Proper implementation with DataBinding

I’m using databinding library just as view holder. I have read through the wiki page, but I couldn’t find the way with using databinding just as view holder. (I don’t want to use ButterKnife and KotlinAndroidExtensions.) So I’m trying the code below, but I wonder if it is correct.

@EpoxyModelClass(layout = R.layout.item_hoge)
abstract class HogeItemModel : EpoxyModelWithHolder<DataBindingEpoxyHolder>() {
  @EpoxyAttribute lateinit var hoge: Hoge

  override fun bind(holder: DataBindingEpoxyHolder) {
    val binding = holder.binding as? ItemHogeBinding ?: return
    val context = binding.root.context
    Picasso.with(context).load(hoge.imageUrl).fit().into(binding.image)
  }
}

class DataBindingEpoxyHolder : EpoxyHolder() {

  @CallSuper
  override fun bindView(itemView: View) {
    binding = DataBindingUtil.bind(itemView)
  }

  lateinit var binding: ViewDataBinding
}

Do you have any suggestions?

My original adapter code(without using Epoxy) is below.

open class HogeItemAdapter(var context: Context, var items: MutableList<HogeItem>)
  : RecyclerView.Adapter<BindingHolder<ItemHogeBinding>>() {

  override fun onCreateViewHolder(parent: ViewGroup,
      viewType: Int): BindingHolder<ItemHogeBinding> {
    return BindingHolder(context, parent,
        R.layout.item_hoge)
  }

  override fun onBindViewHolder(holder: BindingHolder<ItemHogeBinding>,
      position: Int) {
    val binding = holder.binding
    val item = items[holder.adapterPosition]

    Picasso.with(context)
        .load(item.imageUrl)
        .fit()
        .into(binding.image)
  }
}

class BindingHolder<out T : ViewDataBinding>(context: Context,
    parent: ViewGroup,
    @LayoutRes layoutResId: Int)
  : RecyclerView.ViewHolder(LayoutInflater.from(context).inflate(layoutResId, parent, false)) {

  val binding: T = DataBindingUtil.bind(itemView)
}

[igreenwood]

@elihart The code that you have suggested worked perfectly fine. 😄 I am sorry I didn’t explain it clearly enough. 💦

I’m using data binding library to avoid using findViewById.(just instead of ButterKnife) I was using the data tag before, but now stop using because our app code for updating the value is becoming little complicated and it is hard to debug.

The code I wrote above seems worked but it needs “unchecked cast”, so I wanted to know if you know the better solution. I have read about DataBindingEpoxyModel, but I thought you expected that it is used with the data tag. I was worried about that unexpected usage cause some problem like performance.

Thank you very much for polite response. It’s clear now. 👍

[elihart]

Did you look at https://github.com/airbnb/epoxy/wiki/Data-Binding-Support#custom-data-binding-models?

I think that can prevent you from having to make your own BindingHolder. It passes you the ViewDataBinding automatically