This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Data MongoDB 4.4.1!

Configuration

You can use the following configuration to create and register an instance of MongoTemplate, as the following example shows:

Registering a MongoClient object and enabling Spring’s exception translation support

Imperative
Reactive
XML

@Configuration
class ApplicationConfiguration {

  @Bean
  MongoClient mongoClient() {
      return MongoClients.create("mongodb://localhost:27017");
  }

  @Bean
  MongoOperations mongoTemplate(MongoClient mongoClient) {
      return new MongoTemplate(mongoClient, "geospatial");
  }
}

@Configuration
class ReactiveApplicationConfiguration {

  @Bean
  MongoClient mongoClient() {
      return MongoClients.create("mongodb://localhost:27017");
  }

  @Bean
  ReactiveMongoOperations mongoTemplate(MongoClient mongoClient) {
      return new ReactiveMongoTemplate(mongoClient, "geospatial");
  }
}

<mongo:mongo-client host="localhost" port="27017" />

<bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">
  <constructor-arg ref="mongoClient" />
  <constructor-arg name="databaseName" value="geospatial" />
</bean>

There are several overloaded constructors of MongoTemplate and ReactiveMongoTemplate:

MongoTemplate(MongoClient mongo, String databaseName): Takes the MongoClient object and the default database name to operate against.
MongoTemplate(MongoDatabaseFactory mongoDbFactory): Takes a MongoDbFactory object that encapsulated the MongoClient object, database name, and username and password.
MongoTemplate(MongoDatabaseFactory mongoDbFactory, MongoConverter mongoConverter): Adds a MongoConverter to use for mapping.

Other optional properties that you might like to set when creating a MongoTemplate / ReactiveMongoTemplate are the default WriteResultCheckingPolicy, WriteConcern, ReadPreference and others listed below.

Default Read Preference

The default read preference applied to read operations if no other preference was defined via the Query.

WriteResultChecking Policy

When in development, it is handy to either log or throw an exception if the com.mongodb.WriteResult returned from any MongoDB operation contains an error. It is quite common to forget to do this during development and then end up with an application that looks like it runs successfully when, in fact, the database was not modified according to your expectations. You can set the WriteResultChecking property of MongoTemplate to one of the following values: EXCEPTION or NONE, to either throw an Exception or do nothing, respectively. The default is to use a WriteResultChecking value of NONE.

Default WriteConcern

If it has not yet been specified through the driver at a higher level (such as com.mongodb.client.MongoClient), you can set the com.mongodb.WriteConcern property that the MongoTemplate uses for write operations. If the WriteConcern property is not set, it defaults to the one set in the MongoDB driver’s DB or Collection setting.

WriteConcernResolver

For more advanced cases where you want to set different WriteConcern values on a per-operation basis (for remove, update, insert, and save operations), a strategy interface called WriteConcernResolver can be configured on MongoTemplate. Since MongoTemplate is used to persist POJOs, the WriteConcernResolver lets you create a policy that can map a specific POJO class to a WriteConcern value. The following listing shows the WriteConcernResolver interface:

public interface WriteConcernResolver {
  WriteConcern resolve(MongoAction action);
}

You can use the MongoAction argument to determine the WriteConcern value or use the value of the Template itself as a default. MongoAction contains the collection name being written to, the java.lang.Class of the POJO, the converted Document, the operation (REMOVE, UPDATE, INSERT, INSERT_LIST, or SAVE), and a few other pieces of contextual information. The following example shows two sets of classes getting different WriteConcern settings:

public class MyAppWriteConcernResolver implements WriteConcernResolver {

  @Override
  public WriteConcern resolve(MongoAction action) {
    if (action.getEntityType().getSimpleName().contains("Audit")) {
      return WriteConcern.ACKNOWLEDGED;
    } else if (action.getEntityType().getSimpleName().contains("Metadata")) {
      return WriteConcern.JOURNALED;
    }
    return action.getDefaultWriteConcern();
  }
}

Publish entity lifecycle events

The template publishes lifecycle events. In case there are no listeners present, this feature can be disabled.

@Bean
MongoOperations mongoTemplate(MongoClient mongoClient) {
    MongoTemplate template = new MongoTemplate(mongoClient, "geospatial");
	template.setEntityLifecycleEventsEnabled(false);
	// ...
}

Configure EntityCallbacks

Nest to lifecycle events the template invokes EntityCallbacks which can be (if not auto configured) set via the template API.

Imperative
Reactive

@Bean
MongoOperations mongoTemplate(MongoClient mongoClient) {
    MongoTemplate template = new MongoTemplate(mongoClient, "...");
	template.setEntityCallbacks(EntityCallbacks.create(...));
	// ...
}

@Bean
ReactiveMongoOperations mongoTemplate(MongoClient mongoClient) {
    ReactiveMongoTemplate template = new ReactiveMongoTemplate(mongoClient, "...");
	template.setEntityCallbacks(ReactiveEntityCallbacks.create(...));
	// ...
}

Document count configuration

By setting MongoTemplate#useEstimatedCount(…) to true MongoTemplate#count(…) operations, that use an empty filter query, will be delegated to estimatedCount, as long as there is no transaction active and the template is not bound to a session. Please refer to the Counting Documents section for more information.