Just to prefix this question, I've decided to take a look at moving our works old legacy systems (40+ programs from vb6, vba, vb.net to c#.net) into two separate systems using the same DAL (barcoding terminals and one web based system) as I spend most my day fixing crummy or non existant business logic in 15 year old vba programs. I've recently built an entity framework model complete with fluent validation and couldn't be happier with it after using it for a bit.
The small team is familiar with webforms (but not very) but the last few days I've explored MVC Razor. I was loving MVC Framework until I tried to start trying to add more functions onto the same page and then it seemed arbitrarily hard to replicate our a recent system I put in a webform. Before, I would eager load a customer and all it's child entities and then bind that to single page for the customer so they could access everything (which is what they wanted), it works okay and isn't slow. From this single page I could edit all their account details/contacts/emails/phones/jobs.
All the examples I've done and seen in MVC handle a single update, a single edit etc but surely you can't separate out every single action into a new view/page? I can pass a rich model through to the view in MVC, but then its a pain trying to update all the different child entities.
This is probably the exact design that MVC wasn't designed for maybe, which is okay, I'm willing to adapt it if MVC will be a better platform going forward, but how are you meant to handle adding this complexity in? Some methods I've seen:
Lots of partial views? passing child info to them (or the id and lazy loading it)?
I've seen methods that wrap multiple <forms> around everything and handle actions that way.
Separate pretty much every task out
If the solution is more lightweight and easier to maintain I'll go research whatever I need to I just wanted at an earlier stage to see if I'm wasting my time. Any pointers to the correct questions I should be asking would be greatly appreciated.
ASP.NET MVC is neither more or less better equipped to deal with complex pages than any other technology out there.
Certainly, MVC requires more low-level work than a Web Forms app, with no direct binding support, but in most cases this is a good thing and provides much more flexibility in how your page is rendered.
One of the whole ideas of MVC is to give you more control over things, but that control leads to requiring more knowledge and more effort on your part in most non-trivial cases. MVC provides a number of tooling functions to speed up trivial work (like creating standard table based CRUD) but when you have complex models, you will have to do much of the work yourself.
This is not that MVC is "ill suited" for it, but just that control and flexibility has a trade off with more responsibility on your part.
In your case, you simply create a view model with all the fields you want. Then, you create your form to edit those fields. In your controller, you will need to unflatten that view model and create or update the necessary records in the database. It's not difficult, but it's more work than WebForms databinding.
You could look into more advanced tools (commercial) for MVC, such as Telerik's tools, which have developed more of a databinding like interface, but MVC is not a drag-n-drop technology, and requires you to hook things up and write the various logic for what is done.
If you need drag-n-drop, databound functionality, then no.. MVC is not the correct technology. But then WebForms requires you to accept many compromises as well, and ties your hands in many ways.
You could use partial views, however I seldom use them. I prefer to instead use Editor/DisplayTemplates as these take care of naming your form fields correctly, even for collections and complex objects. PartialViews tend to have lots of gotchas if you aren't careful. I pretty much only use them as fancy includes, or when using Ajax.
I'm not sure what you meay by "wrap multiple <forms> around everything`. You cannot nest forms in HTML, it's not legal. If you mean place a form around each row of a table, that isn't valid html either in most cases (it's not legal to put a form in a between the table and the tr).
It would help if you had a specific problem that you could ask about, vague objections don't help us solve your issue.
You can accomplish anything in MVC that you can in WebForms. The difference is MVC will usually require you to write more code as it doesn't really offer you any "controls" to drop on your page.
In WebForms, it's easy to create a master/detail view with a GridView, FormView and then wrap everything in an UpdatePanel for automagical AJAX support.
In MVC, while you do have helpers like the WebGrid and AjaxHelpers extension methods, creating views and/or pages requires more understanding of how things work to get the desired functionality. When I start a new MVC project, here's what I include:
Backbone.js - client-side "ORM" that performs CRUD operations
against RESTful* APIs
Knockout.js - client-side view models and
real-time data-binding for your views
Knockback.js - wraps
Backbone models in Knockout view models
Using these three frameworks, you can quickly create powerful single-page apps using MVC and WebAPI.
Related
does it make sense to use KnockoutJS Viewmodels in combination with ASP.NET MVC3 or 4? Because it is not very DRY, isn't it? I have to write models for EF, Viewmodels for the MVC Views and Viewmodels for Knockout... and i lose a lot of magic. Automatic client-side validations for example.
Does it make sense to use MVC at all if one sticks with the MVVM Pattern?
With Knockout Mapping, you can automatically generate a KO view model from your MVC view model.
This is a proper pattern: your models are raw entities, your data. Your views are the UI. And your view models are your models adapted to that specific view.
This may be an unpopular answer, but I don't use ko.mapping to translate my C# POCOs into JS viewmodels. Two reasons, really.
The first is a lack of control. ko.mapping will turn everything into an observable if you let it. This can result in a lot of overhead for fields that just don't need to be observable.
Second reason is about extensibility. Sure, ko.mapping may translate my C# POCOS into JS objects with observable properties. That's fine until the point you want a JS method, which at some point, you invariably will.
