What do you think to what extent is it permissible to load d

Question

What do you think to what extent is it permissible to load dataBinding with logic for example if I need to process a click on a button should I create a separate interface for this event or is it permissible to directly call viewModel methods to handle this event for example if all the presentation logic is one single click would it not be unnecessary to create a separate interface for this

gildor · Answer

why do you need interface for this at all Just use binding to call m ethod of your model

Loboda Deni · Answer

I was told that it is worth protecting the view from logic as much as possible and that it is not correct to call methods for example viewModel from xml

Loboda Deni · Answer

all the same in this case we get a rigid binding to a specific viewModel and reusing this xml will be problematic

gildor · Answer

but it s just a method in interface if you have multiple VMs which implement the same interface

Loboda Deni · Answer

that is it turns out all the same separate interfaces are needed

gildor · Answer

still not sure what you mean

gildor · Answer

if you want to reuse one binding layout for multiple view models you have 2 choices pass 1 view model interface as `model` variable and bind it so every view model have to implement it pass multiple variables to layout and bind each of them so it s not necessary to implement any particular interface But option 1 looks better for me and this what we use mostly

Loboda Deni · Answer

look for example I have a viewHolder I can specify viewModel as the click event handler but then this xml cannot be reused but I can create a separate interface but then we get an extra class in the project structure and which approach is better I haven t understand

Loboda Deni · Answer

I just don t want to clog the project with interfaces in which there is only one method for example click processing

gildor · Answer

Do you really have many view holders with only onclick method and no other things to bind

gildor · Answer

like actual data of item

gildor · Answer

Usually we have view model for list item and layout for list item

Loboda Deni · Answer

not I have data as a separate object event processing as a separate one but yes it is often found that for one holder only one event is somehow

Loboda Deni · Answer

sorry for the tautology

gildor · Answer

if you think it works better for you okay but we usually just have all listeners on view model it makes bind code a lot easier

gildor · Answer

but in this case I still don t see any issue pass your event listener interface as separate variable

gildor · Answer

it can be one interface for all cases

Loboda Deni · Answer

My question was should there be a viewHolder event logic in a separate interface or can it be combined with viewModel

gildor · Answer

I personally combine with viewModel probably always

Loboda Deni · Answer

understood thanks

gildor · Answer

Also on our project we now discourage using pure data classes for models because it too restrictive and not flexible you very often want to have additional logic now on in future and usage of data class doesn t allow change logic of view model and would require refactoring even if very small behavior change is needed So we always wrap it to view model class