Refactor Datastore example, add example on embedded entities

gcloud-java-examples/README.md

@@ -81,6 +81,7 @@ To run examples from your command line:
     mvn exec:java -Dexec.mainClass="com.google.cloud.examples.datastore.DatastoreExample" -Dexec.args="your-project-id my_name add my\ comment"
     mvn exec:java -Dexec.mainClass="com.google.cloud.examples.datastore.DatastoreExample" -Dexec.args="your-project-id my_name display"
     mvn exec:java -Dexec.mainClass="com.google.cloud.examples.datastore.DatastoreExample" -Dexec.args="your-project-id my_name delete"
+    mvn exec:java -Dexec.mainClass="com.google.cloud.examples.datastore.DatastoreExample" -Dexec.args="your-project-id my_name set [email protected] 1234"
     ```
 
   * Here's an example run of `DnsExample`.

gcloud-java-examples/src/main/java/com/google/cloud/examples/datastore/DatastoreExample.java

@@ -38,15 +38,23 @@
 /**
  * An example of using Google Cloud Datastore.
  *
- * <p>This example adds, display or clear comments for a given user.
+ * <p>This example adds, displays or clears comments for a given user. This example also sets
+ * contact information for a user.
  *
  * <p>Steps needed for running the example:<ol>
  * <li>login using gcloud SDK - {@code gcloud auth login}.</li>
  * <li>compile using maven - {@code mvn compile}</li>
- * <li>run using maven - {@code mvn exec:java
- * -Dexec.mainClass="com.google.cloud.examples.datastore.DatastoreExample"
- * -Dexec.args="[projectId] [user] [delete|display|add comment]"}</li>
+ * <li>run using maven -
+ * <pre>{@code mvn exec:java -Dexec.mainClass="com.google.cloud.examples.datastore.DatastoreExample"
+ *  -Dexec.args="<project_id> <user>
+ *  delete |
+ *  display |
+ *  add <comment> |
+ *  set <email> <phone>}</pre>
+ * </li>
  * </ol>
+ *
+ * <p>If no action is provided {@code display} is executed.
  */
 public class DatastoreExample {
 
@@ -56,15 +64,24 @@ public class DatastoreExample {
   private static final String DEFAULT_ACTION = "display";
   private static final Map<String, DatastoreAction> ACTIONS = new HashMap<>();
 
-  private interface DatastoreAction {
-    void run(Transaction tx, Key userKey, String... args);
+  private abstract static class DatastoreAction<T> {
+
+    abstract void run(Transaction tx, Key userKey, T request) throws Exception;
 
-    String getRequiredParams();
+    abstract T parse(String... args) throws Exception;
+
+    protected String params() {
+      return "";
+    }
   }
 
-  private static class DeleteAction implements DatastoreAction {
+  /**
+   * This class demonstrates how to delete a user. This action also queries the keys of all comments
+   * associated with the user and uses them to delete comments.
+   */
+  private static class DeleteAction extends DatastoreAction<Void> {
     @Override
-    public void run(Transaction tx, Key userKey, String... args) {
+    public void run(Transaction tx, Key userKey, Void request) {
       Entity user = tx.get(userKey);
       if (user == null) {
         System.out.println("Nothing to delete, user does not exist.");
@@ -86,19 +103,29 @@ public void run(Transaction tx, Key userKey, String... args) {
     }
 
     @Override
-    public String getRequiredParams() {
-      return "";
+    Void parse(String... args) throws Exception {
+      return null;
     }
   }
 
-  private static class DisplayAction implements DatastoreAction {
+  /**
+   * This class demonstrates how to get a user. The action also queries all comments associated
+   * with the user.
+   */
+  private static class DisplayAction extends DatastoreAction<Void> {
     @Override
-    public void run(Transaction tx, Key userKey, String... args) {
+    public void run(Transaction tx, Key userKey, Void request) {
       Entity user = tx.get(userKey);
       if (user == null) {
-        System.out.println("No comments for '" + userKey.name() + "'.");
+        System.out.println("User '" + userKey.name() + "' does not exist.");
         return;
       }
+      if (user.contains("contact")) {
+        FullEntity<IncompleteKey> contact = user.getEntity("contact");
+        String email = contact.getString("email");
+        String phone = contact.getString("phone");
+        System.out.printf("User '%s' email is '%s', phone is '%s'%n", userKey.name(), email, phone);
+      }
       System.out.printf("User '%s' has %d comment[s].%n", userKey.name(), user.getLong("count"));
       int limit = 200;
       Map<DateTime, String> sortedComments = new TreeMap<>();
@@ -131,25 +158,37 @@ public void run(Transaction tx, Key userKey, String... args) {
     }
 
     @Override
-    public String getRequiredParams() {
-      return "";
+    Void parse(String... args) throws Exception {
+      return null;
     }
   }
 