In a previous project, I was actually adding extra methods to ko.mapped objects programmatically. At that point, I questioned whether ko.mapping was really creating more problems than it solves.
I take on board your DRY concerns, but then, I have different domain-focused versions of my POCOs anyway. For example a MyProject.Users.User object served up by a UserController might be very different from a MyProject.Articles.User. The user in the Users namespace might contain a lot of stuff that is related to user administration. The User object in the Articles namespace might just be a simple lookup to indicate the author of an article. I don't see this approach as a violation of the DRY principle; rather a means of looking at the same concept in two different ways.
It's more upfront work, but it means I have problem-specific representations of User that do not pollute each others' implementations.
And so it is with Javascript view models. They are not C# POCOs. They're a specific take on a concept suited to a specific purpose; holding and operating on client side data. While ko.mapping will initially give you what seems to be a productivity boost, I think it is better to hand-craft specific view-models designed for the client.
btw, I use exactly the same MVC3/KnockoutJS strategy as yourself.
We use knockout Mapping to generate the KO view models well.
We have a business layer in a separate project that does CRUD, reporting, caching, and some extra "business logic". We aren't going to be using EF, or something similar. Currently we've defined c# classes as MVC models, and our controllers call the business layer to construct the Models that are defined in the usual place in our MVC app. These C# models get serialized as JSON for use in our pages.
Since everything we do in the browser is c#/JSON based using knockout, we aren't using MVC models in the traditional MVC way - everything gets posted as JSON and serialized to c#, so we don't use MVC model binding, validation, etc. We're considering moving these models to our business layer so they can be tested independently of the web app.
Se we'll be left with an MVC app that has controllers and views, but no models - controllers will get models that are defined in the business layer. We're nervous about departing from the normal MVC structure, but a KO/javascript based client is fundamentally different from a DOM based client that MVC was originally built around.
Does this sound like a viable way to go?
I work now on project which mixes MVC3 and knockouts and I have to tell you - it's a mess...
IMO it's nonsense to force some patterns just to be up to date with trend.
This is an old topic, but now in 2014 (unfortunately) I still feel this question has a huge relevance.
I'm currently working on a project which mixes MVC4 with knockoutjs. I had some difficoulties to find whichs part should be handled on which side. Also, we needed a "SPA-ish" kind of architecture, where each module has its own page, but then inside that module there is only AJAX interaction. Also faced some heavy validation scenarios, and needed to provide user (and SEO) friendly URLs inside each module. I ended up with the following concept, which seems to be working well:
Basic MVC and .NET side roles:
Handling authentication and other security stuff.
Implementing the Web API interface for the client-side calls (setting up viewmodels, retrieving and mapping data from the domain, etc.)
Generating knockout viewmodels from my (pre-existing) C# viewmodels with T4 templates, also including knockout validation plugin extensions from .NET validation attributes. (This was inspired by this aticle). The generated viewmodels are easily extensible, and the generation can be finetuned with several "data annotation"-like custom or built-in attributes (such as DefaultValue, Browsable, DataType, DisplayFormat, etc.). This way the DRY doesn't get violated (too much).
Providing strongly typed, but data-independent partial view templates for each submodule (each knockout viewmodel). Because property names on C# viewmodels are same as in KO models, I can benefit from the strongly typed helpers specifically written for KO bindings, etc.
Providing the main view for each module similarly to previous point.
Bundling and minification of all scripts and stylesheets.
Basic client-side roles:
Loading the initial state of all viewmodels encapsulated into one module page, taking the whole URL into account with a simple route parser implementation.
Handling history with history.js
Data-binding, user interaction handling.
Posting relevant parts of viewmodels to the server, and processing the returned data (usually updating some viewmodel with it).
I hope this could help anyone else who feels lost in the world of trendy technologies. Please, if anyone has any thought on this, feel free to post any question or suggestion in the comments.
Ive been doing a bit of research / reading into mvc recently and was just wondering what the main purpose is.
is it as some people say to seperate the logic from the html
or to create clean url's
i could be missing the point completely, but asp.net forms really seperates the logic from the html and if you just want clean url's why not use a mod_rewrite rule?
MVC is a software engineering concept which is used more widely than just in ASP.net.
In a nutshell it encourages strong separation of:
business logic (the Model) the code which does all the brute force work behind the scenes; dealing with the database, performing large calculations; and
user interface logic (the View) the code which presents information to your users in a pretty way.
The C is for Controller - the ligaments that bind the bones of the model and the muscles of the views and allow them to communicate with each other cleanly.
You are correct that 'normal' ASP.net uses code-behind files so that page markup is kept separate from the code that generates that markup (in contrast to languages like PHP where code is embedded directly amongst HTML), but MVC ASP.net encourages even more separation in the ways I described above.
Take a look at this tutorial for a more detailed discussion of the pattern. Also take a look at this SO question
The MVC pattern has nothing to do with rewriting URLs. ASP.net MVC might make this easier but that is not by any means it's main purpose.
