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POMVC: Invoking overloaded constructors conditionally
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  1. POMVC: Invoking overloaded constructors conditionally
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    copied!<p>I have an MVC application where I am implementing CQRS where I have seperated saving data from reading data into seperate interfaces. I am using constructor injection for injecting the concrete instances of these interfaces into the Controller. For constructor injection I am using Unity container. See below example</p> <pre class="lang-cs prettyprint-override"><code>//The Employee controller public class EmployeeController : Controller { IEmployeeRepository _Writer; IEmployeeQuery _Reader; //constructor injection public EmployeeController(IEmployeeRepository writer, IEmployeeQuery reader) { this._Writer = writer; this._Reader = reader; } //To Do: constructor injection for write operations only public EmployeeController(IEmployeeRepository writer) { this._Writer = writer; } //To Do: constructor injection for read operations only public EmployeeController(IEmployeeQuery reader) { this._Reader = reader; } } //Registration of the concrete types in the unity container. public static class Bootstrapper { public static void ConfigureUnityContainer() { IUnityContainer container = new UnityContainer(); container.RegisterType&lt;IEmployeeRepository, EmployeeRepository&gt;(new HttpContextLifetimeManager&lt;IEmployeeRepository&gt;()); container.RegisterType&lt;IEmployeeQuery, EmployeeQueries&gt;(new HttpContextLifetimeManager&lt;IEmployeeQuery&gt;()); ControllerBuilder.Current.SetControllerFactory(new UnityControllerFactory(container)); } } //The derived Controller Factory for injection dependencies in the Controller constructor public class UnityControllerFactory : DefaultControllerFactory { IUnityContainer container; public UnityControllerFactory(IUnityContainer container) { this.container = container; } protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType) { try { if (controllerType == null) { throw new ArgumentNullException("controllerType"); } if (!typeof(IController).IsAssignableFrom(controllerType)) { throw new ArgumentException(String.Format("Type requested is not a controller: {0}", controllerType.Name), "controllerType"); } return container.Resolve(controllerType) as IController; } catch (Exception) { return null; } } } </code></pre> <p>I have figured out that for any action I will either be fetching data or writing data but not both. In that case I need to invoke the controller constructors conditionally depending on which of "_Writer" or "_Reader" I need to initialize. </p> <p>How can this be done ?</p>
 

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