SortableMixin does not work when whole array changes

[meurkens]

I have an ArrayController of models, whose property which is the sortablePropertie is computed and can change at once, because it is dependent on a single property of another model they all belongTo.

When this happens, every object gets inserted again, but the binary search algorithm does not function properly anymore, because the whole Array became unsorted.

[trek]

Can you create a a JSFiddle or JSBin that demonstrates this problem in isolation?

[meurkens]

Something like this:
http://jsbin.com/ucanam/2024/edit?html,js,output

[wagenet]

Hmm, that seems odd. @hjdivad, can you chime in here?

[hjdivad]

both SortableMixin and Em.computed.sort fall down on this case, although for slightly different reasons.

SortableMixin

When an item's sort property changes, SortableMixin checks to see if the item is still sorted by comparing it to its left and right neighbours, and if the item is not sorted, reinserts it. This check fails when the entire array is unsorted due to batch updates, as the array will then have been sorted by prior values. In the case of this jsbin the sort is arbitrary because the initial values are all NaN.

Em.computed.sort

Em.computed.sort comes a little closer, but not much. In an attempt to handle multiple property changes (from eg setProperties) Em.computed.sort batches changes. Unfortunately, the cache is not invalidated until didChange.

Fixing SortableMixin

Fixing SortableMixin is not too much code, but it does require adding some complexity.

• add a contentItemSortPropertyWillChange, decide there whether or not to remove the item, mark it
• in contentItemSortPropertyDidChange, if the item is marked, reinsert it.

Fixing Em.computed.sort

sort needs to:

• only flush one item at a time, ie batch changes to multiple properties, but not to multiple items and
• only flush on the last property didChange, not the first.

[wagenet]

@hjdivad anything actionable here?

[hjdivad]

@wagenet yeah I need to fix the two things I listed above for Em.computed.sort; thanks for the reminder

[mlb5000]

just ran into this issue in 1.6.0-beta.5. have you made any progress on this in a branch anywhere @hjdivad ?

[wagenet]

@hjdivad ping.

[jwahdatehagh]

any news on this?

or workarounds?

[mlb5000]

@jwahdatehagh I can't confirm whether it's a fluke or actually a workaround, but I tried this again today and instead of pointing to 'model' in the Ember.computed.sort call I point at a computed property. In my case that computed property happens to filter the controller's content, but I don't know if that's strictly necessary. Maybe you'll have some luck that way?

[jwahdatehagh]

thanks @mlb5000 - i just opted out of this now - using the standard sortProperties option on the model itself with a weird workaround for sorting the properties in different directions now - but everything seems to work so far.

[wagenet]

From what @hjdivad said, the core issue is around Ember.computed.sort. Merging into #9462.