Question

I have a WinForms project, which uses a lot of user controls. Some of these user controls use classes from business logic layer. These classes are mainly performing CRUD operation to a database (through data access layer) plus some additional validation and reporting.

The project uses some common objects (logged user, some controllers and validators), which are instantiated in main form and then injected into child user controls via initialization methods or public properties. This means, that I have a lot of code, which just passes these common objects from parent control to child controls.

In order to avoid this, I could create a static class (ApplicationContext for example) and save all common controls into it. This would happen in the main form and all other user controls or forms in the project could use it.

I see that this pattern is discouraged in general (storing some global data in static classes). But what if this data is immutable? Is this approach ever a good idea?

Or do you know any other approach, which could help me get rid of all the initialization code?

Answer 1

You can use an Inversion of Control container like Unity or Autofac and have it automatically wire up your object graph for you.

You can have each object that requires any one of the common objects define a dependency to their interfaces, either though a constructor argument, or as a public property, and the IoC container will wire the appropriate objects together.

Property injection example with Unity:

public class MyUserControl : UserControl 
{
    [Dependency]
    public LoggedUserService UserService { get; set; }

    public void Method()
    {
        // the IoC container will ensure that the UserService
        // property has been set to an object
    }
}

All you do in the main form is registering the common objects you want the IoC container to know about and then you ask for the root object. The object graph will be assembled magically for you and you don’t have to to all the wire code nor care how it is done.