Limiting the relations accepted for computation of HierarchyWithin / HierarchyWithinRoot / FacetSummary / HierarchyStatistics

[novoj]

The HierarchyWithin only uses a filter constraint that selects the considered node for the hierarchy lookup, the same is true for FacetSummary and HierarchyStatistics.

However, there might be a use case where the client wants to consider only those relations to the target entities that match a certain constraint.

Let's look at this picture:

What if we want to consider only relations with attribute disabled="false" and want to list all products in category (hierarchy node) two?! Currently, product 1 would be returned even if we use the additional constraint referenceHaving(attributeEqualsFalse("disabled")) because it has another relation to another node with attribute disabled set to true.

Therefore, we need a new way to specify which relations should be considered when evaluating relation constraints. We came up with the following idea:

In filter section:

hierarchyWithin(
    attributeEquals("code", "ABC"),
    considerReferencesHaving(
    	attributeEqualsFalse("disabled")
    )
    excluding(
	attributeEquals("code", "DEF")
    )
)

In requirements:

facetSummary(
    filterBy(
       inRange("validity", now())
    )
    filterGroupBy(
       attributeEqualsTrue("filterable")
    )
    considerReferencesHaving(
    	attributeEqualsFalse("disabled")
    )
)

We first thought about reusing the referenceHaving constraint, but it also allows an entityHaving sub-constraint, which doesn't make sense in this situation. Therefore, we think we need a differently named constraint container that would accept filtering constraints that target only attributes of the reference and nothing else.