Introduction à Spring Data MongoDB

1. Vue d'ensemble

Cet article sera une introduction rapide et pratique à Spring Data MongoDB .

Nous allons passer en revue les bases en utilisant à la fois MongoTemplate et MongoRepository en utilisant des exemples pratiques pour illustrer chaque opération.

2. MongoTemplate et MongoRepository

Le MongoTemplate suit le modèle de modèle standard de Spring et fournit une API de base prête à l'emploi au moteur de persistance sous-jacent.

Le référentiel suit l'approche centrée sur Spring Data et est livré avec des opérations d'API plus flexibles et complexes, basées sur les modèles d'accès bien connus dans tous les projets Spring Data.

Pour les deux, nous devons commencer par définir la dépendance - par exemple, dans le pom.xml , avec Maven:

 org.springframework.data spring-data-mongodb 3.0.3.RELEASE 

Pour vérifier si une nouvelle version de la bibliothèque a été publiée, suivez les versions ici.

3. Configuration pour MongoTemplate

3.1. Configuration XML

Commençons par la configuration XML simple du modèle Mongo:

Tout d'abord, nous devons définir le bean factory responsable de la création des instances Mongo.

Ensuite, nous devons définir (et configurer) le bean modèle:

Et enfin, nous devons définir un post-processeur pour traduire toutes les MongoExceptions lancées dans les classes annotées @Repository :

3.2. Configuration Java

Créons maintenant une configuration similaire à l'aide de Java config en étendant la classe de base pour la configuration MongoDB AbstractMongoConfiguration :

@Configuration public class MongoConfig extends AbstractMongoClientConfiguration { @Override protected String getDatabaseName() { return "test"; } @Override public MongoClient mongoClient() { ConnectionString connectionString = new ConnectionString("mongodb://localhost:27017/test"); MongoClientSettings mongoClientSettings = MongoClientSettings.builder() .applyConnectionString(connectionString) .build(); return MongoClients.create(mongoClientSettings); } @Override public Collection getMappingBasePackages() { return Collections.singleton("com.baeldung"); } }

Remarque: nous n'avons pas eu besoin de définir le bean MongoTemplate dans la configuration précédente car il est déjà défini dans AbstractMongoClientConfiguration.

Nous pouvons également utiliser notre configuration à partir de zéro sans étendre AbstractMongoClientConfiguration - comme suit:

@Configuration public class SimpleMongoConfig { @Bean public MongoClient mongo() { ConnectionString connectionString = new ConnectionString("mongodb://localhost:27017/test"); MongoClientSettings mongoClientSettings = MongoClientSettings.builder() .applyConnectionString(connectionString) .build(); return MongoClients.create(mongoClientSettings); } @Bean public MongoTemplate mongoTemplate() throws Exception { return new MongoTemplate(mongo(), "test"); } }

4. Configuration pour MongoRepository

4.1. Configuration XML

Pour utiliser des référentiels personnalisés (étendant le MongoRepository ) - nous devons continuer la configuration à partir de la section 3.1 et configurer les référentiels:

4.2. Configuration Java

De même, nous allons construire sur la configuration que nous avons déjà créée dans la section 3.2 et ajouter une nouvelle annotation dans le mix:

@EnableMongoRepositories(basePackages = "com.baeldung.repository") 

4.3. Créer le référentiel

Maintenant, après la configuration, nous devons créer un référentiel - étendant l' interface MongoRepository existante :

public interface UserRepository extends MongoRepository { // }

Nous pouvons maintenant câbler automatiquement ce UserRepository et utiliser les opérations de MongoRepository ou ajouter des opérations personnalisées.

5. Utilisation de MongoTemplate

5.1. Insérer

Commençons par l'opération d'insertion; commençons également avec une base de données vide:

{ }

Maintenant, si nous insérons un nouvel utilisateur:

User user = new User(); user.setName("Jon"); mongoTemplate.insert(user, "user");

La base de données ressemblera à ceci:

{ "_id" : ObjectId("55b4fda5830b550a8c2ca25a"), "_class" : "com.baeldung.model.User", "name" : "Jon" }

5.2. Enregistrer - Insérer

The save operation has save-or-update semantics: if an id is present, it performs an update, if not – it does an insert.

