Validating your model before inserting into database in Asp.net MVC

We all are aware that when we take any model from view(user input) into the controller , we always tend to

use ModelState.IsValid to check if model is valid , then only we will proceed for further processing

	[HttpPost]
	[ValidateAntiForgeryToken]
	public ViewResult Share( model_document param_model_document )
	{
	// VALIDATE THE MODEL
	if(ModelState.IsValid) {
	// DO THE DESIRED TASK
	}
	return View();
	}

view raw gistfile1.cs hosted with ❤ by GitHub

But the same is not applicable when we are doing same in class file which does not inherit controller class.