Entity database persistence

To persist an entity, for example Policy entity (insurance domain):

    public class Policy : Entity, IAggregateRoot
    {
    }

into a database, follow these steps:

1. Add CoreDdd.Nhibernate package into the project.
2. Create a new NHibernate configurator class derived from NhibernateConfigurator to configure NHibernate and to let it know where to look for entities for persistence:

    public class CoreDddSampleNhibernateConfigurator : NhibernateConfigurator
    {
        public CoreDddSampleNhibernateConfigurator()
            : base(mapDtoAssembly: false)
        {
        }

        protected override Assembly[] GetAssembliesToMap(bool mapDtoAssembly)
        {
            return new[] { typeof(Policy).Assembly };
        }
    }

3. Add a new file hibernate.cfg.xml into the solution to configure which database to persist the entities into. SQLite example:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
  <session-factory>

    <property name="connection.connection_string">Data Source=CoreDddSampleConsoleApp.db</property>
    <property name="dialect">NHibernate.Dialect.SQLiteDialect</property>
    <property name="connection.driver_class">NHibernate.Driver.SQLite20Driver</property>
    <property name="connection.release_mode">on_close</property>

    <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
    <property name="show_sql">false</property>
    <property name="proxyfactory.factory_class">NHibernate.Bytecode.DefaultProxyFactoryFactory, NHibernate</property>
    <property name="transaction.use_connection_on_system_prepare">false</property>

  </session-factory>
</hibernate-configuration>

SQL server example:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
  <session-factory>

    <property name="connection.connection_string">Server=<server name>; User=<user name>;Password=<password>;Initial Catalog=CoreDddSampleConsoleApp;</property>
    <property name="dialect">NHibernate.Dialect.MsSql2008Dialect</property>
    <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>

    <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
    <property name="show_sql">false</property>
    <property name="proxyfactory.factory_class">NHibernate.Bytecode.DefaultProxyFactoryFactory, NHibernate</property>
    <property name="transaction.use_connection_on_system_prepare">false</property>

  </session-factory>
</hibernate-configuration>

PostgreSQL example:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
  <session-factory>

    <property name="connection.connection_string">Server=<server name>;Port=5432;Database=CoreDddSampleConsoleApp;User Id=<user name>;Password=<password>;Enlist=true</property>
    <property name="dialect">NHibernate.Dialect.PostgreSQL82Dialect</property>
    <property name="connection.driver_class">NHibernate.Driver.NpgsqlDriver</property>

    <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
    <property name="show_sql">false</property>
    <property name="proxyfactory.factory_class">NHibernate.Bytecode.DefaultProxyFactoryFactory, NHibernate</property>
    <property name="transaction.use_connection_on_system_prepare">false</property>

  </session-factory>
</hibernate-configuration>

In hibernate.cfg.xml properties, set 'Build Action' to 'Content' and 'Copy to Output Directory' to 'Copy if newer' - this will copy hibernate.cfg.xml into the build output folder (e.g. bin\Debug\netcoreapp2.1).

4. Add your data provider package into the project, e.g. System.Data.SQLite.Core for SQLite, System.Data.SqlClient for SQL Server, Npgsql for PostgreSQL.

5. Add a method to create a database, SQLite example:

        private static void _CreateDatabase(INhibernateConfigurator nhibernateConfigurator)
        {
            var configuration = nhibernateConfigurator.GetConfiguration();
            var connectionString = configuration.Properties["connection.connection_string"];

            using (var connection = new SQLiteConnection(connectionString))
            {
                connection.Open();
                new SchemaExport(configuration).Execute(
                        useStdOut: true,
                        execute: true,
                        justDrop: false,
                        connection: connection,
                        exportOutput: Console.Out)
                    ;
            }
        }

You can replace SQLiteConnection by SqlConnection for SQL Server or NpgsqlConnection for PostgreSQL.

6. Persist a Policy entity using the following code:

            var nhibernateConfigurator = new CoreDddSampleNhibernateConfigurator();
            _CreateDatabase(nhibernateConfigurator);

            using (var unitOfWork = new NhibernateUnitOfWork(nhibernateConfigurator))
            {
                unitOfWork.BeginTransaction();

                var policyRepository = new NhibernateRepository<Policy>(unitOfWork);

                try
                {
                    var policy = new Policy();

                    policyRepository.Save(policy);

                    unitOfWork.Commit();
                }
                catch
                {
                    unitOfWork.Rollback();
                    throw;
                }
            }

The entity persistence sample above is available here as .NET Core console app.