com.gruelbox.tools.dropwizard.guice.hibernate.HibernateBundleFactory Maven / Gradle / Ivy

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/**
 * dropwizard-guice-box
 * Copyright 2018-2019 Graham Crockford
 *
 * 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 com.gruelbox.tools.dropwizard.guice.hibernate;

import java.util.List;
import java.util.Set;
import java.util.function.Function;

import org.hibernate.SessionFactory;

import com.google.common.base.MoreObjects;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.inject.Inject;

import io.dropwizard.Configuration;
import io.dropwizard.db.DataSourceFactory;
import io.dropwizard.db.ManagedDataSource;
import io.dropwizard.db.PooledDataSourceFactory;
import io.dropwizard.hibernate.HibernateBundle;
import io.dropwizard.hibernate.SessionFactoryFactory;
import io.dropwizard.setup.Environment;

/**
 * Constructs a {@link HibernateBundle}, deferring provision of injected
 * resources such as {@link EntityContribution} until after injection.
 *
 * @author Graham Crockford
 *
 * @param  The DropWizard configuration type in use in the application.
 */
public class HibernateBundleFactory {

  @Inject private Set additionalEntities;
  private final Function configurator;
  private HibernateBundle bundle;

  /**
   * Constructor. Initialise with a lambda which will provide an
   * appropriately configured {@link DataSourceFactory} from the
   * application configuration.
   *
   * @param configurator Returns a configured {@link DataSourceFactory}.
   */
  public HibernateBundleFactory(Function configurator) {
    this.configurator = configurator;
  }

  /**
   * Constructs the deferred-initialisation {@link HibernateBundle} on
   * first request, then returns the same instance each time.
   *
   * @return The bundle.
   */
  public HibernateBundle bundle() {
    return MoreObjects.firstNonNull(bundle, create());
  }

  private HibernateBundle create() {

    // Defer collecting the entity list until after the creation of the injector
    // since otherwise the Application would have to know about all the entities
    // in use throughout the application.
    SessionFactoryFactory sessionFactoryFactory = new SessionFactoryFactory() {
      @Override
      public SessionFactory build(HibernateBundle bundle,
          Environment environment,
          PooledDataSourceFactory dbConfig,
          ManagedDataSource dataSource,
          List> entities) {
        return super.build(
          bundle, environment, dbConfig, dataSource,
          FluentIterable.concat(entities, FluentIterable.from(additionalEntities).transformAndConcat(EntityContribution::getEntities)).toList()
        );
      }
    };

    // Construct the bundle, without excessive knowledge of the application
    // configuration
    bundle = new HibernateBundle(ImmutableList.of(), sessionFactoryFactory) {
      @Override
      public DataSourceFactory getDataSourceFactory(T configuration) {
        return configurator.apply(configuration);
      }
    };

    return bundle;
  }
}