Unity Application Block – Loading configuration information

The Unity Application Block does not automatically read the configuration information or create and prepare containers. You must programmatically instantiate a Unity container in your application. You can programmatically configure it with registrations, type mappings, and any extensions or you can configure it by reading configuration information from a file.

The following example code demonstrates how to configure unity container and load the instances from the configuration information.

public interface IRepository

{

    void Insert(T instance);

    void Update(T instance);

    T GetById(Id id);

    IEnumerable GetAll();

    bool Delete(Id id);

}

The IRepository interface is defined in the assembly UnitySamples.Infrastructure. The implementation is defined in the assembly UnitySamples.DataAccessLayer in the class EmployeeRepository

public class EmployeeRepository : IRepository<Employee, Guid>

{

    public EmployeeRepository()

    {

        ___EmployeeCollection = EmployeeFactory.Create();

    }

    public void Insert(Employee instance)

    {

        ___EmployeeCollection.ToList().Add(instance);

    }

    public void Update(Employee instance)

    {

        var __Employee = GetById(instance.Id);

        if (__Employee == null) return;

        __Employee.FirstName = instance.FirstName;

        __Employee.LastName = instance.LastName;

    }

    public Employee GetById(Guid id)

    {

        return ___EmployeeCollection.First<Employee>(x => x.Id == id);

    }

    public IEnumerable<Employee> GetAll()

    {

        return ___EmployeeCollection;

    }

    public bool Delete(Guid id)

    {

        var __Count = ___EmployeeCollection.ToList().RemoveAll(x => x.Id == id);

        return __Count > 0;

    }

    static IEnumerable<Employee> ___EmployeeCollection;

}

My application configuration file looks like

<configuration>

  <configSections>

    <section name="unity"

             type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,

                   Microsoft.Practices.Unity.Configuration,

                   Version=1.2.0.0,

                   Culture=neutral,

                   PublicKeyToken=31bf3856ad364e35" />

  configSections>

  <unity>

    <typeAliases>

     

      <typeAlias alias="singleton" type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager, Microsoft.Practices.Unity" />

     

      <typeAlias alias="IRepository`2" type="UnitySamples.Infrastructure.Interfaces.IRepository`2, UnitySamples.Infrastructure" />

      <typeAlias alias="employeeRepository" type="UnitySamples.DataAccessLayer.EmployeeRepository, UnitySamples.DataAccessLayer" />

    typeAliases>

    <containers>

      <container name="unityContainer">

        <types>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           

          <type type="IRepository`2"

                mapTo="employeeRepository"

                name="EmployeeRepository">

            <lifetime type="singleton" />

          type>

        types>       

      container>

    containers>

  unity>

configuration>

As you can see I have mentioned the IRepository interface preceeding with a ‘`’ and 2. The .NET Framework convention for expressing generic types is ObjectWithOneType`1, where the digit following the "`" matches the number of types contained in the generic type.

To load the configuration information, I have my code as

IUnityContainer __Container = new UnityContainer();

UnityConfigurationSection __Section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");

Assert.IsNotNull(__Section, "Failed to load unity section from configuration");

__Section.Containers["unityContainer"].Configure(__Container);

var __EmployeeRepository = __Container.Resolve<IRepository<Employee, Guid>>("EmployeeRepository");

Assert.IsNotNull(__EmployeeRepository, "Failed to load the repository instance from the configuration file mapping");

var __EmployeeCollection = __EmployeeRepository.GetAll();

Assert.IsNotNull(__EmployeeCollection, "Repository failed to retrieve employee data");

Assert.IsTrue(__EmployeeCollection.Count() > 0, "Repository failed to retrieve employee data");

We’ll continue looking into the details of the Unity Application block in the upcoming posts. Till then happy programming!!!.