Kotlin: How do I call a DialogFragment from within an Adapter class?

Question

I have a MainAdapter.kt class that handles a RecyclerView. In its Holder class, I use a OnLongClickListener that calls a function deleteCategory(categoryId) to delete an entry in my Firebase database. This works perfectly:

class CategoryHolder(val customView: View, var category: Category? = null) : RecyclerView.ViewHolder(customView) {
    private val TAG = CategoryHolder::class.java.simpleName

    fun bind(category: Category) {
        with(category) {
            customView.textView_name?.text = category.name
            customView.textView_description?.text = category.description

            val categoryId = category.id

            customView.setOnClickListener {
                    // do something
            }

            customView.setOnLongClickListener(
                    {
                       deleteCategory(categoryId)
                       true
                    }
            )
        }
    }

    private fun deleteCategory(categoryId: String) {
        val database = FirebaseDatabase.getInstance()

        val myRef = database.getReference("categories").child(categoryId)
        myRef.removeValue()
        Log.d(TAG, "Category with id " + categoryId + " deleted")
    }
}

But I rather want to call a function inside a DialogFragment class instead of the deleteCategory(id) function, like this:

  // Create an instance of a DeleteCategoryDialogFragment and show it
  fun showDeleteCategoryDialog(view: View, categoryId: String) {
      val dialog = DeleteCategoryDialogFragment.newInstance(categoryId)
      dialog.show([email protected], 
      "DeleteCategoryDialog")
  }

This gives me a "Unresolved reference: @MainActivity" error. How can I solve this? Is there a way to get hold of categoryId (of type String) in my MainActivity? This would allow me to move the function showDeleteCategoryDialog to MainActivity and solve the problem.

Answer 1

You can not refer to your MainActivity like your code above. You have to cast the context of your ViewHolder as MainActivity before using it:

val activity =  itemView.context as? MainActivity
// then you can show your dialog with activity?.supportFragmentManager