Troller — the trollful way of working with asp.net MVC

This is an approach called variously 'troller', 'beCool' or WTFLeon?. A more accurate name would be "AjaxAwareController".

It's been a while since I used this approach, but I want to document it for posterity and so that I can do something similarly awful to other frameworks in the future.

I was working with asp.net MVC a fair bit, back in 2013 and sometimes I wanted to return JSON from methods, sometimes (often) I wanted that JSON to contain rendered html, because javascript templating was not up to scratch (then and now).

Hence I created a class, Troller, that derived from Controller (and you must know how loathe i am to inherit... the only thing worse than inheritance hierarchies are database transactions: ideas that are universally overused)

namespace System.Web.Mvc
{
    using System;

    public class Troller : Controller
    {
        public ActionResult Partial(bool successValue, Object model)
        {
            if (this.Request.IsAjaxRequest())
            {
                return this.Json(new { success = successValue, html = this.RenderPartialViewToString(model) });
            }
            else
            {
                return PartialView(model);
            }
        }

        public ActionResult Partial(bool successValue, string viewName, Object model, JsonRequestBehavior jrq)
        {
            if (this.Request.IsAjaxRequest())
            {
                return this.Json(new { success = successValue, html = this.RenderPartialViewToString(viewName, model) }, jrq);
            }
            else
            {
                return PartialView(viewName, model);
            }
        }

        public ActionResult Partial(bool successValue, Object model, JsonRequestBehavior jrq)
        {
            if (this.Request.IsAjaxRequest())
            {
                return this.Json(new { success = successValue, html = this.RenderPartialViewToString(model) }, jrq);
            }
            else
            {
                return PartialView(model);
            }
        }

        public ActionResult Redirect(bool successValue, string redirectUrl)
        {
            if (this.Request.IsAjaxRequest())
            {
                return this.Json(new { success = successValue, redirectTo = redirectUrl });
            }
            else
            {
                return Redirect(redirectUrl);
            }
        }
    }
}

All of that relies heavily on the ability to renderPartialViewToString — which comes from these extension methods (3 overloads and an actual — still wish there was an attribute for "actual!" ) :

namespace System.Web.Mvc
{
    using System.IO;

    public static class ControllerExtensions
    {

        public static string RenderPartialViewToString(this Controller controller)
        {
            return controller.RenderPartialViewToString((string)null, null);
        }

        public static string RenderPartialViewToString(this Controller controller, object model)
        {
            return controller.RenderPartialViewToString(null, model);
        }

        public static string RenderPartialViewToString(this Controller controller, string viewName)
        {
            return controller.RenderPartialViewToString(viewName, null);
        }

        public static string RenderPartialViewToString(this Controller controller, string viewName, object model)
        {
            if (string.IsNullOrEmpty(viewName))
                viewName = controller.ControllerContext.RouteData.GetRequiredString("action");

            controller.ViewData.Model = model;

            using (var sw = new StringWriter())
            {
                var viewResult = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName);
                var viewContext = new ViewContext(controller.ControllerContext, viewResult.View, controller.ViewData, controller.TempData, sw);
                viewResult.View.Render(viewContext, sw);

                return sw.GetStringBuilder().ToString();
            }
        }
    }
}

Then, each Controller would inherit from Troller (instead of inheriting from Controller) — and would be able to, for example:

    return this.Partial(true, model);

(note my loathing of inheritance... i was willing to accept the user deleting 'con' from the start of an inheritance hierarchy they were already forced to accept, but not willing to accept them inheriting from AjaxAwareController or anything like that...)

Thereafter, if the route had been requested by a normal click: no problems, it all happened the same, but if it had been requested via AJAX, the result would be wrapped in JSON containing .success = true (or false) and the accompanying html in a .html property. And it therefore relied on the client-side javascript expecting such a result.

Here's the javascript describing ALL form submissions... And it depends on the following assumptions:

  1. The form submission should be performed over ajax, not via a regular form submission
  2. The target of the form submit comes from form[0].action
  3. Any item within the form being submitted that has a class of progress should be given a class of waiting.
  4. The nearest parent of the form, classed either modal or span10 should be replaced with the result of this submission.
  5. A complete description of the form being submitted can be obtained from the ToJson(form) method (described below)
  6. Whatever result comes back, it should have the same rules applied to it, as the entire document did upon ready (via a function called beCool)
here.find('form').submit(function (e) {
    var form, url, action;
    form = $(this);
    url = form[0].action;
    data = toJson(form);
    element = form.closest(".modal,.span10");
    form.find('.progress').addClass('waiting');

    postElement(url, data, element, function (result) {
        if (result.redirectTo) {
            window.location = result.redirectTo;
        }
        if (result.html) {
            element.html(result.html);
            beCool(element);
        } else {
            if (result.success == false) {
                notCool(result.message);
            }
            //what if no result.html and: result.success = true, or no result.success?
        }
    });
    e.preventDefault();
    return false;
});

The postElement method, alluded to above, is as follows:

function postElement(url, data, element, successAction) {
    if (successAction == undefined) {
        successAction = function (result) {
            var html = result.html || result;
            $(element).html(html);
            beCool(element);
        };
    }

    data = JSON.stringify(data);

    $.ajax({
        url: url,
        type: 'POST',
        data: data,
        cache: false,
        contentType: "application/json; charset=utf-8",
        success: successAction,
        beforeSend: function () {
            $(element).addClass('waiting');
        },
        complete: function () {
            $(element).removeClass('waiting');
        },
        error: handleError
    });
}

And the toJson which is kind of asp.net MVC specific, as described in the comments:

function toJson(form) {
    // find inputs
    var inputs = $(form).find(':input');
    var values = {};
    inputs.each(function () {
        if (!this.name) return; //unnamed inputs are typically submit buttons

        // for radio buttons and checkboxen return their jquery checked state
        if (this.type == "radio" || this.type == "checkbox") {
            values[this.name] = $(this).is(':checked');
        } else {
            //for all other inputs (buttons, textboxes, select and textareas, return their value
            if (values[this.name] == undefined) {
                values[this.name] = $(this).val();
            } else {
                // In mvc, checkboxes render an extraneous hidden field, containing 'false', that should be ignored.
                // so, if we've already gathered a value for this control (and it was true or false) then don't read this one in
                if (!this.type == "hidden" || (!values[this.name] == true && !values[this.name] == false)) {
                    values[this.name] = $(this).val();
                }
            }
        }
    });

    return values;
}

One other thing I haven't mentioned, the accompanying CSS, implied by the assumptions above:

.progress.waiting
{
    background-image: url(/content/images/spinner.gif);
    background-repeat: no-repeat;
}

And here's some other CSS I've dug up which I applied to the progress class.

.modal-footer .progress
{
    float: right;
}

.progress
{
    margin-top: 7px;
    display: inline-block;
    width: 16px;
    height: 16px;
}

The document.ready is just a call to beCool, like this:

$(document).ready(function () {
    beCool();
});

Where 'beCool' starts like this and defines everything else about any element that is ready.

function beCool(here) {
    here = here || document;
    here = $(here);
    ...
}

results matching ""

    No results matching ""