# FiddlerCallbackHandler

> **Class** in `langchain_community`

📖 [View in docs](https://reference.langchain.com/python/langchain-community/callbacks/fiddler_callback/FiddlerCallbackHandler)

## Signature

```python
FiddlerCallbackHandler(
    self,
    url: str,
    org: str,
    project: str,
    model: str,
    api_key: str,
)
```

## Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `url` | `str` | Yes | Fiddler URL (e.g. https://demo.fiddler.ai). Make sure to include the protocol (http/https). |
| `org` | `str` | Yes | Fiddler organization id |
| `project` | `str` | Yes | Fiddler project name to publish events to |
| `model` | `str` | Yes | Fiddler model name to publish events to |
| `api_key` | `str` | Yes | Fiddler authentication token |

## Extends

- `BaseCallbackHandler`

## Constructors

```python
__init__(
    self,
    url: str,
    org: str,
    project: str,
    model: str,
    api_key: str,
) -> None
```

| Name | Type |
|------|------|
| `url` | `str` |
| `org` | `str` |
| `project` | `str` |
| `model` | `str` |
| `api_key` | `str` |


## Properties

- `fdl`
- `pd`
- `url`
- `org`
- `project`
- `model`
- `api_key`
- `run_id_prompts`
- `run_id_response`
- `run_id_starttime`
- `fiddler_client`
- `custom_features`

## Methods

- [`on_llm_start()`](https://reference.langchain.com/python/langchain-community/callbacks/fiddler_callback/FiddlerCallbackHandler/on_llm_start)
- [`on_llm_end()`](https://reference.langchain.com/python/langchain-community/callbacks/fiddler_callback/FiddlerCallbackHandler/on_llm_end)
- [`on_llm_error()`](https://reference.langchain.com/python/langchain-community/callbacks/fiddler_callback/FiddlerCallbackHandler/on_llm_error)

---

[View source on GitHub](https://github.com/langchain-ai/langchain-community/blob/4b280287bd55b99b44db2dd849f02d66c89534d5/libs/community/langchain_community/callbacks/fiddler_callback.py#L62)