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Add a Guestbook example for the standard environment that uses the Cloud
Datastore Java API.
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‎appengine/guestbook-cloud-datastore/README.md

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# appengine/guestbook-cloud-datastore
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An App Engine guestbook using Java, Maven, and the Cloud Datastore API via
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[google-cloud-java](https://github.com/GoogleCloudPlatform/google-cloud-java).
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Please ask questions on [StackOverflow](http://stackoverflow.com/questions/tagged/google-app-engine).
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## Running Locally
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First, pick a project ID. You can create a project in the [Cloud Console] if you'd like, though this
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isn't necessary unless you'd like to deploy the sample.
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Second, modify `Persistence.java`: replace `your-project-id-here` with the project ID you picked.
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Then start the [Cloud Datastore Emulator](https://cloud.google.com/datastore/docs/tools/datastore-emulator):
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gcloud beta emulators datastore start --project=YOUR_PROJECT_ID_HERE
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Finally, in a new shell, [set the Datastore Emulator environmental variables](https://cloud.google.com/datastore/docs/tools/datastore-emulator#setting_environment_variables)
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and run
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mvn clean appengine:devserver
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## Deploying
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Modify `appengine-web.xml` to reflect your app ID and version, then:
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mvn clean appengine:update

‎appengine/guestbook-cloud-datastore/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<packaging>war</packaging>
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<version>1.0-SNAPSHOT</version>
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<groupId>com.example.appengine</groupId>
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<artifactId>appengine-guestbook-cloud-datastore</artifactId>
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<properties>
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<guava.version>19.0</guava.version>
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</properties>
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<parent>
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<groupId>com.google.cloud</groupId>
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<artifactId>doc-samples</artifactId>
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<version>1.0.0</version>
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<relativePath>../..</relativePath>
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</parent>
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<!-- [START set_versions] -->
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<prerequisites>
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<maven>3.3.9</maven>
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</prerequisites>
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<!-- [END set_versions] -->
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<dependencies>
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<!-- Compile/runtime dependencies -->
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-api-1.0-sdk</artifactId>
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<version>${appengine.sdk.version}</version>
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</dependency>
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<dependency>
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<groupId>javax.servlet</groupId>
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<artifactId>servlet-api</artifactId>
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<version>2.5</version>
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<scope>provided</scope>
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</dependency>
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<dependency>
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<groupId>jstl</groupId>
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<artifactId>jstl</artifactId>
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<version>1.2</version>
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</dependency>
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<dependency>
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<groupId>com.google.cloud</groupId>
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<artifactId>google-cloud</artifactId>
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<version>0.4.0</version>
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</dependency>
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<dependency>
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<groupId>com.google.guava</groupId>
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<artifactId>guava</artifactId>
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<version>${guava.version}</version>
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</dependency>
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<!-- Test Dependencies -->
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.12</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>org.mockito</groupId>
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<artifactId>mockito-all</artifactId>
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<version>1.10.19</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-testing</artifactId>
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<version>${appengine.sdk.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-api-stubs</artifactId>
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<version>${appengine.sdk.version}</version>
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<scope>test</scope>
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</dependency>
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<dependency>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-tools-sdk</artifactId>
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<version>${appengine.sdk.version}</version>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<build>
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<!-- for hot reload of the web application-->
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<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
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<plugins>
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<plugin>
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<groupId>com.google.appengine</groupId>
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<artifactId>appengine-maven-plugin</artifactId>
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<version>${appengine.sdk.version}</version>
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<configuration>
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<enableJarClasses>false</enableJarClasses>
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<!-- Comment in the below snippet to bind to all IPs instead of just localhost -->
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<!-- address>0.0.0.0</address>
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<port>8080</port -->
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<!-- Comment in the below snippet to enable local debugging with a remote debugger
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like those included with Eclipse or IntelliJ -->
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<!-- jvmFlags>
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<jvmFlag>-agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n</jvmFlag>
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</jvmFlags -->
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</configuration>
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</plugin>
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</plugins>
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</build>
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</project>

‎appengine/guestbook-cloud-datastore/src/main/java/com/example/guestbook/Greeting.java

