How do I return a Json object from Action Attribute?

Question

when overriding OnActionExecuting, how do I return a Json result without passing to action?

Answer 1

I find it useful to use Json.NET to generate the json output. This has many advantages, for example JSON properties can be hidden under certain conditions.

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
    if (/* whatever */)
    {
        var result = new ResultModel(); // your json model
        ContentResult content = new ContentResult();
        content.ContentType = "application/json";
        content.Content = JsonConvert.SerializeObject(result);
        filterContext.Result = content;
        base.OnActionExecuting(filterContext);
    }
}