Let's look at the first semantic – the insert; here's the initial state of the database:

{ }

When we now save a new user:

User user = new User(); user.setName("Albert"); mongoTemplate.save(user, "user");

The entity will be inserted in the database:

{ "_id" : ObjectId("55b52bb7830b8c9b544b6ad5"), "_class" : "com.baeldung.model.User", "name" : "Albert" }

Next, we'll look at the same operation – save – with update semantics.

5.3. Save – Update

Let's now look at save with update semantics, operating on an existing entity:

{ "_id" : ObjectId("55b52bb7830b8c9b544b6ad5"), "_class" : "com.baeldung.model.User", "name" : "Jack" }

Now, when we save the existing user – we will update it:

user = mongoTemplate.findOne( Query.query(Criteria.where("name").is("Jack")), User.class); user.setName("Jim"); mongoTemplate.save(user, "user");

The database will look like this:

{ "_id" : ObjectId("55b52bb7830b8c9b544b6ad5"), "_class" : "com.baeldung.model.User", "name" : "Jim" }

As you can see, in this particular example, save uses the semantics of update, because we use an object with given _id.

5.4. UpdateFirst

updateFirst updates the very first document that matches the query.

Let's start with the initial state of the database:

[ { "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Alex" }, { "_id" : ObjectId("55b5ffa5511fee0e45ed614c"), "_class" : "com.baeldung.model.User", "name" : "Alex" } ]

When we now run the updateFirst:

Query query = new Query(); query.addCriteria(Criteria.where("name").is("Alex")); Update update = new Update(); update.set("name", "James"); mongoTemplate.updateFirst(query, update, User.class);

Only the first entry will be updated:

[ { "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "James" }, { "_id" : ObjectId("55b5ffa5511fee0e45ed614c"), "_class" : "com.baeldung.model.User", "name" : "Alex" } ]

5.5. UpdateMulti

UpdateMultiupdates all document that matches the given query.

First – here's the state of the database before doing the updateMulti:

[ { "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Eugen" }, { "_id" : ObjectId("55b5ffa5511fee0e45ed614c"), "_class" : "com.baeldung.model.User", "name" : "Eugen" } ] 

Now, let's now run the updateMulti operation:

Query query = new Query(); query.addCriteria(Criteria.where("name").is("Eugen")); Update update = new Update(); update.set("name", "Victor"); mongoTemplate.updateMulti(query, update, User.class);

Both existing objects will be updated in the database:

[ { "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Victor" }, { "_id" : ObjectId("55b5ffa5511fee0e45ed614c"), "_class" : "com.baeldung.model.User", "name" : "Victor" } ]

5.6. FindAndModify

This operation works like updateMulti, but it returns the object before it was modified.

First – the state of the database before calling findAndModify:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Markus" } 

Let's look at the actual operation code:

Query query = new Query(); query.addCriteria(Criteria.where("name").is("Markus")); Update update = new Update(); update.set("name", "Nick"); User user = mongoTemplate.findAndModify(query, update, User.class);

The returned user object has the same values as the initial state in the database.

However, the new state in the database is:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Nick" }

5.7. Upsert

The upsert works operate on the find and modify else create semantics: if the document is matched, update it, else create a new document by combining the query and update object.

