Added persistent storage to the NotesSample application (googlesamples#8

)

NotesSample/app/build.gradle

@@ -50,6 +50,13 @@ dependencies {
     implementation "androidx.fragment:fragment-ktx:1.2.4"
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
     implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
+    implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.0-alpha03'
     implementation 'androidx.recyclerview:recyclerview:1.1.0'
     implementation 'com.google.android.material:material:1.1.0'
+
+    // Room persistence library imports
+    implementation "androidx.room:room-runtime:$room_version"
+    implementation "androidx.room:room-ktx:$room_version"
+    implementation "androidx.room:room-rxjava2:$room_version"
+    kapt "androidx.room:room-compiler:$room_version"
 }

NotesSample/app/src/main/java/com/example/glass/notessample/model/Note.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2020 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.example.glass.notessample.model
+
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+/**
+ * Model for the single note.
+ */
+@Entity(tableName = "notes")
+data class Note(
+    @ColumnInfo val title: String,
+    @ColumnInfo val content: String,
+    @ColumnInfo val daytime: String
+) {
+    @PrimaryKey(autoGenerate = true)
+    var id: Int = 0
+}

NotesSample/app/src/main/java/com/example/glass/notessample/model/NoteViewModel.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2020 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.example.glass.notessample.model
+
+import android.app.Application
+import androidx.lifecycle.AndroidViewModel
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.viewModelScope
+import com.example.glass.notessample.storage.NoteRepository
+import com.example.glass.notessample.storage.NotesDatabase
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+
+/**
+ * View model for notes. Uses {@link NoteRepository} to communicate with the persistent storage.
+ */
+class NoteViewModel(application: Application) : AndroidViewModel(application) {
+
+    private val repository: NoteRepository
+    val allNotes: LiveData<List<Note>>
+
+    init {
+        val wordsDao = NotesDatabase.getDatabase(
+            application,
+            viewModelScope
+        ).wordDao()
+        repository = NoteRepository(wordsDao)
+        allNotes = repository.allNotes()
+    }
+
+    fun insert(note: Note) = viewModelScope.launch(Dispatchers.IO) {
+        repository.insert(note)
+    }
+
+    fun delete(note: Note) = viewModelScope.launch(Dispatchers.IO) {
+        repository.delete(note)
+    }
+
+    fun find(text: String) = repository.find(text)
+}

NotesSample/app/src/main/java/com/example/glass/notessample/storage/NoteDao.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2020 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.example.glass.notessample.storage
+
+import androidx.lifecycle.LiveData
+import androidx.room.*
+import com.example.glass.notessample.model.Note
+
+/**
+ * Dao for the notes.
+ */
+@Dao
+interface NoteDao {
+
+    @Query("SELECT * from notes")
+    fun getAll(): LiveData<List<Note>>
+
+    @Insert(onConflict = OnConflictStrategy.IGNORE)
+    suspend fun insert(note: Note)
+
+    @Delete
+    suspend fun delete(note: Note)
+
+    @Query("SELECT * FROM notes WHERE content LIKE :text")
+    fun find(text: String): LiveData<List<Note>>
+}

NotesSample/app/src/main/java/com/example/glass/notessample/storage/NoteRepository.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2020 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.example.glass.notessample.storage
+
+import androidx.lifecycle.LiveData
+import com.example.glass.notessample.model.Note
+
+/**
+ * Repository to communicate between database and view model
+ */
+class NoteRepository(private val noteDao: NoteDao) {
+
+    fun allNotes() = noteDao.getAll()
+
+    suspend fun insert(note: Note) = noteDao.insert(note)
+
+    suspend fun delete(note: Note) = noteDao.delete(note)
+
+    fun find(text: String) = noteDao.find(text)
+}

NotesSample/app/src/main/java/com/example/glass/notessample/storage/NotesDatabase.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2020 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.example.glass.notessample.storage
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+import com.example.glass.notessample.model.Note
+import kotlinx.coroutines.CoroutineScope
+
+/**
+ * Room database for notes.
+ */
+@Database(entities = [Note::class], version = 1, exportSchema = false)
+public abstract class NotesDatabase : RoomDatabase() {
+
+    abstract fun wordDao(): NoteDao
+
+    companion object {
+        private const val DATABASE_NAME = "notes"
+
+        @Volatile
+        private var INSTANCE: NotesDatabase? = null
+
+        fun getDatabase(context: Context, scope: CoroutineScope): NotesDatabase {
+            val tempInstance = INSTANCE
+            if (tempInstance != null) {
+                return tempInstance
+            }
+            synchronized(this) {
+                val instance = Room.databaseBuilder(
+                    context.applicationContext,
+                    NotesDatabase::class.java,
+                    DATABASE_NAME
+                ).build()
+                INSTANCE = instance
+                return instance
+            }
+        }
+    }
+}

NotesSample/build.gradle

@@ -16,6 +16,7 @@
 
 buildscript {
     ext.kotlin_version = '1.3.41'
+    ext.room_version = '2.2.5'
     repositories {
         google()
         jcenter()