Add “Association table with user data” as an additional Association option

3

With Direct Associations Mendix has taken a big step in simplifying the data model and improving performance. One gap that still hurts in real apps: associations that need their own user data.

For example when you create a Project tracking app to keep an overview of which employee works on which projects, you would have the following entities:

• Project

• Employee

Considering an Employee can work 40% on Project A and 60% on Project B

• We need AllocationPercentage on the relationship

Today this always means:

• Create a join entity (e.g. ProjectEmployee)

• Add Project, Employee, AllocationPercentage

• Add 2 associations (Project to ProjectEmployee and Employee to ProjectEmployee)

• Build custom pages and microflows to maintain this from both sides

• Lose the simplicity and widget support we have with “normal” associations (e.g.  Combobox)

 

Proposal

Extend the association model with a third option (next to usual Association and Direct Association):

• Association table with user data

The “Association table with user data” would:

• Be defined in the association editor between two entities, like a regular association would

• Let the modeller add attributes on the association itself (AllocationPercentage, ValidFrom, Role, etc.)

• Be physically backed by a join table/entity that Mendix creates and manages (storage, indexes, migration)

• Be understood by association-aware widgets (Combobox, reference selectors, datagrids), so you can:

  • Select related objects as with a normal association

  • Edit the extra association attributes inline (e.g. AllocationPercentage)

So from a modeller’s point of view it behaves like “an association with extra fields”, without having to manually design and wire up a separate entity and custom maintenance screens.

Benefits

• Keeps the solution low-code and close to how business thinks: “Project–Employee with an allocation”, not “extra technical entity”.

• Reuses existing association widgets and patterns instead of custom maintenance UIs.

• Reduces boilerplate for very common patterns (Project–Employee, Student–Course with Grade, User–Role with ValidFrom/ValidUntil, etc.).

In short: making “Association table with user data” a first-class association option next to Direct association and Association table would close a real gap in the platform, especially for many-to-many relations that need just a bit more information than a simple link.

asked 2025-12-10

1 answers