cannot shorten array or change all of it atomically

[az143]

my model contains an array of plain string values. with deep-model i cannot shorten the array, only modify existing elements or add new ones to it.

mymodel.set({"arrayname":["val1","val2"]}) will ensure that val1 and val2 are the first two values, but nothing more. it does not do anything about the other values that the array may already contain.

this is caused by objToPath() in set translating my atomic set request into two independent requests for arrayname.0 and arrayname.1.

the only workaround that i can think of at this time is to model.set({"arrayname":null}) first to destroy the array, then rebuild it with the desired elements with a second model.set().
if anybody has a better idea i'd be grateful to hear it.

regards
az

[mogarick]

Any news about this problem. I algo have to use a workaround in order to make updates un array to be noticed. Removing elements is not detected. Even making a model.clear doesn't have any effect. I need to manually set the attributes to undefined and then reset the model with the updated values in order deep model respect array elements removing.

[kilbot]

For my project, I have fixed this problem using a parse function which compares the incoming keys against the current attributes.

I wouldn't necessarily suggest adding this to the deep-model library as it adds quite a lot of unnecessary parsing. It may be enough to extend DeepModel for only the models you require.

This issue is similar to a known Backbone.Model issue, see this quote by @jashkenas

It's the expected behavior. The server sends down attributes it would like to change on the client side. Client-side model state does not get blown away.

So the current DeepModel implementation is consistent with Backbone.Model, it's just that this produces weird effects when an array has been shortened.

[rally25rs]

I just ran into this same issue.

If you have an existing model:

const model = new MyDeepModel({
  selectedThings: [1,2]
});

and you want to change what "things are selected"

model.set({
  selectedThings: [0]
});

then the result is:

{
  selectedThings: [0,2]
}

Anyone know of a reasonable workaround? I am changing a bunch of values at one by passing an object to .set() and it isn't easy to loop over every property to see if it is an array, and if it is, then modify the existing array instead of replacing it.

It feels like .set() needs some option to "replace" existing arrays instead of modify them by index.

---

Edit: Workaround

I found a usable workaround, which is to unset the values before setting them. Something like:

const model = new MyDeepModel({
  selectedThings: [1,2]
});

const changes = {
  selectedThings: [0]
};

model
  .unset(changes, {silent: true})
  .set(changes);

model.toJSON(); // { selectedThings: [0] }