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Alexandre Dutraolim7t
Alexandre Dutra
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JAVA-1237: Add JSR-353 JSON examples
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‎driver-examples/pom.xml‎

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<optional>true</optional>
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</dependency>
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<dependency>
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<groupId>javax.json</groupId>
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<artifactId>javax.json-api</artifactId>
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<version>${jsr353-api.version}</version>
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<optional>true</optional>
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</dependency>
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<dependency>
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<groupId>org.glassfish</groupId>
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<artifactId>javax.json</artifactId>
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<version>${jsr353-ri.version}</version>
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<optional>true</optional>
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<scope>runtime</scope>
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</dependency>
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<!-- driver logs -->
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<dependency>
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<groupId>ch.qos.logback</groupId>

‎driver-examples/src/main/java/com/datastax/driver/examples/json/Jsr353JsonColumn.java‎

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/*
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* Copyright (C) 2012-2015 DataStax Inc.
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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.datastax.driver.examples.json;
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import com.datastax.driver.core.*;
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import com.datastax.driver.extras.codecs.json.Jsr353JsonCodec;
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import javax.json.Json;
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import javax.json.JsonObject;
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import javax.json.JsonStructure;
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import static com.datastax.driver.core.querybuilder.QueryBuilder.*;
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/**
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* Illustrates how to map a single table column of type {@code VARCHAR},
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* containing JSON payloads, into a Java object using
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* the <a href="https://jcp.org/en/jsr/detail?id=353">Java API for JSON processing</a>.
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* <p/>
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* This example makes usage of a custom {@link TypeCodec codec},
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* {@link Jsr353JsonCodec}, which is declared in the driver-extras module.
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* If you plan to follow this example, make sure to include the following
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* Maven dependencies in your project:
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* <pre>{@code
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* <dependency>
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* <groupId>com.datastax.cassandra</groupId>
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* <artifactId>cassandra-driver-extras</artifactId>
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* <version>${driver.version}</version>
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* </dependency>
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*
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* <dependency>
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* <groupId>javax.json</groupId>
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* <artifactId>javax.json-api</artifactId>
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* <version>${jsr353-api.version}</version>
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* </dependency>
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*
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* <dependency>
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* <groupId>org.glassfish</groupId>
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* <artifactId>javax.json</artifactId>
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* <version>${jsr353-ri.version}</version>
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* <scope>runtime</scope>
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* </dependency>
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* }</pre>
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* This example also uses the {@link com.datastax.driver.core.querybuilder.QueryBuilder QueryBuilder};
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* for examples using the "core" API, see {@link PlainTextJson} (they are easily translatable to the
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* queries in this class).
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* <p/>
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* Preconditions:
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* - a Cassandra cluster is running and accessible through the contacts points identified by CONTACT_POINTS and PORT;
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* <p/>
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* Side effects:
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* - creates a new keyspace "examples" in the cluster. If a keyspace with this name already exists, it will be reused;
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* - creates a table "examples.json_jsr353_column". If it already exists, it will be reused;
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* - inserts data in the table.
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*/
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public class Jsr353JsonColumn {
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static String[] CONTACT_POINTS = {"127.0.0.1"};
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static int PORT = 9042;
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public static void main(String[] args) {
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Cluster cluster = null;
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try {
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// A codec to convert JSON payloads into JsonObject instances;
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// this codec is declared in the driver-extras module
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Jsr353JsonCodec userCodec = new Jsr353JsonCodec();
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cluster = Cluster.builder()
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.addContactPoints(CONTACT_POINTS).withPort(PORT)
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.withCodecRegistry(new CodecRegistry().register(userCodec))
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.build();
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Session session = cluster.connect();
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createSchema(session);
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insertJsonColumn(session);
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selectJsonColumn(session);
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} finally {
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if (cluster != null) cluster.close();
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}
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}
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private static void createSchema(Session session) {
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session.execute("CREATE KEYSPACE IF NOT EXISTS examples " +
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"WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1}");
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session.execute("CREATE TABLE IF NOT EXISTS examples.json_jsr353_column(" +
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"id int PRIMARY KEY, json text)");
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}
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// Mapping a JSON object to a table column
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private static void insertJsonColumn(Session session) {
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JsonObject alice = Json.createObjectBuilder()
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.add("name", "alice")
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.add("age", 30)
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.build();
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JsonObject bob = Json.createObjectBuilder()
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.add("name", "bob")
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.add("age", 35)
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.build();
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// Build and execute a simple statement
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Statement stmt = insertInto("examples", "json_jsr353_column")
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.value("id", 1)
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// the JSON object will be converted into a String and persisted into the VARCHAR column "json"
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.value("json", alice);
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session.execute(stmt);
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// The JSON object can be a bound value if the statement is prepared
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// (we use a local variable here for the sake of example, but in a real application you would cache and reuse
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// the prepared statement)
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PreparedStatement pst = session.prepare(
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insertInto("examples", "json_jsr353_column")
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.value("id", bindMarker("id"))
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.value("json", bindMarker("json")));
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session.execute(pst.bind()
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.setInt("id", 2)
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// note that the codec requires that the type passed to the set() method
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// be always JsonStructure, and not a subclass of it, such as JsonObject
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.set("json", bob, JsonStructure.class));
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}
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// Retrieving JSON objects from a table column
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private static void selectJsonColumn(Session session) {
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Statement stmt = select()
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.from("examples", "json_jsr353_column")
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.where(in("id", 1, 2));
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ResultSet rows = session.execute(stmt);
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for (Row row : rows) {
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int id = row.getInt("id");
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// retrieve the JSON payload and convert it to a JsonObject instance
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// note that the codec requires that the type passed to the get() method
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// be always JsonStructure, and not a subclass of it, such as JsonObject,
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// hence the need to downcast to JsonObject manually
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JsonObject user = (JsonObject) row.get("json", JsonStructure.class);
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// it is also possible to retrieve the raw JSON payload
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String json = row.getString("json");
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System.out.printf("Retrieved row:%n" +
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"id %d%n" +
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"user %s%n" +
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"user (raw) %s%n%n",
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id, user, json);
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}
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}
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}

