Question: What is the best method for retrieving supported properties from memberAssertion?

[johnslaughter-ihsmarkit]

So, this might tie into my earlier question about apiDocumentation (https://github.com/hypermedia-app/Alcaeus/issues/259). I'm currently attempting to map from memberAssertion to supported properties. How is this expected to be done in Alcaeus?

[tpluscode]

If I understood correctly, you'd want to do smth like finding the supported properties of types used in member assertion?

Here's an example using Alcaeus' object model

const client = require("[email protected]/node").Hydra
const { rdf } = require('@tpluscode/rdf-ns-builders')

const { representation: { root: collection } } = await client.loadResource('https://always-read-the-plaque.herokuapp.com/plaques');
const apiDoc = client.apiDocumentations[0].root

// find hydra:object of member assertions for rdf:type
const types = collection.memberAssertion
  .filter(ma => ma.property.equals(rdf.type))
  .map(ma => ma.object)

// create a map of [type URI, properties]
types.map(type => {
  const typeResource = apiDoc.supportedClass.find(sc => sc.equals(type))    
  return [type.id, typeResource ? typeResource.supportedProperty : []]
})

This returns empty in the example because of subclassing. The supported class is a subclass of the type from member assertion

RunKit: https://runkit.com/embed/k03op2du1o4h

---

Alternatively you can use clownface. IT is a good way to traverse the graphs that way

const client = require("[email protected]/node").Hydra
const { rdf, hydra } = require('@tpluscode/rdf-ns-builders')

const { representation: { root: collection } } = await client.loadResource('https://always-read-the-plaque.herokuapp.com/plaques');
const apiDoc = client.apiDocumentations[0].root

let types = collection.pointer
  .out(hydra.memberAssertion)
  .has(hydra.property, rdf.type)
  .out(hydra.object)
  .terms

types.map(type => {
  return [type, apiDoc.pointer
    .node(type)
    .out(hydra.supportedProperty)
    .toArray()]
})

RunKit: https://runkit.com/embed/275daycyc1iz

Does this help? Could you explain some more, what is the usage scenario and desired outcome?