Question

I have created a custom Model Binder that inherits from DefaultModelBinder, and overriding the BindProperty method to set the “duration” property to 35.

protected override void BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor)
    {
        if (propertyDescriptor.Name == "Duration")
        {
            var request = controllerContext.HttpContext.Request;
            var prefix = propertyDescriptor.Name;

            SetProperty(controllerContext, bindingContext, propertyDescriptor, 35);
        }
        base.BindProperty(controllerContext, bindingContext, propertyDescriptor);
    }

A breakpoint in this method gets hit, and all seems well, But when my action is hit after, my model has reverted back to giving Duration is default value of 0.

[HttpPost]
public ActionResult Create(ModelType model)
    { var val = model.Duration;
      //val = 0 :(
    }

I’m a little stuck, please help.

Answer 1

That’s because you are calling the base method. Try like this:

protected override void BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor)
{
    if (propertyDescriptor.Name == "Duration")
    {
        var request = controllerContext.HttpContext.Request;
        var prefix = propertyDescriptor.Name;

        SetProperty(controllerContext, bindingContext, propertyDescriptor, 35);
        return; // <!-- We have set the value so no need to continue any more
    }

    // This will be called for all other properties
    base.BindProperty(controllerContext, bindingContext, propertyDescriptor);
}