Why Using JSON in MVC application?

Question

First i would like to apologize if this is a stupid question. While learning MVC i came a cross creating a strong type views based on model which for example will display all Users by 2 different functions, first will return a View passing a collection of users second will return a collection of JSON objects. so my question is, as i'm not familiar with JSON and for me using Models are more clear, why then using JSON in MVC?

In short why using:

var users = _db.Users
           .Where(r => r.Name.Contains(q))
           .Take(10)
           .Select(r => new { r.Name,r.LastName,r.Address.Country });
        return Json(users, JsonRequestBehavior.AllowGet);

In place of:

 var users= _db.Users
           .Where(r => r.Name.Contains(q))
           .Take(10);
            return View(users);

Maybe this is a bad code example, but why converting Models to Jason before passing them to a view, if we can directly pass the models.

Answer 1

For the first code snippet, it is more likely that it is used for a ajax call to seamlessly load the data from the server to the client and perhaps keep refreshing it without reloading the page. Also, the Users entity may have much more information than needed by the client, so the first example is reducing the information served and doesn't require you to create a new model to represent it.

The second example would be a controller action actually returning a view and that view is strongly typed.

If you would make a project that uses the WebApi, you wouldn't return views, you would expect the client to ask for data and that the client renders it how it sees fit.