Differences between MVC and View First approach in web development - model-view-controller

Today when I searched on the internet I saw the View first approach in web development of Lift framework. Can somebody tell me the differences between view first and MVC approach ?
Thank you very much

View first is based not on a model and a controller, but mostly interested in the view. Many problem domains do not neatly compose in controllers and models. Think about a ecommerce site, the shopping cart exists on all pages, but should every controller control it? Personally in MVC too much of my time is spent thinking about how to logically make the problem fit into MVC than just coding. View first takes away this controller / view / model and instead just has a view which in Lift can call "snippets". It is almost a superset of MVC since if you wanted you could only have a single snippet per page, but Lift allows you to do much more. Snippets can be cross cutting concerns or very page specfic logic.
From the lift website..
Lift is different [from MVC]. For HTML requests, Lift loads the view first and builds your page from the view. Lift also supports REST style requests for non-HTML data. (See 11 on page 1↑) “Why?” Because complex HTML pages rarely contain a dominant piece of logic... a single controller... but contain many different components. Some of those components interact and some do not. In Lift, you define the collection of components to be rendered in the resulting HTML page in the view.

When your using lift, you basically have a view(page) and from this you could incorporate any snippet(app) that you have without much of the antics you'd normally have to do in an MVC framework/environment.
Basically you don't have to choose what the most important thing on the page is just what you want to add to a page and then add it.

Related

Spring Views - Combining elements into views

Currently, in our deployment we have a abstract type Component which represents a part of our Page, basically an element such as a Question, which can have multiple choice, a text box or any other form of answering it, or a Video that users can play, basically a shard of a page that is interchangeable, basically, our design was to have a specific area in our website which would be rendered through a list of Components, we tried at first to have each "Page" object have a List of Components, and each Component would have a method render that would return a Spring View, we thought we could iterate over the list and somehow mash the views together.
We also tried using XSTLViews with no more success, it seems to be more of a design problem and our abuse of the way Spring MVC should be used.
We will really be glad to receive any advice/tips/corrections about how to do it right and maybe some corrections about misconceptions we might have.
It sounds like you're more than half way to a design that uses AJAX to build your page. You're trying to mash up a bunch of Components into one request. What if you returned a container page which then requested/inserted a block of html for each URL it was given a render time. Each of these URLs would refer to a single component. It might be a performance hit if you are including a lot of these Components, but it seems to fit the design.

Zend framework Nesting controllers

Zend framework Nesting controllers
I was wonder if it is possible to have nested controllers.
I have an application that has a page with left bar and right bar.
| --TAB----TAB----TAB--
MyGroups |
|
So I want to have one controller to be as a wrapper for entire page
then have myGroups controller for left bar, and for right side, there are many tabs that would show based on some selections.
So I want to have one controller for each tab.
This is a very big application and each of those tabs do lots of other things.
So I want have separate controller/model/view/layout for each tab and also for left side's myGroups.
What is the best way to approach this.
I appreciate if you give me some code structure too.
Thank you very much.
Alex
You could use the the Action view-helper in your layout for each or your left and right bars. But the downside to this is that you incur three full server calls (complete with bootstrap and dispatch cycle) to render a single page. I consider that to be a pretty significant downside, especially if each bar needs its own database connection.
An alternative approach is to use front-controller plugins for your left and right bars. Register them at bootstrap, give them a postDispatch() hook which accesses/generates whatever data they need and places that data into the layout/view. Then your layout renders the content without needing to know how it got there.
If you use the 'action view-helper' suggested by David, you could always ajax these in for better UX - therefore the user can read what has currently been loaded, while waiting for the rest of the page.

