#318 - Add support for Postgres JSON type.

We now pass-thru Postgres's JSON type that can be used in entities and simple queries.

src/main/java/org/springframework/data/r2dbc/dialect/PostgresDialect.java

@@ -22,8 +22,20 @@ import org.springframework.util.ClassUtils;
 public class PostgresDialect extends org.springframework.data.relational.core.dialect.PostgresDialect
 		implements R2dbcDialect {
 
-	private static final Set<Class<?>> SIMPLE_TYPES = new HashSet<>(
-			Arrays.asList(UUID.class, URL.class, URI.class, InetAddress.class));
+	private static final Set<Class<?>> SIMPLE_TYPES;
+
+	static {
+
+		Set<Class<?>> simpleTypes = new HashSet<>(Arrays.asList(UUID.class, URL.class, URI.class, InetAddress.class));
+
+		if (ClassUtils.isPresent("io.r2dbc.postgresql.codec.Json", PostgresDialect.class.getClassLoader())) {
+
+			simpleTypes
+					.add(ClassUtils.resolveClassName("io.r2dbc.postgresql.codec.Json", PostgresDialect.class.getClassLoader()));
+		}
+
+		SIMPLE_TYPES = simpleTypes;
+	}
 
 	/**
 	 * Singleton instance.

src/test/java/org/springframework/data/r2dbc/convert/PostgresMappingR2dbcConverterUnitTests.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2019-2020 the original author or authors.
+ *
+ * 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
+ *
+ *      https://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.
+ */
+package org.springframework.data.r2dbc.convert;
+
+import static org.assertj.core.api.Assertions.*;
+
+import io.r2dbc.postgresql.codec.Json;
+import lombok.AllArgsConstructor;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.convert.CustomConversions;
+import org.springframework.data.r2dbc.dialect.PostgresDialect;
+import org.springframework.data.r2dbc.mapping.OutboundRow;
+import org.springframework.data.r2dbc.mapping.R2dbcMappingContext;
+import org.springframework.data.r2dbc.mapping.SettableValue;
+import org.springframework.data.relational.core.mapping.RelationalMappingContext;
+import org.springframework.data.relational.core.sql.SqlIdentifier;
+
+/**
+ * Postgres-specific unit tests for {@link MappingR2dbcConverter}.
+ *
+ * @author Mark Paluch
+ */
+public class PostgresMappingR2dbcConverterUnitTests {
+
+	RelationalMappingContext mappingContext = new R2dbcMappingContext();
+	MappingR2dbcConverter converter = new MappingR2dbcConverter(mappingContext);
+
+	@Before
+	public void before() {
+
+		List<Object> converters = new ArrayList<>(PostgresDialect.INSTANCE.getConverters());
+		converters.addAll(R2dbcCustomConversions.STORE_CONVERTERS);
+		CustomConversions.StoreConversions storeConversions = CustomConversions.StoreConversions
+				.of(PostgresDialect.INSTANCE.getSimpleTypeHolder(), converters);
+
+		R2dbcCustomConversions customConversions = new R2dbcCustomConversions(storeConversions, Collections.emptyList());
+
+		mappingContext.setSimpleTypeHolder(customConversions.getSimpleTypeHolder());
+
+		converter = new MappingR2dbcConverter(mappingContext, customConversions);
+	}
+
+	@Test // gh-318
+	public void shouldPassThruJson() {
+
+		JsonPerson person = new JsonPerson(null, Json.of("{\"hello\":\"world\"}"));
+
+		OutboundRow row = new OutboundRow();
+		converter.write(person, row);
+
+		assertThat(row).containsEntry(SqlIdentifier.unquoted("json_value"), SettableValue.from(person.jsonValue));
+	}
+
+	@AllArgsConstructor
+	static class JsonPerson {
+
+		@Id Long id;
+
+		Json jsonValue;
+	}
+}

src/test/java/org/springframework/data/r2dbc/repository/PostgresR2dbcRepositoryIntegrationTests.java

@@ -15,24 +15,34 @@
  */
 package org.springframework.data.r2dbc.repository;
 
+import static org.assertj.core.api.Assertions.*;
+
+import io.r2dbc.postgresql.codec.Json;
 import io.r2dbc.spi.ConnectionFactory;
+import lombok.AllArgsConstructor;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
 
 import javax.sql.DataSource;
 
 import org.junit.ClassRule;
+import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan.Filter;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.FilterType;
+import org.springframework.data.annotation.Id;
 import org.springframework.data.r2dbc.config.AbstractR2dbcConfiguration;
 import org.springframework.data.r2dbc.repository.config.EnableR2dbcRepositories;
 import org.springframework.data.r2dbc.repository.support.R2dbcRepositoryFactory;
 import org.springframework.data.r2dbc.testing.ExternalDatabase;
 import org.springframework.data.r2dbc.testing.PostgresTestSupport;
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringRunner;
 
@@ -47,9 +57,12 @@ public class PostgresR2dbcRepositoryIntegrationTests extends AbstractR2dbcReposi
 
 	@ClassRule public static final ExternalDatabase database = PostgresTestSupport.database();
 
+	@Autowired JsonPersonRepository jsonPersonRepository;
+
 	@Configuration
 	@EnableR2dbcRepositories(considerNestedRepositories = true,
-			includeFilters = @Filter(classes = PostgresLegoSetRepository.class, type = FilterType.ASSIGNABLE_TYPE))
+			includeFilters = @Filter(classes = { PostgresLegoSetRepository.class, JsonPersonRepository.class },
+					type = FilterType.ASSIGNABLE_TYPE))
 	static class IntegrationTestConfiguration extends AbstractR2dbcConfiguration {
 
 		@Bean
@@ -93,4 +106,37 @@ public class PostgresR2dbcRepositoryIntegrationTests extends AbstractR2dbcReposi
 		@Query("SELECT id FROM legoset")
 		Flux<Integer> findAllIds();
 	}
+
+	@Test
+	public void shouldSaveAndLoadJson() {
+
+		JdbcTemplate template = new JdbcTemplate(createDataSource());
+
+		template.execute("DROP TABLE IF EXISTS json_person");
+		template.execute("CREATE TABLE json_person (\n" //
+				+ "    id          SERIAL PRIMARY KEY,\n" //
+				+ "    json_value  JSONB NOT NULL" //
+				+ ");");
+
+		JsonPerson person = new JsonPerson(null, Json.of("{\"hello\": \"world\"}"));
+		jsonPersonRepository.save(person).as(StepVerifier::create).expectNextCount(1).verifyComplete();
+
+		jsonPersonRepository.findAll().as(StepVerifier::create).consumeNextWith(actual -> {
+
+			assertThat(actual.jsonValue).isNotNull();
+			assertThat(actual.jsonValue.asString()).isEqualTo("{\"hello\": \"world\"}");
+		}).verifyComplete();
+	}
+
+	@AllArgsConstructor
+	static class JsonPerson {
+
+		@Id Long id;
+
+		Json jsonValue;
+	}
+
+	interface JsonPersonRepository extends ReactiveCrudRepository<JsonPerson, Long> {
+
+	}
 }