Hello I have a few questions 1 what are the use cases for `r

Question

Hello I have a few questions 1 what are the use cases for `refreshOnUpdate` I read the documentation and saw only `override fun buildClassSet classSetBuilder ClassSetBuilder `use case For example сan it interact with rendering not working ```class Example ids List lt Long gt SimplePanel var myIds by refreshOnUpdate ids init button $ myIds interact somehow onClickLaunch myIds = listOf 2L ``` 2 What if I have a component where models comes as an argument `models ObservableValue lt List lt Order gt gt ` Inside I create `val pagination ObservableValue lt Pagination gt ` Next I want to have a `div` that will change when the `models` changes or when the `pagination` changes I can t figure out how to achieve this now For example I can t put models and pagination in `val state ObservableValue lt SomeState gt ` because `models` are being updated in another component but the rerender will only happen when the `state` changes `state setValue state value apply `

Robert Jaros · Answer

`refreshOnUpdate` delegate lets you easily declare properties which change how the component should be rendered what element is rendered and what attributes classes and styles are applied to it When used it will re render the component when the value is set In general you don t need to use refreshOnUpdate unless you are implementing some kind of advanced component

Robert Jaros · Answer

In your example there is no point using refreshOnUpdate because your component doesn t change when `myIds` variable changes It s child component does but the init block is not called on re rendering

Robert Jaros · Answer

You should rather use this code to explicitly modify child component ```class Example ids List lt Long gt SimplePanel var myIds = ids set value field = value button text = $value private val button Button init button = button $ids interact somehow onClick myIds = listOf 2L ```

Ilya Tel · Answer

Oh well I think I get it what about the second question At the moment I m a little confused because I don t know how to bind a component to several different `ObservableValue`

Robert Jaros · Answer

Use `RefreshOnUpdate` when you are overrding methods like `render` `buildClassSet` `buildAttributesSet` `childrenVNodes`

Robert Jaros · Answer

As for the second question you can t

Robert Jaros · Answer

You should join these observables into a single one

Ilya Tel · Answer

ok thanks for the help

Robert Jaros · Answer

You don t need to use only a single one observable for everything like some kind of strict single source of truth principle But you should divide your state into rather independent parts

Robert Jaros · Answer

If you want to be sure some components won t be unnecessarily refreshed you can bind to a part of your state using `bind` with a `sub` parameter

Robert Jaros · Answer

It will create an internal sub observable that will change only when selected part of the main state changes

Ilya Tel · Answer

As far as I understand in KVision it is not very convenient to update a multi level store and a multi level store is not what should be used in KVision

Robert Jaros · Answer

You mean observables inside other observables

Ilya Tel · Answer

No I mean one single ObservableValue that would serve as a tiered storage What about observables inside other observables doesn t that look pointless

Robert Jaros · Answer

Yes observables inside observables are bad slightly smiling face

Robert Jaros · Answer

The state should be immutable

Robert Jaros · Answer

If you want more convenient method to work with more complex state you can try using copykat <https github com kopykat kt kopykat> Haven t tried this myself but it looks nice