Filter-by-related

The “Filter-by-related” filter rule (package filter_by_related, from MM 2.4) allows items to be filtered based on properties of a related (relational) MetaModel. The relation between the main MetaModel and the related MetaModel can be built either via a child table (pid relation) or via a single-select attribute (select relation).

For example, in a “Manufacturer → Products” structure, items can be filtered by properties of the manufacturer (e.g. “Show all products from manufacturers in Germany”).

Optionally, a frontend widget can be rendered that allows visitors to select a value themselves.

With the “Static parameter” option, a pre-selectable value can be set in the MetaModels list and filter CE/FE module as an overridable filter setting — see Restricting Items in CE/FE Module MM List and MM Filter.

See also

Detailed documentation on Filter-by-related: Filter-by-related for MetaModels

Installation

The filter rule is installed via the Contao Manager or Composer:

composer require metamodels/filter_by_related

Settings when Creating the Filter Rule

Setting	Description
Type	Selection of the filter rule type — here: “Filter-by-related”.
Enabled	Enables or disables this filter rule.
Comment	Free text field for describing the purpose of this filter rule.
Related MetaModel	The MetaModel through which the relation is built (the “parent MetaModel”).
Relation column	Defines how the relation to the main MetaModel is built: PID — Via the child table relation (pid field) Meta attribute — Via a meta attribute Attribute — Via a single-select attribute in the main MetaModel
Related attribute	The attribute in the related MetaModel by whose value items are filtered.
Label attribute	The attribute in the related MetaModel whose value is used as display text in the frontend widget.

Settings for the Frontend Widget

Setting	Description
URL parameter	The key of the URL parameter for passing the filter value. Without input, the column name of the attribute is used. With auto_item, only the value — without key — is embedded in the URL.
URL type for the parameter	Defines whether the parameter is passed as a slug (friendly URL) or as a GET parameter (from MM 2.4) — see SEO
Static parameter	If this option is active, the filter value can be pre-set with an overridable selection from a dropdown in the content element/module.
Provide frontend widget	Renders a filter widget in the frontend.
Widget type	Display type of the frontend widget: Select — Dropdown list (default) Text — Text input field Radio — Radio buttons Checkbox — Checkboxes
Allow empty value	If this option is active and the URL parameter is empty, no filter is applied.
Label	Label of the filter widget.
Hide label at filter widget	Suppresses the output of the label.
Template	Template for the widget output.
Default	Pre-selected value in the frontend widget.
Allow empty selection	Adds an empty option (“All”).
Only assigned values	Shows only values that actually exist in a relation.
Only remaining values	Shows only values for which results still exist after applying other filters.
Ignore this filter for remaining values	This filter does not return its own options as a restriction when calculating remaining values.

Matching Attributes

The “Filter-by-related” filter rule does not work with an attribute of the main MetaModel, but with attributes of the related MetaModel. Any attribute types can be filtered there.

The relation to the main MetaModel can be built via the following attribute types:

• Single select [select]

• Child table relation (pid/ptable)