Undesired model remove event triggered

[mauron85]

Description: When model is removed from subcollection also model remove event is triggered.

Expected: when model does not satisfy filter condition anymore, only subcollection remove event should be triggered

Actual: also model remove event is triggered

Following test will fail:

  describe 'updating model', ->
    it 'should not trigger remove on the model', ->
      filter = ->
         model.get('prop') == 'val'
      parent = new Collection
      child = new Collection
      model = new Model({id:1})
      parent.add(model)
      spy = sinon.spy()
      model.on 'remove',spy
      subset = new Subset(parent:parent,child:child,filter:filter)
      expect(child.length).to.equal 0
      model.set({prop: 'val'})
      expect(child.length).to.equal 1
      model.set({prop: null})
      expect(spy.called).to.be.false

How to reproduce:
http://jsfiddle.net/mauron85/8axcsvot/3/

[mauron85]

Actually, after bit thinking I realized that it's not an issue, but my wrong assumptions.

I should not listen to model remove event, without checking which collection it was removed from.

Always do the check (probably in your view), like this:

var parent = new Collection;
var child = new Collection;
var model = new Model;
var subset = new Subset({
  parent: parent,
  child: child,
  filter: //some filter here
});

model.on('remove', function(model, collection, options) {
  if (collection === child) {
    //now you can be sure model was removed from child subcollection and from parent
  }
 });

And full test:

    it 'should not trigger remove on the model', ->
      filter = ->
        model.get('prop') == 'val'
      parent = new Collection
      child = new Collection
      model = new Model({id:1})
      parent.add(model)
      model.on 'remove', (model, collection, options)->
        expect(collection).to.equal child
      subset = new Subset(parent:parent,child:child,filter:filter)
      expect(child.length).to.equal 0
      model.set({prop: 'val'})
      expect(child.length).to.equal 1
      model.set({prop: null})

I will add remark in README.md to be aware of this, to not making same mistakes.