‎driver-examples/src/main/java/com/datastax/driver/examples/json/Jsr353JsonFunction.java‎

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/*
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* Copyright (C) 2012-2015 DataStax Inc.
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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.datastax.driver.examples.json;
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import com.datastax.driver.core.*;
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import com.datastax.driver.extras.codecs.json.Jsr353JsonCodec;
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import javax.json.Json;
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import javax.json.JsonObject;
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import javax.json.JsonStructure;
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import static com.datastax.driver.core.querybuilder.QueryBuilder.*;
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/**
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* Illustrates how to map a single table column of an arbitrary type
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* to a Java object using
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* the <a href="https://jcp.org/en/jsr/detail?id=353">Java API for JSON processing</a>,
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* and leveraging the {@code toJson()} and {@code fromJson()} functions
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* introduced in Cassandra 2.2.
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* <p/>
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* This example makes usage of a custom {@link TypeCodec codec},
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* {@link Jsr353JsonCodec}, which is declared in the driver-extras module.
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* If you plan to follow this example, make sure to include the following
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* Maven dependencies in your project:
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* <pre>{@code
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* <dependency>
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* <groupId>com.datastax.cassandra</groupId>
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* <artifactId>cassandra-driver-extras</artifactId>
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* <version>${driver.version}</version>
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* </dependency>
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*
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* <dependency>
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* <groupId>javax.json</groupId>
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* <artifactId>javax.json-api</artifactId>
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* <version>${jsr353-api.version}</version>
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* </dependency>
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*
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* <dependency>
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* <groupId>org.glassfish</groupId>
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* <artifactId>javax.json</artifactId>
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* <version>${jsr353-ri.version}</version>
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* <scope>runtime</scope>
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* </dependency>
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* }</pre>
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* This example also uses the {@link com.datastax.driver.core.querybuilder.QueryBuilder QueryBuilder};
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* for examples using the "core" API, see {@link PlainTextJson} (they are easily translatable to the
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* queries in this class).
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* <p/>
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* Preconditions:
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* - a Cassandra cluster is running and accessible through the contacts points identified by CONTACT_POINTS and PORT;
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* <p/>
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* Side effects:
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* - creates a new keyspace "examples" in the cluster. If a keyspace with this name already exists, it will be reused;
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* - creates a user-defined type (UDT) "examples.json_jsr353_function_user". If it already exists, it will be reused;
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* - creates a table "examples.json_jsr353_function". If it already exists, it will be reused;
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* - inserts data in the table.
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*
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* @see <a href="http://www.datastax.com/dev/blog/whats-new-in-cassandra-2-2-json-support">What’s New in Cassandra 2.2: JSON Support</a>
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*/
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public class Jsr353JsonFunction {
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static String[] CONTACT_POINTS = {"127.0.0.1"};
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static int PORT = 9042;
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public static void main(String[] args) {
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Cluster cluster = null;
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try {
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// A codec to convert JSON payloads into JsonObject instances;
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// this codec is declared in the driver-extras module
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Jsr353JsonCodec userCodec = new Jsr353JsonCodec();
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cluster = Cluster.builder()
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.addContactPoints(CONTACT_POINTS).withPort(PORT)
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.withCodecRegistry(new CodecRegistry()
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.register(userCodec))
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.build();
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Session session = cluster.connect();
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createSchema(session);
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insertFromJson(session);
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selectToJson(session);
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} finally {
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if (cluster != null) cluster.close();
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}
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}
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private static void createSchema(Session session) {
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session.execute("CREATE KEYSPACE IF NOT EXISTS examples " +
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"WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1}");
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session.execute("CREATE TYPE IF NOT EXISTS examples.json_jsr353_function_user(" +
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"name text, age int)");