MVC3, custom object lists and searching

I'm new to MVC3 (and MVC in general) and looking for a bit of advice. Pointing me in the direction of some good articles or tutorials would be good enough I think. I'm a bit familiar with the concept of MVC, and I've been a c# programmer (hobbyist and partly professional) for a while now.
The issue I have is that I have an object (call it "Game"), which has a List<T> as a property (call T "Player"), and I want the user to "select" the player to add them to the Game.
All players would be managed in another part of the application, so there is no need to think about "managing" the master player pool at this point.
I'm looking for a best practice for:
adding custom objects to a list that of n length while on a page.
Searching for and selecting a custom object in the first place.
I can do the standard pages for the database access so that's not a problem. In asp I would have just done something like a wizard and managed everything through postback on the page, but I want to try and keep to best practice where i can for this project.
Any pointers welcome, also looking for some good physical books to buy on MVC.
If I understand you correctly you want two elements within the page, a player search (over all players) and a list of players already added to the game.
For the player search you want to use a bit of jQuery to hook up an actionResult that returns a JSON result of your player results. You can then display these results without having to leave the page, in appearance much like an AJAX post in webforms.
You have more options for how you add the player to the game, depending on if you want to add more than one at once, or want a backout stage (so you can "add" players and then cancel out and they won't be added).
the option I think would give the most seamless interface would be a jQuery/javascript call to an action method which datawise adds your player to the game, and use jQuery to add the element to your players in the game on the page.
For the adding of a player in your controller you could return a bool in a JSON result, just you have confirmation that the player was successfully added to the list.
For reference: This is quite an old article but highlights the power of working with jQuery and MVC quite nicely I think http://andreasohlund.net/2008/12/21/asp-net-mvc-jquery-true/

CodeIgniter - big site best practices

CodeIgniter + Template howto design a portal like behavior.
I'm not getting the concept of how to design bigger sites with CodeIgniter and Templates.
The templates I'm using is Template Library for CodeIgniter. I'm having problems solving the following.
What I can see I need is some MasterTemplate that provides "MainRegion" for ProductCatalogue browsing and Account management etc. Then I would like to have a concept of "Widgets" loaded from the MasterTemplate that the user does not interact directly with instead it is simply informative. Ex: ShoppingCartWidget, TopNews etc...
Example of problems:
A) Widget - A shopping cart widget exposes a minimalistic resume of what user has added when browsing the the product catalog in the "MainRegion".
B) Hierachival view structure - When navigating to the "Account section" of the site the site renders a sub-view of the account system in the "MainRegion". My problem is that the state of the AccountSection is lost when I for example leave the "AccountSection" in to "ProductCatalogue" and the back to "Accountsection". I want to be able to render each subsection independtly smothly insterted into the "MainRegion" in the master template.
I really don't get the architecture. I need help to bring real modularity into the design.
I would like to achive the following:
1) View fragments should render from a its own model. Ex: ShoppingCartWidget always reads its state from ShoppingCartModel.
3) View fragments should have a display[on/off] in some MasterTemplate concept. So that I can Ex: Start showing the ShoppingCartWidget when there is something in the ShoppingCart. (I don't want to render '').
4) Stateful views. Ex: UserLoggedIn/UserNotLoggedIn
I'm missing the complex design principles for bigger sites or best practices for CI.
Very greatful for any help!
Thanks
Niclas
HMVC for Codeigniter does what you want: https://bitbucket.org/wiredesignz/codeigniter-modular-extensions-hmvc/wiki/Home

