# Automatically insert data into a reStructuredText file

## Objective

Suppose you need to present three products: *Dianthus*, *Geum*, and *Prunus*, each available in versions *1.0*, *1.5*, and *2.3*.

Instead of manually entering data into the content file, you can automate this process using Jinja and Python — the same templating engine used for [conditional text profiling](https://docs.redaction-technique.org/en/tutorials/conditional-text-jinja/).

1. Create the following `template.rst` file:

    ```rst
    Products and Versions
    =====================
    {% for prod in products %}
    {{ prod | capitalize }}
    {% for c in prod %}-{% endfor %}
       {% for ver in versions %}
    - {{ ver }}
       {% endfor %}
    {% endfor %}
    ```

2. Create the following Python script `populate.py`:

    ```python
    #!/usr/bin/python
    # coding: utf-8
    import jinja2
    
    env = jinja2.Environment(loader=jinja2.FileSystemLoader('./'), lstrip_blocks=True)
    
    template = env.get_template('template.rst')
    
    data = {
        'products': ['dianthus', 'geum', 'prunus'],
        'versions': ['1.0', '1.5', '2.3']
    }
    print(template.render(data))
    ```

3. Make the script executable, then run it:

    ```bash
    chmod +x populate.py
    ./populate.py
    ```

    The following output is displayed:

    ```md
    Products and Versions
    =====================

    Dianthus
    --------

    - 1.0

    - 1.5

    - 2.3

    Geum
    ----

    - 1.0

    - 1.5

    - 2.3

    Prunus
    ------

    - 1.0

    - 1.5

    - 2.3
    ```

This approach minimizes the risk of errors and reduces the effort involved in updating.

## Related articles

- [Create different documents from the same sources via Jinja (object method)](https://docs.redaction-technique.org/en/tutorials/conditional-text-jinja-object-method/)
- [Regular expressions in Python](https://docs.redaction-technique.org/en/tutorials/python-regular-expressions/)
- [The Raspberry Pi 3 as a documentation platform](https://docs.redaction-technique.org/en/tutorials/raspberry-pi-documentation-platform/)
- [Auto-insert data into a DITA XML file](https://docs.redaction-technique.org/en/tutorials/auto-insert-data-dita-xml/)
- [Automatically insert SQL data into a reStructuredText file](https://docs.redaction-technique.org/en/tutorials/auto-insert-sql-data-restructuredtext/)

## Related reading

- [Boost documentation efficiency: how YAML outperforms XML, Markdown, and databases](https://redaction-technique.org/scalable-maintainable-technical-docs-with-yaml) — driving documents from structured YAML data.

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Source: https://docs.redaction-technique.org/en/tutorials/auto-insert-data-restructuredtext/