#361 - Add example for MongoDB 4.0 transactions.

mongodb/transactions/src/main/java/example/springdata/mongodb/Process.java

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+/*
+ * Copyright 2018 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
+ *
+ *      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.
+ */
+package example.springdata.mongodb;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.mongodb.core.mapping.Document;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+@Data
+@AllArgsConstructor
+@Document("processes")
+public class Process {
+
+	@Id Integer id;
+	State state;
+	int transitionCount;
+
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/State.java

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+/*
+ * Copyright 2018 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
+ *
+ *      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.
+ */
+package example.springdata.mongodb;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+public enum State {
+
+	CREATED, ACTIVE, DONE
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/reactive/ReactiveProcessRepository.java

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+/*
+ * Copyright 2018 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
+ *
+ *      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.
+ */
+package example.springdata.mongodb.reactive;
+
+import example.springdata.mongodb.Process;
+
+import org.springframework.data.repository.reactive.ReactiveCrudRepository;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+public interface ReactiveProcessRepository extends ReactiveCrudRepository<Process, Integer> {
+
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/reactive/ReactiveTransitionService.java

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+/*
+ * Copyright 2018 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
+ *
+ *      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.
+ */
+package example.springdata.mongodb.reactive;
+
+import example.springdata.mongodb.Process;
+import example.springdata.mongodb.State;
+import lombok.RequiredArgsConstructor;
+import reactor.core.publisher.Mono;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.springframework.data.mongodb.core.ReactiveMongoOperations;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.Update;
+import org.springframework.stereotype.Service;
+import org.springframework.util.Assert;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+@Service
+@RequiredArgsConstructor
+public class ReactiveTransitionService {
+
+	final ReactiveProcessRepository repository;
+	final ReactiveMongoTemplate template;
+
+	final AtomicInteger counter = new AtomicInteger(0);
+
+	public Mono<Process> newProcess() {
+		return repository.save(new Process(counter.incrementAndGet(), State.CREATED, 0));
+	}
+
+	public Mono<Integer> run(Integer id) {
+
+		return template.inTransaction().execute(action -> {
+
+			return lookup(id) //
+					.flatMap(process -> start(action, process)) //
+					.flatMap(this::verify) //
+					.flatMap(process -> finish(action, process));
+
+		}).next().map(Process::getId);
+	}
+
+	private Mono<Process> finish(ReactiveMongoOperations operations, Process process) {
+
+		return operations.update(Process.class).matching(Query.query(Criteria.where("id").is(process.getId())))
+				.apply(Update.update("state", State.DONE).inc("transitionCount", 1)).first() //
+				.then(Mono.just(process));
+	}
+
+	Mono<Process> start(ReactiveMongoOperations operations, Process process) {
+
+		return operations.update(Process.class).matching(Query.query(Criteria.where("id").is(process.getId())))
+				.apply(Update.update("state", State.ACTIVE).inc("transitionCount", 1)).first() //
+				.then(Mono.just(process));
+	}
+
+	Mono<Process> lookup(Integer id) {
+		return repository.findById(id);
+	}
+
+	Mono<Process> verify(Process process) {
+
+		Assert.state(process.getId() % 3 != 0, "We're sorry but we needed to drop that one");
+		return Mono.just(process);
+	}
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/sync/ProcessRepository.java

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+/*
+ * Copyright 2018 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
+ *
+ *      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.
+ */
+package example.springdata.mongodb.sync;
+
+import example.springdata.mongodb.Process;
+
+import org.springframework.data.repository.CrudRepository;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+interface ProcessRepository extends CrudRepository<Process, Integer> {
+
+}

mongodb/transactions/src/main/java/example/springdata/mongodb/sync/TransitionService.java

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+/*
+ * Copyright 2018 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
+ *
+ *      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.
+ */
+package example.springdata.mongodb.sync;
+
+import example.springdata.mongodb.Process;
+import example.springdata.mongodb.State;
+import lombok.RequiredArgsConstructor;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.Update;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.Assert;
+
+/**
+ * @author Christoph Strobl
+ * @currentRead The Core - Peter V. Brett
+ */
+@Service
+@RequiredArgsConstructor
+class TransitionService {
+
+	final ProcessRepository repository;
+	final MongoTemplate template;
+
+	final AtomicInteger counter = new AtomicInteger(0);
+
+	public Process newProcess() {
+		return repository.save(new Process(counter.incrementAndGet(), State.CREATED, 0));
+	}
+
+	@Transactional
+	public void run(Integer id) {
+
+		Process process = lookup(id);
+
+		if (!State.CREATED.equals(process.getState())) {
+			return;
+		}
+
+		start(process);
+		verify(process);
+		finish(process);
+	}
+
+	private void finish(Process process) {
+
+		template.update(Process.class).matching(Query.query(Criteria.where("id").is(process.getId())))
+				.apply(Update.update("state", State.DONE).inc("transitionCount", 1)).first();
+	}
+
+	void start(Process process) {
+
+		template.update(Process.class).matching(Query.query(Criteria.where("id").is(process.getId())))
+				.apply(Update.update("state", State.ACTIVE).inc("transitionCount", 1)).first();
+	}
+
+	Process lookup(Integer id) {
+		return repository.findById(id).get();
+	}
+
+	void verify(Process process) {
+		Assert.state(process.getId() % 3 != 0, "We're sorry but we needed to drop that one");
+	}
+}