notes / multi website
github: jorenvo | email: joren@jvo.sh | PGP: 50A5 7A39 0DE1 1A6C | keybase: jvo

Multi-website in Odoo v12

The goal of this document is to give a thorough technical understanding of the standard multi-website feature in ≥v12. I will be focusing on v12 in this document, but everything should be applicable to v13 as well.

1 Website selection

What website to render is determined by get_current_website(). It matches websites based on their domain name and possibly geoip. This is also the function that should be used when you want to determine the website you're on in Python.

Odoo can be forced to load a specific website, regardless of the current domain or geoip via the website selector in the frontend:

website_selector.png

You can also do it manually with this GET parameter:

?fw=2

This is set on the session so it will persist as long as the user is logged in. See this for more info on sessions.

2 Copy-on-write (COW)

Multi-website is implemented in a way that keeps module upgrades and migrations easy. If a bug fix in a view is merged it makes sure that this view change is applied to all websites. It also makes sure that we retain the ability for a user to create a brand new, unmodified website at all times (with e.g. an unmodified Contact Us page).

When naively duplicating views for each website you clutter the database with a lot of unnecessary records. In most cases Odoo will use a copy-on-write mechanism. It defers duplicating views until necessary. Views are created without a website_id and rendered as usual. When a user modifies a view a website specific copy is created with the appropriate website_id and the same key. This only happens for writes that happen via the frontend (not in /web). With this mechanism bug fixes to non-edited views are applied as usual and newly created websites will contain all the necessary views. Also this way we keep the original views without a website_id which can be used for new websites. The key field mentioned above is used instead of the XML ID, since multiple records with the same XML ID are not allowed.

From a technical POV this is mostly implemented in the write of ir.ui.view in the website module, note that it will also handle:

  • creating website-specific inherited views if they exist,
  • creating website-specific inactive views (used for customize_show_views),
  • creating website-specific pages for these views,

On top of this there is a mechanism that duplicates writes during module updates. It's implemented in _load_records_write(). During a module upgrade it will duplicate view writes to website-specific views. This only happens when the field on the website-specific view was not edited. This means that fixes can be applied to COWed views, but only in the rare case where the field value being updated does not differ from the original value. For example: if a view was COWed because arch_db was updated then no bug fixes to arch_db will be copied over but bug fixes to access rights still will.

For unlinking a Copy-on-unlink is implemented. Website-specific copies are created when a generic view is deleted from the frontend.

2.1 Rendering

When views are rendered filter_duplicate() ensures that for each key a website specific view is preferred over a generic one if it exists. Here's an example:

inheritance.png

The label in each node corresponds to the key of the view. If a website_id is configured it's shown between square brackets. The arrow defines inherit_id, so child views point to their parents.

When website 1 is rendered it will consist of:

  • website.layout
  • website.layout_logo_show [website 1] (this view can be inactive)
  • website.sale_header
  • custom.sale_header

A render of website 2 will consist of:

  • website.layout
  • website.layout_logo_show [website 2] (this view can be inactive)
  • website.sale_header
  • theme_treehouse.preheader [website 2]

3 Mixins

Multiple mixins are available to publish models on the website:

3.1 website.published.multi.mixin

This inherits both website.published.mixin and website.multi.mixin and is probably what you want to use in most cases. It allows records in a model to be published on all or one website. When rendering a QWeb view on the website make sure to wrap it in website.layout and set main_object in the rendering context. It should be the main record you're rendering, the website module will use this record to make the publish/unpublish feature work:

published_unpublished.png

Unfortunately you need to manually check in your controllers whether or not the record is accessible from the current website. This mixin provides can_access_from_current_website() for that:

from werkzeug.exceptions import NotFound
# ...
if not record.can_access_from_current_website():
    raise NotFound()

3.2 website.published.mixin

This makes it possible to publish/unpublish your model through website_publish_button(). It only supports publishing your record on all websites. Records using this will also be publishable from the website via the toggle.

3.3 website.multi.mixin

In practice this only provides a website_id field and the can_access_from_current_website() function. Use this if you want to restrict the visibility of records to one specific website, but you don't want users to be able to publish/unpublish these records themselves via the frontend.

