dataconnect: demo: add "Delete" button an "List Items" screen.

firebase-dataconnect/demo/firebase/dataconnect/connector/operations.gql

@@ -49,6 +49,26 @@ query GetItemByKey(
   }
 }
 
+query GetAllItems @auth(level: PUBLIC) {
+  items: zwda6x9zyys {
+    id
+    string
+    int
+    int64
+    float
+    boolean
+    date
+    timestamp
+    any
+  }
+}
+
+mutation DeleteItemByKey(
+  $key: zwda6x9zyy_Key!
+) @auth(level: PUBLIC) {
+  zwda6x9zyy_delete(key: $key)
+}
+
 # This mutation exists only as a workaround for b/382688278 where the following
 # compiler error will otherwise result when compiling the generated code:
 #   Serializer has not been found for type 'java.util.UUID'. To use context

firebase-dataconnect/demo/src/main/AndroidManifest.xml

@@ -16,13 +16,12 @@ See the License for the specific language governing permissions and
 limitations under the License.
 -->
 
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools">
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
     <application
         android:name=".MyApplication"
         android:label="Data Connect Minimal Demo"
-        android:theme="@style/Theme.AppCompat.NoActionBar"
+        android:theme="@style/Theme.AppCompat"
         >
 
         <activity android:name=".MainActivity" android:exported="true">
@@ -32,6 +31,11 @@ limitations under the License.
             </intent-filter>
         </activity>
 
+        <activity
+            android:name=".ListItemsActivity"
+            android:label="List Items"
+            />
+
     </application>
 
 </manifest>

firebase-dataconnect/demo/src/main/kotlin/com/google/firebase/dataconnect/minimaldemo/ListItemsActivity.kt

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.firebase.dataconnect.minimaldemo
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.activity.viewModels
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.flowWithLifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.recyclerview.widget.DividerItemDecoration
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import com.google.firebase.dataconnect.minimaldemo.connector.GetAllItemsQuery
+import com.google.firebase.dataconnect.minimaldemo.databinding.ActivityListItemsBinding
+import com.google.firebase.dataconnect.minimaldemo.databinding.ListItemBinding
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.launch
+
+class ListItemsActivity : AppCompatActivity() {
+
+  private lateinit var myApplication: MyApplication
+  private lateinit var viewBinding: ActivityListItemsBinding
+  private val viewModel: ListItemsViewModel by viewModels { ListItemsViewModel.Factory }
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    myApplication = application as MyApplication
+
+    viewBinding = ActivityListItemsBinding.inflate(layoutInflater)
+    viewBinding.recyclerView.also {
+      val linearLayoutManager = LinearLayoutManager(this)
+      it.layoutManager = linearLayoutManager
+      val dividerItemDecoration = DividerItemDecoration(this, linearLayoutManager.layoutDirection)
+      it.addItemDecoration(dividerItemDecoration)
+    }
+    setContentView(viewBinding.root)
+
+    lifecycleScope.launch {
+      if (viewModel.loadingState == ListItemsViewModel.LoadingState.NotStarted) {
+        viewModel.getItems()
+      }
+      viewModel.stateSequenceNumber.flowWithLifecycle(lifecycle).collectLatest {
+        onViewModelStateChange()
+      }
+    }
+  }
+
+  private fun onViewModelStateChange() {
+    val items = viewModel.result?.getOrNull()
+    val exception = viewModel.result?.exceptionOrNull()
+    val loadingState = viewModel.loadingState
+
+    if (loadingState == ListItemsViewModel.LoadingState.InProgress) {
+      viewBinding.statusText.text = "Loading Items..."
+      viewBinding.statusText.visibility = View.VISIBLE
+      viewBinding.recyclerView.visibility = View.GONE
+      viewBinding.recyclerView.adapter = null
+    } else if (items !== null) {
+      viewBinding.statusText.text = null
+      viewBinding.statusText.visibility = View.GONE
+      viewBinding.recyclerView.visibility = View.VISIBLE
+      val oldAdapter = viewBinding.recyclerView.adapter as? RecyclerViewAdapterImpl
+      if (oldAdapter === null || oldAdapter.items !== items) {
+        viewBinding.recyclerView.adapter = RecyclerViewAdapterImpl(items)
+      }
+    } else if (exception !== null) {
+      viewBinding.statusText.text = "Loading items FAILED: $exception"
+      viewBinding.statusText.visibility = View.VISIBLE
+      viewBinding.recyclerView.visibility = View.GONE
+      viewBinding.recyclerView.adapter = null
+    } else {
+      viewBinding.statusText.text = null
+      viewBinding.statusText.visibility = View.GONE
+      viewBinding.recyclerView.visibility = View.GONE
+    }
+  }
+
+  private class RecyclerViewAdapterImpl(val items: List<GetAllItemsQuery.Data.ItemsItem>) :
+    RecyclerView.Adapter<RecyclerViewViewHolderImpl>() {
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerViewViewHolderImpl {
+      val binding = ListItemBinding.inflate(LayoutInflater.from(parent.context), parent, false)
+      return RecyclerViewViewHolderImpl(binding)
+    }
+
+    override fun getItemCount() = items.size
+
+    override fun onBindViewHolder(holder: RecyclerViewViewHolderImpl, position: Int) {
+      holder.bindTo(items[position])
+    }
+  }
+
+  private class RecyclerViewViewHolderImpl(private val binding: ListItemBinding) :
+    RecyclerView.ViewHolder(binding.root) {
+
+    fun bindTo(item: GetAllItemsQuery.Data.ItemsItem) {
+      binding.id.text = item.id.toString()
+      binding.name.text = item.string
+    }
+  }
+}

