# BigQueryLoader

> **Class** in `langchain_google_community`

📖 [View in docs](https://reference.langchain.com/python/langchain-google-community/bigquery/BigQueryLoader)

Load documents from Google Cloud BigQuery.

Inherits from [`BaseLoader`][langchain_core.document_loaders.BaseLoader].

Each row becomes a document. Columns can be mapped to `page_content` or
`metadata`. By default, all columns map to `page_content`.

!!! note "Installation"

    Requires additional dependencies:

    ```bash
    pip install langchain-google-community[bigquery]
    ```

## Signature

```python
BigQueryLoader(
    self,
    query: str,
    project: Optional[str] = None,
    page_content_columns: Optional[List[str]] = None,
    metadata_columns: Optional[List[str]] = None,
    credentials: Optional[Credentials] = None,
)
```

## Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `query` | `str` | Yes | The query to run in BigQuery. |
| `project` | `Optional[str]` | No | Optional. The project to run the query in. (default: `None`) |
| `page_content_columns` | `Optional[List[str]]` | No | Optional. The columns to write into the `page_content` of the document. (default: `None`) |
| `metadata_columns` | `Optional[List[str]]` | No | Optional. The columns to write into the `metadata` of the document. (default: `None`) |
| `credentials` | `Optional[Credentials]` | No | Optional. Credentials for accessing Google APIs. Use this parameter to override default credentials, such as to use Compute Engine (`google.auth.compute_engine.Credentials`) or Service Account (`google.oauth2.service_account.Credentials`) credentials directly. (default: `None`) |

## Extends

- `BaseLoader`

## Constructors

```python
__init__(
    self,
    query: str,
    project: Optional[str] = None,
    page_content_columns: Optional[List[str]] = None,
    metadata_columns: Optional[List[str]] = None,
    credentials: Optional[Credentials] = None,
)
```

| Name | Type |
|------|------|
| `query` | `str` |
| `project` | `Optional[str]` |
| `page_content_columns` | `Optional[List[str]]` |
| `metadata_columns` | `Optional[List[str]]` |
| `credentials` | `Optional[Credentials]` |


## Properties

- `query`
- `project`
- `page_content_columns`
- `metadata_columns`
- `credentials`

## Methods

- [`load()`](https://reference.langchain.com/python/langchain-google-community/bigquery/BigQueryLoader/load)

---

[View source on GitHub](https://github.com/langchain-ai/langchain-google/blob/982e4015b249de8b9ba1e787746d8cc1f6d6b790/libs/community/langchain_google_community/bigquery.py#L22)