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/**
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* Copyright 2016 Google Inc. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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//[START all]
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package com.example.guestbook;
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import static com.example.guestbook.Persistence.getDatastore;
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import com.google.cloud.datastore.DateTime;
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import com.google.cloud.datastore.Entity;
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import com.google.cloud.datastore.FullEntity;
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import com.google.cloud.datastore.FullEntity.Builder;
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import com.google.cloud.datastore.IncompleteKey;
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import com.google.cloud.datastore.Key;
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import java.util.Date;
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import java.util.Objects;
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public class Greeting {
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private Guestbook book;
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public Key key;
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public String authorEmail;
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public String authorId;
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public String content;
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public Date date;
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public Greeting() {
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date = new Date();
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}
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public Greeting(String book, String content) {
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this();
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this.book = new Guestbook(book);
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this.content = content;
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}
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public Greeting(String book, String content, String id, String email) {
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this(book, content);
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authorEmail = email;
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authorId = id;
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}
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/**
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* Load greeting from Datastore entity
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*
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* @param entity
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*/
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public Greeting(Entity entity) {
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key = entity.hasKey() ? entity.key() : null;
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authorEmail = entity.contains("authorEmail") ? entity.getString("authorEmail") : null;
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authorId = entity.contains("authorId") ? entity.getString("authorId") : null;
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date = entity.contains("date") ? entity.getDateTime("date").toDate() : null;
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content = entity.contains("content") ? entity.getString("content") : null;
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}
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public void save() {
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if (key == null) {
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key = getDatastore().allocateId(makeIncompleteKey()); // Give this greeting a unique ID
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}
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Builder<Key> builder = FullEntity.builder(key);
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if (authorEmail != null) {
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builder.set("authorEmail", authorEmail);
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}
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if (authorId != null) {
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builder.set("authorId", authorId);
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}
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builder.set("content", content);
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builder.set("date", DateTime.copyFrom(date));
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getDatastore().put(builder.build());
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}
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private IncompleteKey makeIncompleteKey() {
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// The book is our ancestor key.
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return Key.builder(book.getKey(), "Greeting").build();
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}
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@Override
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public boolean equals(Object o) {
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if (this == o) {
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return true;
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}
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if (o == null || getClass() != o.getClass()) {
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return false;
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}
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Greeting greeting = (Greeting) o;
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return Objects.equals(key, greeting.key) &&
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Objects.equals(authorEmail, greeting.authorEmail) &&
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Objects.equals(authorId, greeting.authorId) &&
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Objects.equals(content, greeting.content) &&
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Objects.equals(date, greeting.date);
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}
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@Override
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public int hashCode() {
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return Objects.hash(key, authorEmail, authorId, content, date);
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}
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}
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//[END all]

‎appengine/guestbook-cloud-datastore/src/main/java/com/example/guestbook/Guestbook.java

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/**
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* Copyright 2016 Google Inc. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.guestbook;
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import static com.example.guestbook.Persistence.getDatastore;
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import static com.example.guestbook.Persistence.getKeyFactory;
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import static com.google.cloud.datastore.StructuredQuery.OrderBy.desc;
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import static com.google.cloud.datastore.StructuredQuery.PropertyFilter.hasAncestor;
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import com.google.cloud.datastore.Entity;
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import com.google.cloud.datastore.EntityQuery;
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import com.google.cloud.datastore.Key;
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import com.google.cloud.datastore.KeyFactory;
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import com.google.cloud.datastore.Query;
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import com.google.cloud.datastore.QueryResults;
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import com.google.common.collect.ImmutableList;
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import com.google.common.collect.ImmutableList.Builder;
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import java.util.List;
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//[START all]
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public class Guestbook {
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private static final KeyFactory kf = getKeyFactory(Guestbook.class);
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private final Key key;
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public final String book;
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public Guestbook(String book) {
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this.book = book == null ? "default" : book;
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key = kf.newKey(this.book); // There is a 1:1 mapping between Guestbook names and Guestbook objects
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}
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public Key getKey() {
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return key;
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}
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public List<Greeting> getGreetings() {
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// This query requires the index defined in index.yaml to work because of the orderBy on date.
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EntityQuery query = Query.entityQueryBuilder()
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.kind("Greeting")
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.filter(hasAncestor(key))
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.orderBy(desc("date"))
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.limit(5)
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.build();
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QueryResults<Entity> results = getDatastore().run(query);
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Builder<Greeting> resultListBuilder = ImmutableList.builder();
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while (results.hasNext()) {
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resultListBuilder.add(new Greeting(results.next()));
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}
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return resultListBuilder.build();
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}
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}
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//[END all]

‎appengine/guestbook-cloud-datastore/src/main/java/com/example/guestbook/Persistence.java

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/**
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* Copyright 2016 Google Inc. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.guestbook;
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import com.google.cloud.datastore.Datastore;
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import com.google.cloud.datastore.DatastoreOptions;
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import com.google.cloud.datastore.KeyFactory;
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import java.util.concurrent.atomic.AtomicReference;
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//[START all]
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public class Persistence {
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private static AtomicReference<Datastore> datastore = new AtomicReference<>();
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public static Datastore getDatastore() {
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if (datastore.get() == null) {
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datastore.set(DatastoreOptions.builder().projectId("your-project-id-here").build().service());
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}
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return datastore.get();
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}
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public static KeyFactory getKeyFactory(Class<?> c) {
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return getDatastore().newKeyFactory().kind(c.getSimpleName());
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}
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public static void setDatastore(Datastore datastore) {
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Persistence.datastore.set(datastore);
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}
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}
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//[END all]

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