spanner: Add snippets for ReadContext

google-cloud-clients/google-cloud-spanner/src/main/java/com/google/cloud/spanner/ReadContext.java

@@ -43,7 +43,18 @@ enum QueryAnalyzeMode {
    * to the first {@link ResultSet#next()} call. Regardless of blocking behavior, any {@link
    * SpannerException} is deferred to the first or subsequent {@link ResultSet#next()} call.
    *
-   * <p>TODO(user): Code examples.
+   * <!--SNIPPET read_context_read-->
+   * <pre>{@code
+   * ReadContext readContext = dbClient.singleUse();
+   * ResultSet resultSet =
+   *     readContext.read(
+   *         "Albums",
+   *         // KeySet.all() can be used to read all rows in a table. KeySet exposes other
+   *         // methods to read only a subset of the table.
+   *         KeySet.all(),
+   *         Arrays.asList("SingerId", "AlbumId", "AlbumTitle"));
+   * }</pre>
+   * <!--SNIPPET read_context_read-->
    *
    * @param table the name of the table to read
    * @param keys the keys and ranges of rows to read. Regardless of ordering in {@code keys}, rows
@@ -61,6 +72,15 @@ enum QueryAnalyzeMode {
    * to the first {@link ResultSet#next()} call. Regardless of blocking behavior, any {@link
    * SpannerException} is deferred to the first or subsequent {@link ResultSet#next()} call.
    *
+   * <!--SNIPPET read_context_read_index-->
+   * <pre>{@code
+   * ReadContext readContext = dbClient.singleUse();
+   * Struct row =
+   *     readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
+   *         Arrays.asList("AlbumId", "AlbumTitle"));
+   * }</pre>
+   * <!--SNIPPET read_context_read_index-->
+   *
    * @param table the name of the table to read
    * @param index the name of the index on {@code table} to use
    * @param keys the keys and ranges of index rows to read. Regardless of ordering in {@code keys},
@@ -74,6 +94,14 @@ ResultSet readUsingIndex(
   /**
    * Reads a single row from a database, returning {@code null} if the row does not exist.
    *
+   * <!--SNIPPET read_context_read_row-->
+   * <pre>{@code
+   * ReadContext readContext = dbClient.singleUse();
+   * Struct row =
+   *     readContext.readRow("Albums", Key.of(2, 1), Arrays.asList("MarketingBudget"));
+   * }</pre>
+   * <!--SNIPPET read_context_read_row-->
+   *
    * @param table the name of the table to read
    * @param key the row to read
    * @param columns the columns to return
@@ -85,6 +113,15 @@ ResultSet readUsingIndex(
    * Reads a single row from a database using an index, returning {@code null} if the row does not
    * exist.
    *
+   * <!--SNIPPET read_context_read_index-->
+   * <pre>{@code
+   * ReadContext readContext = dbClient.singleUse();
+   * Struct row =
+   *     readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
+   *         Arrays.asList("AlbumId", "AlbumTitle"));
+   * }</pre>
+   * <!--SNIPPET read_context_read_index-->
+   *
    * @param table the name of the table to read
    * @param index the name of the index on {@code table} to use
    * @param key the index row to read
@@ -101,6 +138,18 @@ ResultSet readUsingIndex(
    * is deferred to the first {@link ResultSet#next()} call. Regardless of blocking behavior, any
    * {@link SpannerException} is deferred to the first or subsequent {@link ResultSet#next()} call.
    *
+   * <!--SNIPPET read_context_execute_query-->
+   * <pre>{@code
+   * // Rows without an explicit value for MarketingBudget will have a MarketingBudget equal to
+   * // null.
+   * ReadContext readContext = dbClient.singleUse();
+   * ResultSet resultSet =
+   *     readContext.executeQuery(
+   *         Statement.of(
+   *             "SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime FROM Albums"));
+   * }</pre>
+   * <!--SNIPPET read_context_execute_query-->
+   *
    * @param statement the query statement to execute
    * @param options the options to configure the query
    */
@@ -113,6 +162,21 @@ ResultSet readUsingIndex(
    * com.google.spanner.v1.ResultSetStats} that can be accessed by calling {@link
    * ResultSet#getStats()} on the returned {@code ResultSet}.
    *
+   * <!--SNIPPET read_context_analyze_query-->
+   * <pre>{@code
+   * ReadContext rc = dbClient.singleUse();
+   * ResultSet resultSet =
+   *     rc.analyzeQuery(
+   *         Statement.of("SELECT SingerId, AlbumId, MarketingBudget FROM Albums"),
+   *         ReadContext.QueryAnalyzeMode.PROFILE);
+   * while (resultSet.next()) {
+   *   // Discard the results. We're only processing because getStats() below requires it.
+   *   resultSet.getCurrentRowAsStruct();
+   * }
+   * ResultSetStats stats = resultSet.getStats();
+   * }</pre>
+   * <!--SNIPPET read_context_analyze_query-->
+   *
    * @param statement the query statement to execute
    * @param queryMode the mode in which to execute the query
    */

google-cloud-examples/src/main/java/com/google/cloud/examples/spanner/snippets/ReadContextSnippets.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2018 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.
+ */
+
+/*
+ * EDITING INSTRUCTIONS
+ * This file is referenced in spanner/ReadContext's javadoc. Any change
+ * to this file should be reflected in spanner/ReadContext's javadoc.
+ */
+
+package com.google.cloud.examples.spanner.snippets;
+
+import com.google.cloud.spanner.DatabaseClient;
+import com.google.cloud.spanner.Key;
+import com.google.cloud.spanner.KeySet;
+import com.google.cloud.spanner.ReadContext;
+import com.google.cloud.spanner.ResultSet;
+import com.google.cloud.spanner.Statement;
+import com.google.cloud.spanner.Struct;
+import com.google.spanner.v1.ResultSetStats;
+import java.util.Arrays;
+
+/**
+ * This class contains snippets for {@link com.google.cloud.spanner.ReadContext} interface.
+ */
+public class ReadContextSnippets {
+  private final DatabaseClient dbClient;
+
+  public ReadContextSnippets(DatabaseClient dbClient) {
+    this.dbClient = dbClient;
+  }
+
+  ResultSet read() {
+    // [START read_context_read]
+    ReadContext readContext = dbClient.singleUse();
+    ResultSet resultSet =
+        readContext.read(
+            "Albums",
+            // KeySet.all() can be used to read all rows in a table. KeySet exposes other
+            // methods to read only a subset of the table.
+            KeySet.all(),
+            Arrays.asList("SingerId", "AlbumId", "AlbumTitle"));
+    // [END read_context_read]
+
+    return resultSet;
+  }
+
+  ResultSet readUsingIndex() {
+    // [START read_context_read_index]
+    ReadContext readContext = dbClient.singleUse();
+    ResultSet resultSet =
+        readContext.readUsingIndex(
+            "Albums",
+            "AlbumsByAlbumTitle",
+            KeySet.all(),
+            Arrays.asList("AlbumId", "AlbumTitle"));
+    // [END read_context_read_index]
+
+    return resultSet;
+  }
+
+  Struct readRow() {
+    // [START read_context_read_row]
+    ReadContext readContext = dbClient.singleUse();
+    Struct row =
+        readContext.readRow("Albums", Key.of(2, 1), Arrays.asList("MarketingBudget"));
+    // [END read_context_read_row]
+
+    return row;
+  }
+
+  Struct readRowUsingIndex() {
+    // [START read_context_read_index]
+    ReadContext readContext = dbClient.singleUse();
+    Struct row =
+        readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
+            Arrays.asList("AlbumId", "AlbumTitle"));
+    // [END read_context_read_index]
+
+    return row;
+  }
+
+  ResultSet executeQuery() {
+    // [START read_context_execute_query]
+    // Rows without an explicit value for MarketingBudget will have a MarketingBudget equal to
+    // null.
+    ReadContext readContext = dbClient.singleUse();
+    ResultSet resultSet =
+        readContext.executeQuery(
+            Statement.of(
+                "SELECT SingerId, AlbumId, MarketingBudget, LastUpdateTime FROM Albums"));
+    // [END read_context_execute_query]
+    return resultSet;
+  }
+
+  ResultSetStats analyzeQuery() {
+    // [START read_context_analyze_query]
+    ReadContext rc = dbClient.singleUse();
+    ResultSet resultSet =
+        rc.analyzeQuery(
+            Statement.of("SELECT SingerId, AlbumId, MarketingBudget FROM Albums"),
+            ReadContext.QueryAnalyzeMode.PROFILE);
+    while (resultSet.next()) {
+      // Discard the results. We're only processing because getStats() below requires it.
+      resultSet.getCurrentRowAsStruct();
+    }
+    ResultSetStats stats = resultSet.getStats();
+    // [END read_context_analyze_query]
+    return stats;
+  }
+}
+