> For the complete documentation index, see [llms.txt](https://tabbli.gitbook.io/tabbli/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tabbli.gitbook.io/tabbli/working-with-sites/understanding-controllers.md).

# Understanding controllers

## General concept

Controllers are using for associate site's public URL with particular template.

![A list of controllers for particular site](/files/-LoP4m_avfIz0CVWu-2h)

Name of each template contains the site key and template file name itself separated by colon. For example, `tabbli:index.html`. If you need more flexible configuration (during development a solution template for example) you can specify site key as a variable: `{{site.key}}:index.html`.

![Controller options](/files/-LoPBzccngc4xRkzqD4y)

For each controller you should specify a url path. You can also use regular expressions for specify url patterns if you need not just single page but a set of dynamic pages. For example, you can use a pattern like `/products/(?P<key>[\w\d-]+)/` for crating controller which can generate a set of pages. In such case, corresponding url chunks associated with groups are available as global objects inside a template.

So, if you have such controller, which describes the parameter `key`, you can use the corresponding value inside the template for querying the data:

{% code title="product.html" %}

```markup
{% set product = DB(request)
    .get_collection('products').get_record(key, or404=True) %}
<h1>{{ product }}</h1>
```

{% endcode %}

Template name attribute can be also described as template. For example, your have the next templates which describes a number of pages:

* `docs/about_us.html`
* `docs/contacts.html`
* `docs/terms.html`
* `docs/privacy.html`

To make these pages public you do not need to create separate controllers for each template. You can create only one controller with url path pattern as `/docs/(?P<path>[\w\d-/]+)/` and then you can specify template name as `your_site:docs/{{path}}.html` . So, Tabbli will use different templates for different pages. If you try to open a page with unavailable corresponding template the 404 error will appairs.

## Additional options

You can also create use some extra options for setup access restrictions:

* **AJAX only** - make controller accessable obly via AJAX requests (in other case the "403 Response forbidden" error will be raised).
* **Allow loading via IFRAME** - change some server response HTTP headers for allowing to load the page via iframe on third-party domain (useful for widgets).
* **Login required** - make a redirect to the login page if a user is not logged in, so it block an access to the page for unauthorized users.