New parameter type: entity_class

[jkiviluo]

Parameter value can be chosen from the entities of a particular entity_class.

It could be UNIQUE (only one entity can be chosen for an entity - hard to enforce due to alternatives --> should be checked that uniqueness is not violated for any scenario) or ONE-TO-MANY.

Implementation idea: Use actual nD entity_classes to store the information (just don't show the entity_class in the tree - unless specifically chosen to do so). This way we can keep referential integrity.

[soininen]

How would the uniqueness work if more than one parameter was of entity_class type in an entity? What if you built an array or a map of entity_class?

[jkiviluo]

How would the uniqueness work if more than one parameter was of entity_class type in an entity? Good question.

• Let's say we have entity classes fish and species
• Then user creates an 'entity_class parameter' species for the fish class
• This should create a new entity_class fish__species (with entity_activity False by default)
• Then user adds a species parameter for the fish Fred. Fred is to be of species perch.
• New entity Fred__perch is made and it's entity_active is set to True in the alternative user has chosen
• To enforce uniqueness, we would need to make a check for each scenario that Fred does not have more than one fish__species members. Cumbersome, but possible (unless it can be made with SQL itself).

Maybe we can see how this works without the UNIQUE constraint first.