Spring-data-mongodb connect to multiple databases in one Mongo instance

Question

I am using the latest spring-data-mongodb (1.1.0.M2) and the latest Mongo Driver (2.9.0-RC1). I have a situation where I have multiple clients connecting to my application a

Answer 1

You may want to sub-class SimpleMongoDbFactory and strategize how the default DB as returned by getDb is returned. One option is to use thread-local variables to decide on the Db to use, instead of using multiple MongoTemplates.

Something like this:

public class ThreadLocalDbNameMongoDbFactory extends SimpleMongoDbFactory {
    private static final ThreadLocal dbName = new ThreadLocal();
    private final String defaultName; // init in c'tor before calling super

    // omitted constructor for clarity

    public static void setDefaultNameForCurrentThread(String tlName) {
        dbName.set(tlName);
    }
    public static void clearDefaultNameForCurrentThread() {
        dbName.remove();
    }

    public DB getDb() {
        String tlName = dbName.get();
        return super.getDb(tlName != null ? tlName : defaultName);
    }
}

Then, override mongoDBFactory() in your @Configuration class that extends from AbstractMongoConfiguration like so:

@Bean
@Override
public MongoDbFactory mongoDbFactory() throws Exception {
  if (getUserCredentials() == null) {
      return new ThreadLocalDbNameMongoDbFactory(mongo(), getDatabaseName());
  } else {
      return new ThreadLocalDbNameMongoDbFactory(mongo(), getDatabaseName(), getUserCredentials());
  }
}

In your client code (maybe a ServletFilter or some such) you will need to call: ThreadLocalDBNameMongoRepository.setDefaultNameForCurrentThread() before doing any Mongo work and subsequently reset it with: ThreadLocalDBNameMongoRepository.clearDefaultNameForCurrentThread() after you are done.