contents are then written to a local file named `hedera-retrieved.pdf` in the `File_Service` directory using `fs.writeFileSync()`.
* Finally, the script exits the process.

```javascript
async function main() {
    const query = new FileContentsQuery()
        .setFileId(fileId); // Set the file ID to retrieve its contents

    const contents = await query.executeWithSigner(wallet); // Execute the query with signer

    console.log(`The size of the data is ${contents.length}`);

    fs.writeFileSync('File_Service/hedera-retrieved.pdf', contents); // Write the retrieved contents to a local file

    process.exit(); // Exit the process
}

```

## Step 5: Execution

This line calls the `main()` function to start the execution of the script.

```javascript
main();
```