How to display multiple widgets on the same page using MVC

I'm a bit confused about how MVC works and I can't find anything but basic examples.
I want to make a kind of widget-based design; you can choose various widgets to go on your page. Each widget should be responsible for itself - it should have a controller and a view. But what about the main page? Suddenly I've got a page with lots of controllers on it!
The obvious thing to do is to embed the controllers in the view somehow... This is my widget {SomeWidget} but I've read that "breaks the MVC paradigm".
Some widgets will need to POST to different urls (like a search box goes to the result page) and some will need to POST back to the same URL (like adding a comment to an article brings you back to the article).
To top things off, the user should be able to edit the HTML around the widget - for example if they want a search box on the right, they can type <div style="float: right;">{SearchController}</div> (in my paradigm-breaking world)
I am not very good at web programming, but i believe, from the example you described, that there should be one model, one view and one controller for the entire page. Now the view itself should contain the views for every widget in the page (and the same goes for the page controller) to which it dispatches the messages it receives.
Conceptually there is a lower level of MVC (for widgets) and a higher level of MVC (for the page). And the MVC paradigm won't be broken. Now you can edit the HTML around the widget, it changes the page model (and not any widget model).
Hope this helps !
To add to #Benoît's comment:
The Symfony framework handles this with components. Each component is a self-contained MVC instance that can be embedded into another view. It cannot be instantiated to respond directly to web requests like the normal MVC instance (a module/action pair). It can only be embedded into another MVC view.
As a side note: Symfony also treats plugins as their own complete MVC instance, complete with its own schema, models, controllers, config files, views, et al.
In your case, each component would be its own MVC instance and the app would stitch these components together. Each component would be responsible for how it responds to a form submit.
MVC doesn't mean there is ONE view and ONE controller. It just means the app logic is stored in models, the controller glues things together, and the view builds the display. It's a formal and logical separation of logic and presentation.
One of the best, short, and simple books I have found on MVC is this one handed out last week at the PDC 2008 expo:
http://www.apress.com/book/view/1430216468
Not only does it cover MVC's concept, but its comparisons to other concepts such as Ruby on Rails and MVP methodology.
In addition, it goes into the entire reason MVC exists by describing it's seperation of concerns, and why it should not only be at the UI level - but down into your actual layers or IoC structure of your business objects and DAL.
I'd highly recommend this book as he covers best practices, in just 110 pages or so.
And no, I do not work for FirstPress or related to them at all. I just liked the book, and finally someone I agree with.
The best information I've found on doing widgets in ASP.NET MVC is on Steve Sanderson's blog. He explains his concept of partial requests which is a different technique than sub-controllers.
http://blog.codeville.net/2008/10/14/partial-requests-in-aspnet-mvc/
Partial Requests are easy You’ve heard of partial views, so how about
partial requests? Within any MVC
request, you can set up a collection
of internal partial requests, each of
which can set up its own internal
partial requests and so on. Each
partial request renders a plain old
action method in any of your plain
regular controllers, and each can
produce an independent widget. I’m
calling them partial “requests” rather
than “controllers” because they run a
proper MVC request-handling pipeline
that’s compatible with your routing
system and your controller factory.
Still, as with subcontrollers, all the
control remains in controllers, and
the view can be ignorant.
There are a lot of variations on the MVC theme and a lot to consider before coming to a conclusion as to the design of your particular system. Most of the latest, popular web based systems look to IoC as the guiding principal. Usually, some kind of framework component is the controller that uses some kind of configuration to invoke the proper template as the view and to couple it with the appropriate object hierarchy as the model. Most of these systems include an extensible GUI widget library to be used by the templates. You can add your own widgets but it is not best practice to hard code your widgets to a specific object hierarchy. That IoC link also talks about components and services which should give you some direction on how to avoid that hard coding.
ASP.NET MVC is well suited for a widget dashboard mashup type page.
Take a look at this session from PDC 2008.
You will probably want to use the Ajax helpers to update the islands of data in each widget. Here is a snippet of how you could put a calculator on any page but keep the code independent.
View Snippet:
<script type="text/javascript">
function OnFailure(error) {
alert("We have encounterd an error " + error);
}
</script>
<% using (Ajax.BeginForm("Add", new AjaxOptions{UpdateTargetId="sum", OnFailure="OnFailure"})){ %>
<%= Html.TextBox("x") %> +
<%= Html.TextBox("y") %> =
<span id="sum">?</span>
<input type="submit" value="AddEm" />
<% } %>
Controller Snippet:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Add(string x, string y)
{
int sum = int.Parse(x) + int.Parse(y);
return Content(sum.ToString());
}
I think JarrettV's and jcoby's answers are closest.
I've come to know subcontrollers as Hierarchical MCV (HMVC). The idea is that you "pull" content (a view populated by a subcontroller) from the parent view template instead of "pushing" data to the template from the controller. So instead of needing to edit both the controller and view to add a widget, you just call the widget from the view. There are libraries to accomplish this in the php frameworks CodeIgniter (Modular Extensions) and Kohana (Dispatch, and Component).

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