-  private static class AddAction implements DatastoreAction {
+  /**
+   * This class adds a comment for a user. If the user does not exist its entity is created.
+   */
+  private static class AddCommentAction extends DatastoreAction<String> {
     @Override
-    public void run(Transaction tx, Key userKey, String... args) {
+    public void run(Transaction tx, Key userKey, String content) {
       Entity user = tx.get(userKey);
       if (user == null) {
         System.out.println("Adding a new user.");
-        user = Entity.builder(userKey)
-            .set("count", 1L)
-            .build();
+        user = Entity.builder(userKey).set("count", 1L).build();
         tx.add(user);
       } else {
         user = Entity.builder(user).set("count", user.getLong("count") + 1L).build();
         tx.update(user);
       }
+      IncompleteKey commentKey = IncompleteKey.builder(userKey, COMMENT_KIND).build();
+      FullEntity<IncompleteKey> comment = FullEntity.builder(commentKey)
+          .set("content", content)
+          .set("timestamp", DateTime.now())
+          .build();
+      tx.addWithDeferredIdAllocation(comment);
+      System.out.println("Adding a comment to user '" + userKey.name() + "'.");
+    }
+
+    @Override
+    String parse(String... args) throws Exception {
       String content = "No comment.";
       if (args.length > 0) {
         StringBuilder stBuilder = new StringBuilder();
@@ -159,28 +198,98 @@ public void run(Transaction tx, Key userKey, String... args) {
         stBuilder.setLength(stBuilder.length() - 1);
         content = stBuilder.toString();
       }
-      IncompleteKey commentKey = IncompleteKey.builder(userKey, COMMENT_KIND).build();
-      FullEntity<IncompleteKey> comment = FullEntity.builder(commentKey)
-          .set("content", content)
-          .set("timestamp", DateTime.now())
+      return content;
+    }
+
+    @Override
+    protected String params() {
+      return "<comment>";
+    }
+  }
+
+  /**
+   * This class sets contact information (email and phone) for a user. If the user does not exist
+   * its entity is created. Contact information is saved as an entity embedded in the user entity.
+   */
+  private static class SetContactAction extends DatastoreAction<SetContactAction.Contact> {
+
+    static final class Contact {
+
+      private final String email;
+      private final String phone;
+
+      Contact(String email, String phone) {
+        this.email = email;
+        this.phone = phone;
+      }
+
+      String email() {
+        return email;
+      }
+
+      String phone() {
+        return phone;
+      }
+    }
+
+    @Override
+    public void run(Transaction tx, Key userKey, Contact contact) {
+      Entity user = tx.get(userKey);
+      if (user == null) {
+        System.out.println("Adding a new user.");
+        user = Entity.builder(userKey).set("count", 0L).build();
+        tx.add(user);
+      }
+      FullEntity<IncompleteKey> contactEntity = FullEntity.builder()
+          .set("email", contact.email())
+          .set("phone", contact.phone())
           .build();
-      tx.addWithDeferredIdAllocation(comment);
-      System.out.println("Adding a comment to user '" + userKey.name() + "'.");
+      tx.update(Entity.builder(user).set("contact", contactEntity).build());
+      System.out.println("Setting contact for user '" + userKey.name() + "'.");
     }
 
     @Override
-    public String getRequiredParams() {
-      return "comment";
+    Contact parse(String... args) throws Exception {
+      String message;
+      if (args.length == 2) {
+        return new Contact(args[0], args[1]);
+      } else if (args.length > 2) {
+        message = "Too many arguments.";
+      } else {
+        message = "Missing required email and phone.";
+      }
+      throw new IllegalArgumentException(message);
+    }
+
+    @Override
+    protected String params() {
+      return "<email> <phone>";
     }
   }
 
   static {
     ACTIONS.put("delete", new DeleteAction());
-    ACTIONS.put("add", new AddAction());
+    ACTIONS.put("add", new AddCommentAction());
+    ACTIONS.put("set", new SetContactAction());
     ACTIONS.put("display", new DisplayAction());
   }
 
-  public static void main(String... args) {
+  private static void printUsage() {
+    StringBuilder actionAndParams = new StringBuilder();
+    for (Map.Entry<String, DatastoreAction> entry : ACTIONS.entrySet()) {
+      actionAndParams.append("\n\t").append(entry.getKey());
+
+      String param = entry.getValue().params();
+      if (param != null && !param.isEmpty()) {
+        actionAndParams.append(' ').append(param.replace("\n", "\n\t\t"));
+      }
+    }
+    System.out.printf("Usage: %s <project_id> <user> operation <args>*%s%n",
+        DatastoreExample.class.getSimpleName(), actionAndParams);
+  }
+
+  @SuppressWarnings("unchecked")
+  public static void main(String... args) throws Exception {
     String projectId = args.length > 0 ? args[0] : null;
     // If you want to access a local Datastore running via the Google Cloud SDK, do
     //   DatastoreOptions options = DatastoreOptions.builder()
@@ -197,24 +306,26 @@ public static void main(String... args) {
     String actionName = args.length > 2 ? args[2].toLowerCase() : DEFAULT_ACTION;
     DatastoreAction action = ACTIONS.get(actionName);
     if (action == null) {
-      StringBuilder actionAndParams = new StringBuilder();
-      for (Map.Entry<String, DatastoreAction> entry : ACTIONS.entrySet()) {
-        actionAndParams.append(entry.getKey());
-        String param = entry.getValue().getRequiredParams();
-        if (param != null && !param.isEmpty()) {
-          actionAndParams.append(' ').append(param);
-        }
-        actionAndParams.append('|');
-      }
-      actionAndParams.setLength(actionAndParams.length() - 1);
-      System.out.printf("Usage: %s [projectId] [user] [%s]%n",
-          DatastoreExample.class.getSimpleName(), actionAndParams);
+      System.out.println("Unrecognized action.");
+      printUsage();
       return;
     }
     args = args.length > 3 ? Arrays.copyOfRange(args, 3, args.length) : new String []{};
     Transaction tx = datastore.newTransaction();
+    Object request;
+    try {
+      request = action.parse(args);
+    } catch (IllegalArgumentException ex) {
+      System.out.println("Invalid input for action '" + actionName + "'. " + ex.getMessage());
+      System.out.println("Expected: " + action.params());
+      return;
+    } catch (Exception ex) {
+      System.out.println("Failed to parse request.");
+      ex.printStackTrace();
+      return;
+    }
     try {
-      action.run(tx, key, args);
+      action.run(tx, key, request);
       tx.commit();
     } finally {
       if (tx.active()) {