argument for custom model binder MVC

Question

For the code below, I am wondering how Employee type affects by prefixed [] brackets

public ActionResult SaveEmployee([ModelBinder(typeof(MyEmployeeModelBinder))]Employee e, string BtnSubmit)
{
        // some logic
}

Answer 1

MyEmployeeModelBinder is a custom model binder, that will execute instead of default model binder in Employee e.

public class MyEmployeeModelBinder: DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) {
    ...
    }
}

The Employee type affects bindingContext properties in BindModel(), like bindingContext.ModelMetadata and bindingContext.ModelType, that contains information about the model. Take a look at ModelMetaData: https://msdn.microsoft.com/pt-br/library/system.web.mvc.modelmetadata%28v=vs.108%29