# on\_get\_block\_hash - Monero

This method returns the block hash at a given block height. Note the positional `params` array (a single-element array containing the height), not the usual object form.

## Parameters

| Parameter  | Type         | Required | Description             |
| ---------- | ------------ | -------- | ----------------------- |
| params\[0] | unsigned int | Yes      | Block height to look up |

## Request Example

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

```bash
curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "on_get_block_hash",
    "params": [
        912345
    ],
    "id": "getblock.io"
}'
```

{% endtab %}

{% tab title="JavaScript (Axios)" %}

```javascript
import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "on_get_block_hash",
    "params": [
        912345
    ],
    "id": "getblock.io"
});

const config = {
    method: 'post',
    url: 'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers: {
        'Content-Type': 'application/json'
    },
    data: data
};

axios(config)
    .then(response => console.log(JSON.stringify(response.data, null, 2)))
    .catch(error => console.log(error));
```

{% endtab %}

{% tab title="Python (Requests)" %}

```python
import requests
import json

url = "https://go.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "on_get_block_hash",
    "params": [
        912345
    ],
    "id": "getblock.io"
})

headers = {
    'Content-Type': 'application/json'
}

response = requests.post(url, headers=headers, data=payload)
print(response.text)
```

{% endtab %}

{% tab title="Rust (Reqwest)" %}

```rust
use reqwest::Client;
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let payload = json!({
        "jsonrpc": "2.0",
        "method": "on_get_block_hash",
        "params": [
                912345
        ],
        "id": "getblock.io"
});

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&payload)
        .send()
        .await?;

    let result: serde_json::Value = response.json().await?;
    println!("{:#?}", result);

    Ok(())
}
```

{% endtab %}
{% endtabs %}

## Response Example

{% code overflow="wrap" %}

```json
{
    "id": "getblock.io",
    "jsonrpc": "2.0",
    "result": "e22cf75f39ae720e8b71b3d120a5ac03f0db50bba6379e2850975b4859190bc6"
}
```

{% endcode %}

## Response Parameters

| Field  | Type   | Description                    |
| ------ | ------ | ------------------------------ |
| result | string | Block hash at the given height |

## Use Cases

* Resolving height to hash for historical queries
* Cursor-based pagination through historical blocks
* Bridging height-based and hash-based block references

## Error Handling

| Status Code | Error Message     | Cause                                       |
| ----------- | ----------------- | ------------------------------------------- |
| 404         | Not Found         | Missing or invalid `<ACCESS-TOKEN>`         |
| -32602      | Invalid params    | Request parameters are missing or malformed |
| 429         | Too Many Requests | Rate limit exceeded for your plan           |

## SDK Integration

{% tabs %}
{% tab title="monero-javascript" %}

```javascript
import monerojs from 'monero-javascript';

const daemon = await monerojs.connectToDaemonRpc('https://go.getblock.io/<ACCESS-TOKEN>/');

// Most methods are exposed directly on the daemon client. For raw access:
const result = await daemon.getDaemonConnection().sendJsonRequest('on_get_block_hash', [912345]);
console.log(result);
```

{% endtab %}

{% tab title="monero-python" %}

```python
from monero.backends.jsonrpc import JSONRPCDaemon
from monero.daemon import Daemon

backend = JSONRPCDaemon(host='go.getblock.io', port=443, path='/<ACCESS-TOKEN>/', protocol='https')
daemon = Daemon(backend)

# For methods covered by the typed API, use the daemon attribute directly.
# For raw RPC access:
result = backend.raw_request('on_get_block_hash', [912345])
print(result)
```

{% endtab %}
{% endtabs %}


---

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Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.getblock.io/api-reference/monero-xmr/on_get_block_hash-monero.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

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