stateManager.getCollection - review / generalize options

[b-ma]

options could be:

Generalize existing parameter filtering feature (apply to SharedState and SharedCollection):

• whitelist - same behaviour as current filter argument
• blacklist - inverse of whitelist

Allow to model some hierarchies / relationships (apply to SharedCollection):

• contraint - arbitrary function to filter the states that live in the collection, could be useful e.g. to model sort of simple "join"

const parent = stateManager.attach('parent');
const children = stateManager.getCollection('child', {
   constraint: values => values.parentId === parent.id
});

This could be quite simply done on the client side, just detaching early from the state if the value does not match, or even by propagating init state values in OBSERVE_NOTIFICATION to avoid additional network roundtrips.

The constraint could also be a pure facade, allowing to insert / remove a state from the collection when one of it's param changes and match the constrain... to be discussed

Maybe provide both behaviours:

• staticContraint - check is done only on init values when the state is created (better in terms of network load)
• liveContraint - The state is attached but added / removed from collection dynamically at any moment

Would also benefit from #93

[jipodine]

Why not keep the whitelist (and maybe blacklist) for the subscriptions? constraint sounds more like a requirement to me. (If constraint' is to be used, do not forget thes`.)

• dynamicWhitelist
• staticWhitelist

Is there a way to integrate that with the filtering of attributes, to get only a subset (regardless of their values)?

[b-ma]

filter rather than constraint

[b-ma]

Actually the dynamicFilter behavior is not very relevant as we already have the SharedStateCollection#filter method. This would also create problems such as how to be notified when the collection change, etc.

For now, let's just stick with something like:

stateManager.getCollection('test', {
  whitelistParams: ['a', 'b'],
  backlistParams: ['a', 'b'],
  filterStates: (currentValues) => currentValues.group === 'group-1',
});