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session.execute("CREATE TABLE IF NOT EXISTS examples.json_jsr353_function(" +
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"id int PRIMARY KEY, user frozen<json_jsr353_function_user>, scores map<varchar,float>)");
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}
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// Mapping JSON payloads to table columns of arbitrary types,
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// using fromJson() function
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private static void insertFromJson(Session session) {
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JsonObject alice = Json.createObjectBuilder()
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.add("name", "alice")
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.add("age", 30)
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.build();
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JsonObject bob = Json.createObjectBuilder()
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.add("name", "bob")
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.add("age", 35)
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.build();
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JsonObject aliceScores = Json.createObjectBuilder()
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.add("call_of_duty", 4.8)
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.add("pokemon_go", 9.7)
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.build();
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JsonObject bobScores = Json.createObjectBuilder()
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.add("zelda", 8.3)
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.add("pokemon_go", 12.4)
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.build();
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// Build and execute a simple statement
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Statement stmt = insertInto("examples", "json_jsr353_function")
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.value("id", 1)
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// client-side, the JsonObject will be converted into a JSON String;
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// then, server-side, the fromJson() function will convert that JSON string
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// into an instance of the json_jsr353_function_user user-defined type (UDT),
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// which will be persisted into the column "user"
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.value("user", fromJson(alice))
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// same thing, but this time converting from
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// a JsonObject to a JSON string, then from this string to a map<varchar,float>
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.value("scores", fromJson(aliceScores));
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session.execute(stmt);
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// The JSON object can be a bound value if the statement is prepared
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// (we use a local variable here for the sake of example, but in a real application you would cache and reuse
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// the prepared statement)
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PreparedStatement pst = session.prepare(
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insertInto("examples", "json_jsr353_function")
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.value("id", bindMarker("id"))
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.value("user", fromJson(bindMarker("user")))
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.value("scores", fromJson(bindMarker("scores"))));
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session.execute(pst.bind()
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.setInt("id", 2)
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// note that the codec requires that the type passed to the set() method
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// be always JsonStructure, and not a subclass of it, such as JsonObject
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.set("user", bob, JsonStructure.class)
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.set("scores", bobScores, JsonStructure.class));
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}
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// Retrieving JSON payloads from table columns of arbitrary types,
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// using toJson() function
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private static void selectToJson(Session session) {
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Statement stmt = select()
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.column("id")
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.toJson("user").as("user")
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.toJson("scores").as("scores")
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.from("examples", "json_jsr353_function")
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.where(in("id", 1, 2));
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ResultSet rows = session.execute(stmt);
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for (Row row : rows) {
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int id = row.getInt("id");
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// retrieve the JSON payload and convert it to a JsonObject instance
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// note that the codec requires that the type passed to the get() method
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// be always JsonStructure, and not a subclass of it, such as JsonObject,
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// hence the need to downcast to JsonObject manually
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JsonObject user = (JsonObject) row.get("user", JsonStructure.class);
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// it is also possible to retrieve the raw JSON payload
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String userJson = row.getString("user");
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// retrieve the JSON payload and convert it to a JsonObject instance
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JsonObject scores = (JsonObject) row.get("scores", JsonStructure.class);
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// it is also possible to retrieve the raw JSON payload
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String scoresJson = row.getString("scores");
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System.out.printf("Retrieved row:%n" +
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"id %d%n" +
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"user %s%n" +
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"user (raw) %s%n" +
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"scores %s%n" +
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"scores (raw) %s%n%n",
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id, user, userJson, scores, scoresJson);
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}
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}
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}

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