> For the complete documentation index, see [llms.txt](https://rsyi.gitbook.io/whale/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://rsyi.gitbook.io/whale/features/jinja2-templating.md).

# Jinja2 templating

{% hint style="info" %}
**Supported connections:** BigQuery, Postgres, Presto, Redshift, Snowflake
{% endhint %}

All metrics calculations and executed SQL queries will be passed through the Jinja2 engine, so any basic Jinja2 templating, as you might expect, is supported. If you're not familiar with Jinja2, a basic example is shown below.

```
{% set table = census.public_data %}
select count(*) from {{ table }}
```

## Reusable templates

On top of this, we provide support for **reusable templates**, which should be saved in the `~/.whale/templates` folder  and **named after the name of the warehouse connection that you would like to use this template for**. Connection names can be found by running `wh connections`, in the `name` field of each yaml block. 

```
.whale
└── templates
    └── warehouse-connection-name.sql
```

For example, consider the following BigQuery connection setup:

```
---
name: bq-1
metadata_source: Bigquery
key_path: ~
project_credentials: ~
project_id: my-bigquery-project
```

The name of the connection here is `bq-1`, so you'll need to create a file as follows:

```
.whale
└── templates
    └── bq-1.sql
```

And the template within will automatically be pre-pended to queries against this connection.

## Template example

The following snippet enables the value `{{ last_day }}` to be used to performantly get data from the latest partition in BigQuery.

```
{% set last_day = "_PARTITIONDATE = DATE_SUB(CURRENT_DATE(), INTERVAL 1 DAY)" %}
```

The following query, then, could be run by `whale`:

```
select count(*) from table.schema where {{ last_day }}
```