Update StartFragment to use view model

app/src/main/java/com/example/cupcake/StartFragment.kt

@@ -15,12 +15,14 @@
  */
 package com.example.cupcake
 
+import OrderViewModel
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.widget.Toast
 import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.findNavController
 import com.example.cupcake.databinding.FragmentStartBinding
 
@@ -33,6 +35,7 @@ class StartFragment : Fragment() {
     // This property is non-null between the onCreateView() and onDestroyView() lifecycle callbacks,
     // when the view hierarchy is attached to the fragment.
     private var binding: FragmentStartBinding? = null
+    private val sharedViewModel: OrderViewModel by activityViewModels()
 
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
@@ -58,9 +61,14 @@ class StartFragment : Fragment() {
      * Start an order with the desired quantity of cupcakes and navigate to the next screen.
      */
     fun orderCupcake(quantity: Int) {
+        sharedViewModel.setQuantity(quantity)
+        if (sharedViewModel.hasNoFlavorSet()) {
+            sharedViewModel.setFlavor(getString(R.string.vanilla))
+        }
         findNavController().navigate(R.id.action_startFragment_to_flavorFragment)
     }
 
+
     /**
      * This fragment lifecycle method is called when the view hierarchy associated with the fragment
      * is being removed. As a result, clear out the binding object.

app/src/main/java/com/example/cupcake/model/OrderViewModel.kt

@@ -26,4 +26,8 @@ class OrderViewModel : ViewModel() {
     fun setDate(pickupDate: String) {
         _date.value = pickupDate
     }
+
+    fun hasNoFlavorSet(): Boolean {
+        return _flavor.value.isNullOrEmpty()
+    }
 }
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