Association Properties
Introduction
There are two ways to edit the properties of an association. This page describes the properties you can edit in the properties pane of the association in the domain model, or from opening the association properties dialog directly from the association or the association tab in the entity properties.
You can also edit an association directly within the association tab in the entity properties. For more information see Association Tab Properties.
Association Properties
An example of the association properties is represented in the image below:
Associations have the following properties:
Name
The name used to refer to the association. For example, in forms or microflows.
Export Level
Export level allows you to define access level to this document on the consumer (customer) side when developing an add-on module or a solution.
| Value | Description |
|---|---|
| Hidden (default) | The document/element content is hidden from a consumer. |
| Usable | Consumers can see the association in the domain model and use it in their app. |
Documentation
You can write notes and documentation in the Documentation property.
Multiplicity
Multiplicity can be of the following types:
| Multiplicity | Meaning | Equivalent of |
|---|---|---|
| One-to-one | One X object is associated with one Y object | An association of type Reference with owner set to Both |
| One-to-many (default) | One X object is associated with multiple Y object | An association of type Reference with owner set to Default |
| Many-to-many | Multiple X objects are associated with multiple Y objects | An association of type Reference set – in this case ownership is set by the Navigability property |
For more information about association types, see the Type section in Association Tab Properties, and for information on ownership, see the Owner section in Association Tab Properties.
Navigability
| Navigability | Meaning | Equivalent of |
|---|---|---|
| X objects refer to Y objects (default) | The owner of the association is X | An association of type Reference set with owner set to Default |
| X and Y objects refer to each other | Both entities are owners | An association of type Reference set with owner set to Both |
This corresponds to the Owner property for Reference sets. See the Owner section of Association Tab Properties for a more detailed discussion of the impact of changing navigability.
Despite its name, navigability is usually only important when adding or changing associations. Making one object owner of an association does not prevent you reading the association from the non-owner end.
One-Way Navigable Associations
One-way navigable associations are associations that allow navigation to associated entities only in a single direction: from parent to child. These associations are typically introduced by OData service integration, either through an external provider or the Mendix Data Hub, in external entities. The major implications of one-way navigability are related to XPath use cases such as constraints and queries.
You can retrieve data from all other domain model associations in both directions.
One-way navigable associations are represented by a dashed arrow in Domain model editor. An icon shows the direction of its navigability.
Delete Behavior
| Value | Description |
|---|---|
| Delete {name of entity} object but keep {name of other entity} object(s) (default) | When an object is deleted, the associated object(s) are not deleted. |
| Delete {name of entity} object and {name of other entity} object(s) as well[1] | When an object is deleted, the associated object(s) are also deleted. |
| Delete {name of entity} object only if it is not associated with {name of other entity}[2] object(s) | An object can only be deleted if it is not associated with any other object(s). |
[1] This delete behavior is used if you want to delete any associated Profile when a Customer is deleted:
[2] This delete behavior is used if you want to be able to delete a Customer only if it is not associated with any Order. In this case you will be asked to enter an Error message if ‘Customer’ object cannot be deleted to inform the end user that this customer cannot be deleted and perhaps suggest a next course of action:
