TODO(user): Code examples. + * + *
{@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"));
+ * }
+ *
*
* @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.
*
+ *
+ * {@code
+ * ReadContext readContext = dbClient.singleUse();
+ * Struct row =
+ * readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
+ * Arrays.asList("AlbumId", "AlbumTitle"));
+ * }
+ *
+ *
* @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.
*
+ *
+ * {@code
+ * ReadContext readContext = dbClient.singleUse();
+ * Struct row =
+ * readContext.readRow("Albums", Key.of(2, 1), Arrays.asList("MarketingBudget"));
+ * }
+ *
+ *
* @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.
*
+ *
+ * {@code
+ * ReadContext readContext = dbClient.singleUse();
+ * Struct row =
+ * readContext.readRowUsingIndex("Albums", "AlbumsByAlbumId", Key.of(1, "Green"),
+ * Arrays.asList("AlbumId", "AlbumTitle"));
+ * }
+ *
+ *
* @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.
*
+ *
+ * {@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"));
+ * }
+ *
+ *
* @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}.
*
+ *
+ * {@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();
+ * }
+ *
+ *
* @param statement the query statement to execute
* @param queryMode the mode in which to execute the query
*/
diff --git a/google-cloud-examples/src/main/java/com/google/cloud/examples/spanner/snippets/ReadContextSnippets.java b/google-cloud-examples/src/main/java/com/google/cloud/examples/spanner/snippets/ReadContextSnippets.java
new file mode 100644
index 000000000000..3aecca889d0d
--- /dev/null
+++ b/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;
+ }
+}
+