Let's start with the initial state of the database:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Markus" }

Now – let's run the upsert:

Query query = new Query(); query.addCriteria(Criteria.where("name").is("Markus")); Update update = new Update(); update.set("name", "Nick"); mongoTemplate.upsert(query, update, User.class);

Here's the state of the database after the operation:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Nick" }

5.8. Remove

The state of the database before calling remove:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Benn" }

Let's now run remove:

mongoTemplate.remove(user, "user");

The result will be as expected:

{ }

6. Using MongoRepository

6.1. Insert

First – the state of the database before running the insert:

{ }

Now, when we insert a new user:

User user = new User(); user.setName("Jon"); userRepository.insert(user); 

Here's the end state of the database:

{ "_id" : ObjectId("55b4fda5830b550a8c2ca25a"), "_class" : "com.baeldung.model.User", "name" : "Jon" }

Note how the operation works the same as the insert in the MongoTemplate API.

6.2. Save Insert

Similarly – save works the same as the save operation in the MongoTemplate API.

Let's start by looking at the insert semantics of the operation; here's the initial state of the database:

{ }

Now – we execute the save operation:

User user = new User(); user.setName("Aaron"); userRepository.save(user);

This results in the user being added to the database:

{ "_id" : ObjectId("55b52bb7830b8c9b544b6ad5"), "_class" : "com.baeldung.model.User", "name" : "Aaron" }

Note again how, in this example, save works with insert semantics, because we are inserting a new object.

6.3. Save Update

Let's now look at the same operation but with update semantics.

First – here's the state of the database before running the new save:

{ "_id" : ObjectId("55b52bb7830b8c9b544b6ad5"), "_class" : "com.baeldung.model.User", "name" : "Jack"81*6 }

Now – we execute the operation:

user = mongoTemplate.findOne( Query.query(Criteria.where("name").is("Jack")), User.class); user.setName("Jim"); userRepository.save(user);

Finally, here is the state of the database:

{ "_id" : ObjectId("55b52bb7830b8c9b544b6ad5"), "_class" : "com.baeldung.model.User", "name" : "Jim" }

Note again how, in this example, save works with update semantics, because we are using an existing object.

6.4. Delete

The state of the database before calling delete:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Benn" }

Let's run delete:

userRepository.delete(user); 

The result will simply be:

{ }

6.5. FindOne

The state of the database when findOne is called:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Chris" }

Let's now execute the findOne:

userRepository.findOne(user.getId()) 

The result which will return the existing data:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Chris" }

6.6. Exists

The state of the database before calling exists:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Harris" }

Now, let's run exists:

boolean isExists = userRepository.exists(user.getId());

Which of course will return true.

6.7. FindAll W ith Sort

The state of the database before calling findAll:

[ { "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Brendan" }, { "_id" : ObjectId("67b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Adam" } ]

Let's now run findAll with Sort:

List users = userRepository.findAll(Sort.by(Sort.Direction.ASC, "name"));

The result will be sorted by name in ascending order:

[ { "_id" : ObjectId("67b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Adam" }, { "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Brendan" } ]

6.8. FindAll W ith Pageable

The state of the database before calling findAll:

[ { "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Brendan" }, { "_id" : ObjectId("67b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Adam" } ]

Let's now execute findAll with a pagination request:

Pageable pageableRequest = PageRequest.of(0, 1); Page page = userRepository.findAll(pageableRequest); List users = pages.getContent();

The resulting users list will be only one user:

{ "_id" : ObjectId("55b5ffa5511fee0e45ed614b"), "_class" : "com.baeldung.model.User", "name" : "Brendan" }

7. Annotations

Finally, let's also go over the simple annotations that Spring Data uses to drive these API operations.

@Id private String id;

The field level @Id annotation can decorate any type, including long and string.

If the value of the @Id field is not null, it's stored in the database as-is; otherwise, the converter will assume you want to store an ObjectId in the database (either ObjectId, String or BigInteger work).

Next – @Document:

@Document public class User { // }

This annotation simply marks a class as being a domain object that needs to be persisted to the database, along with allowing us to choose the name of the collection to be used.

8. Conclusion

This article was a quick but comprehensive introduction to using MongoDB with Spring Data, both via the MongoTemplate API as well as making use of MongoRepository.

The implementation of all these examples and code snippets can be found over on Github.