firebase-dataconnect/demo/src/main/kotlin/com/google/firebase/dataconnect/minimaldemo/ListItemsViewModel.kt

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.firebase.dataconnect.minimaldemo
+
+import android.util.Log
+import androidx.annotation.MainThread
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.ViewModelProvider.AndroidViewModelFactory.Companion.APPLICATION_KEY
+import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import com.google.firebase.dataconnect.minimaldemo.connector.GetAllItemsQuery
+import com.google.firebase.dataconnect.minimaldemo.connector.execute
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.Deferred
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.async
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.launch
+
+class ListItemsViewModel(private val app: MyApplication) : ViewModel() {
+
+  // Threading Note: _state and the variables below it may ONLY be accessed (read from and/or
+  // written to) by the main thread; otherwise a race condition and undefined behavior will result.
+  private val _stateSequenceNumber = MutableStateFlow(111999L)
+  val stateSequenceNumber: StateFlow<Long> = _stateSequenceNumber.asStateFlow()
+
+  var result: Result<List<GetAllItemsQuery.Data.ItemsItem>>? = null
+    private set
+
+  private var job: Job? = null
+  val loadingState: LoadingState =
+    job.let {
+      if (it === null) {
+        LoadingState.NotStarted
+      } else if (it.isCancelled || it.isCompleted) {
+        LoadingState.Completed
+      } else {
+        LoadingState.InProgress
+      }
+    }
+
+  enum class LoadingState {
+    NotStarted,
+    InProgress,
+    Completed,
+  }
+
+  @OptIn(ExperimentalCoroutinesApi::class)
+  @MainThread
+  fun getItems() {
+    // If there is already a "get items" operation in progress, then just return and let the
+    // in-progress operation finish.
+    if (loadingState == LoadingState.InProgress) {
+      return
+    }
+
+    // Start a new coroutine to perform the "get items" operation.
+    val job: Deferred<List<GetAllItemsQuery.Data.ItemsItem>> =
+      viewModelScope.async { app.getConnector().getAllItems.execute().data.items }
+
+    this.result = null
+    this.job = job
+    _stateSequenceNumber.value++
+
+    // Update the internal state once the "get items" operation has completed.
+    job.invokeOnCompletion { exception ->
+      // Don't log CancellationException, as documented by invokeOnCompletion().
+      if (exception is CancellationException) {
+        return@invokeOnCompletion
+      }
+
+      val result =
+        if (exception !== null) {
+          Log.w(TAG, "WARNING: Getting all items FAILED: $exception", exception)
+          Result.failure(exception)
+        } else {
+          val items = job.getCompleted()
+          Log.i(TAG, "Retrieved all items ${items.size} items")
+          Result.success(items)
+        }
+
+      viewModelScope.launch {
+        if ([email protected] === job) {
+          [email protected] = result
+          [email protected] = null
+          _stateSequenceNumber.value++
+        }
+      }
+    }
+  }
+
+  companion object {
+    private const val TAG = "ListItemsViewModel"
+
+    val Factory: ViewModelProvider.Factory = viewModelFactory {
+      initializer { ListItemsViewModel(this[APPLICATION_KEY] as MyApplication) }
+    }
+  }
+}