Alias

The “Alias” attribute generates a unique, URL-compatible short identifier derived from one or more existing attributes. Typical use cases:

URL parameters in frontend filtering (e.g. /products/my-product)
Readable, stable identifiers for deep links or SEO URLs
Unique slugs automatically generated from names or titles

The alias is automatically composed from the configured source attributes when saving a record. A character set and a conversion language can be specified so that special characters (e.g. umlauts) are correctly converted.

Note

An alias is not automatically unique. To ensure uniqueness, the “Unique values” option must be enabled in the general attribute settings.

Warning

If the “Force alias regeneration” option is enabled, existing alias values will be regenerated every time the source attributes change. This may invalidate already-published URLs.

Installation

The attribute is installed via the Contao Manager or Composer:

composer require metamodels/attribute_alias

Settings when Creating the Attribute

In addition to the general attribute settings (name, column name, description, unique values, override variants), the alias attribute offers the following specific options:

Alias Fields

Option	Description
Alias fields	Selection of one or more attributes from which the alias is built. In addition to MetaModels attributes, system meta fields such as ID, PID, sorting, or timestamp are also available. If multiple fields are selected, their values are joined with a hyphen.

Generation and Character Set

Option	Description
Force alias regeneration	If this checkbox is enabled, the alias is automatically regenerated every time one of the source attributes changes. The alias field is then displayed as read-only in the backend. Without this option, a once-generated alias remains unchanged.
Valid alias characters	Defines which character set is used for automatic generation. Possible values: Unicode digits and lowercase letters (default), Unicode digits and letters, ASCII digits and lowercase letters, ASCII digits and letters.
Conversion language	ISO 639-1 language code (e.g. `de` or `de-DE`) used to convert special characters during generation. If left empty, the default conversion is used.
Alias prefix	Optional text prepended to the generated alias (only alphanumeric characters allowed).
Alias postfix	Optional text appended to the generated alias.
No integer prefix	If this checkbox is active (default), no `id-` prefix is prepended when the resulting alias is purely numeric.

Settings in Render Settings

The alias attribute has no specific render settings. In the attribute list of a render setting, the usual options are available:

Option	Description
Template	Selection of a custom template for the output of the alias value. If no template is specified, the output is as plain text.
CSS class	Optional CSS class added to the output element.

Settings in the Input Form

When the alias attribute is added to an input form (DCA setting), the following options are available:

Display

Option	Description
Backend class	CSS classes for the display of the field in the backend form (e.g. `w50` for half width, `clr` for line break, `long` for full width).
Template for backend	Selection of a custom widget template for the backend form.
Template for frontend	Selection of a custom widget template for frontend editing (only available if the “Frontend Editing” extension is installed).

Functions

Option	Description
Required field	Makes the field a required field. If “Unique values” is active in the attribute settings, this option is set automatically.
Always save	The field is saved even if its value has not changed. If “Force alias regeneration” is active, this option is also set automatically.

Overview (backend filter and search)

Option	Description
Filterable	The attribute is available in the backend as a filter criterion.
Searchable	The attribute is available in the backend as a search field.

Filter Rules

The alias attribute can be used with the following filter rules:

Filter rule	Note
Simple lookup	Filters records by an exact or partial alias value; the alias column name is used as the URL parameter by default (e.g. `?alias=my-product` or with `auto_item` as `/my-product`) — see e.g. Detail page.
Text search	Free text input in the frontend for searching within the alias field.
Levenshtein-based search	Similarity search with typo tolerance; requires the package `attribute_levenshtein`.
Loupe	Full-text index search based on an SQLite database; requires the package `filter_loupe` (from MM 2.4).

Special Functions

Insert tags in source attributes

If a source attribute contains insert tags (e.g. {{env::page}}), these are resolved before slug generation. This allows dynamic alias components to be incorporated.

Behavior when copying a record

If “Force alias regeneration” is active, an existing alias value is not transferred when duplicating a record in the backend. Instead, a new alias is automatically generated after saving (doNotCopy behavior).

Uniqueness with automatic suffix assignment

If “Unique values” is active, the slug generator checks after generation whether the alias already exists. If a duplicate is found, Contao automatically appends a numeric suffix (e.g. my-product-2, my-product-3, etc.) until a unique value is found.

Database storage

The alias is stored as varchar(255) NULL in the MetaModel table. An empty value is stored as NULL (compatible with MySQL Strict Mode).

Beautifier special characters

The character sequences [-], [zwsp], , and &ZeroWidthSpace; (conditional hyphens used in Contao for text formatting) are automatically removed before slug generation so they do not appear in the alias.