4 Record rule

website is added to the eval context of record rules so you can easily write record rules that restrict based on the current website:

<record id="my_record_rule" model="ir.rule">
    <field name="name">Show only on website 2</field>
    <field name="model_id" ref="model_custom_model"/>
    <field name="global" eval="True"/>
    <field name="domain_force">[("website_id", "=", website.id)]</field>
</record>

5 Themes

Themes are regular Odoo modules but they are more complex than you might expect. They have both upstream and downstream dependencies. An upstream dependency is a module the theme directly or indirectly depends on. E.g. theme_common, theme_loftspace and theme_beauty for theme_beauty_sale. Downstream dependencies are modules that depend on it. As you may have noticed above: themes can depend on other themes. Themes can activate optional features on the website by activating website_sale views (e.g. website_sale.categories to activate eCommerce categories). Themes also have their own ir.attachment records which contain default images and other themes that depend on them can modify them. Lastly, themes are often auto-installed (e.g. theme_*_sale modules when website_sale is installed).

It leads to complex scenarios. Imagine theme B depends on theme A. The user has installed theme A on website A and theme B on website B. If theme A is uninstalled on website A it cannot be fully removed because it would break website B.

Because of all this complexity themes are handled in a special way. Only relying on COW is too complex so instead data related to themes is stored in template models:

  • theme.ir.ui.view
  • theme.ir.attachment
  • theme.website.menu
  • theme.website.page

When themes are installed these template models are converted to their normal counterparts with _convert_to_base_model(). Each one of these will have a website_id and a theme_template_id to link them back to the theme.

You can upgrade a theme on all websites with odoo-bin -u or upgrade a theme on only one website via the backend by going to the website's URL.

6 Sessions

Sessions are based on Werkzeug sessions. When a user visits Odoo a session cookie is created and stored in their browser. It's a unique ID that links every requests that browser makes to a session in Odoo. On the server side the session is persistent and is written to disk (by default ~/.local/share/Odoo/sessions/). It contains data different data that needs to persist (e.g. whether or not the user is logged in). The session files are pickled, if you want to inspect them you can use:

$ python3 -m pickle ~/.local/share/Odoo/sessions/werkzeug_861d25cb*.sess

Stale sessions are automatically removed. A session is considered stale if it hasn't been modified for one week. The expiration date for the cookie on the browser side is 3 months. This is why after 3 months you need to login again.

7 Assets

JS and SCSS assets in Odoo are compiled, minimized and combined into asset bundles. In the case of SCSS it's a necessary step; it needs to be compiled to CSS for the browser to understand. But this is not the only reason, reducing the number of files the browser needs to load also reduces the amount of HTTP requests. On top of that the minimization reduces the file size which speeds up each HTTP request. To skip the minimization and bundling you can use ?debug=assets. It's useful when working on the frontend and also demonstrates how much faster the asset bundling process makes Odoo.

Each bundle is a single file, saved as an ir.attachment record. You can find them like this:

SELECT id, url
FROM ir_attachment
WHERE name LIKE '/web/content%'
ORDER BY id;

New bundles are defined in templates as regular QWeb templates and called in the appropriate locations as follows:

<t t-call-assets="web.assets_common"...

This leads to _get_asset_nodes() being called which eventually calls get_asset_bundle(). This creates objects that inherit from AssetsBundle (like JavascriptAsset and StylesheetAsset). The unique key of the asset is computed in the checksum property and is a hash of:

  • the metadata (filename, type, url, …) of the files it contains, and
  • the last time a file in the asset bundle was modified

This causes recompilation of an asset bundle when a file in it changes or new files are added. This checksum is saved in the URL of the ir.attachment and looks like this:

/web/content/1002-0d0afe0/web.assets_common.js

  • 1002: the ir.attachment ID
  • 0d0afe0: the first 7 characters of the checksum

This leads to issues with >1 website, because every website will have its own assets. To avoid the assets constantly recompiling the website module adds the website ID to the URL:

/web/content/1012-0d0afe0/2/web.assets_common.0.js

  • 2: the website ID

This allows Odoo to maintain separate compiled asset bundles per website.

Emacs 26.1 (Org mode 9.1.9)

Published on May 14 2020