Testability is a big benefit of using ASP.NET MVC. It is non-trivial to write unit tests for ASP.NET winforms. It is much easier to unit tests for Controllers.
If you are doing MVC correctly, your views should be very light, and a lot of your logic is implemented in the Controllers.
Let me compare the two for you:
Asp.net web forms
They matured the old ASP technology that was much more like PHP. Code and presentation were piled up in the same file. Asp.net web forms upgraded this model by providing a mechanism of separating the two. But they built on top of the good things that windows application developers had. The drag drop interface creation with control events just like they exist in a windows application. Event thought code was separate from HTML, they were not separated. You still reference a lot of view controls in your codebehind, hence they're still very much bound to eachother.
Therefore it was rather easy to start developing on Asp.net web forms. But non savvy developers soon got to a bottleneck they didn't know existed (like slow postbacks due to huge view state etc.). Technology used some tricks to make this work. But on a serious large scale application this became quite a problem. Developers had to mingle their code to make it work with Asp.net web forms framework. Their complex forms had complex codebehinds with hard maintainable code with complex state.
The good (as well the bad) thing were at that time rich server controls. Nowadays with web 2.0 they don't seem rich anymore since they don't actually support client side functionality as much as they should. So Microsoft decided to also cram in something else. Update panels. That made partial rendering (and Ajax) possible with almost a flick of a finger. But it came with a cost. Everyone that used (uses) it soon realised it's not a viable solution that a professional application could implement.
Asp.net MVC
Now we have a new technology that doesn't have much in common with Asp.net web forms except for its first part of the name. MVC framework actually does separate code from user interface (view). Controller actions (code that executes on any HTTP request) is kept small and doesn't do anything with visualisation (it doesn't bind data to certain controls etc.). Controller action barely prepares data for the view to either consume or not. It's up to the view. Controller code doesn't in any way shape or form reference any view controls or anything. They're actually separate in MVC.
Views on the other hand just display and provide data. They can be partially or fully rendered. They support Ajax functionality to the point that everyone would like to use. Actually everything is separated into basic little things. Divide et impera (divide and conquer) seems to be the save-line here.
There's not hidden functionality. No flirting with windows development. It pure request response framework. Developer has the ability to 100% control the visual aspect of their app. But for the cost of not having rich controls out of the box. Those may be provided by the community or some developers prefer to create per purpose controls that serve the process much better.
Which one is better then?
Both have their pros and cons. But if you decide to build a semi complex, modern and maintainable application I'd suggest you give MVC a go.
But if all you need to do is a 15 screens application (without any particular interface requirements) it would be much faster to create it using Asp.net web forms.
MVC is a design pattern. Its purpose is to separate business logic and presentation details.
ASP.Net MVC is a mechanism to create web applications using ASP.Net and the MVC pattern.
One of the features of ASP.NET MVC is the ability to use SEO friendly URLs to provide commands to the controller part.
You can do as you have stated but ASP.Net have provided you a mechanism to do this easier.
The way ASP.Net Webforms was designed is that it made it easy for you drag controls on to the web form and code the logic underneath. ASP.Net MVC is designed so you separate your concerns easier.
The URL part of the ASP.NET MVC framework is just a modern phenomena to produce search engine friendly urls. They've infact been around long before the Microsoft team decided to add them to the framework (which required IIS7 before it could be done with no IIS extension).
The greatest pros in my view come from being able to test more easily, and separating off the parts of your application more cleanly. The whole ActionResult architecture of the ASP.NET MVC framework makes it very easy to switch from AJAX to plain out POSTs.
Delphi 5 use to employ the MVC model for its ISAPI extensions, 10 years ago.
MVC is not just an ASP.net thing, it is a design pattern that was widely accepted before it was created within the .NET framework, the thing about MVC is the separation of data from presentation(user interaction) from the business layer. It was just a way for Microsoft to offer that type of design pattern under the .NET framework
Although guys before me already give enough answers to the queston of purpose of ASP.NET MVC there is one thing I would like to add.
The ASP.NET Web Forms tried to abstract html and web from web development. That approach lead to the lacks in performances and usage of rich javascript frameworks.It was possible to create web application without actual knowledge of the web.
And to answer to you initial question, the purpose of ASP.NET MVC, I'll quote Dino Esposito:
With ASP.NET MVC, you rediscover the good old taste of the Web—stateless behavior, full control over every single bit of HTML, total script and CSS freedom.
MVC existed long before people tried to use it in HTML pages. The main reason for MVC is to get a grip on the logic to drive your application. MVC allows you to clearly separate things that should be separate: The model, code which converts the model value for the display and the code which controls the model.
So this is not related to HTML or URLs in any way. It's just that MVC makes it really simple to have clean HTML and simple URLs.
We're building about 10 ASP.NET MVC sites which have a common set of features (and corresponding URLs, Routes, Controllers, Actions, and Views). The sites will also all share a base set of domain objects (e.g. users, companies) and base attributes on those objects (e.g. name, address, etc.).
But each site will also be highly customized and extended from the base. For example, our site for large, public companies will have "Subsidiary" and "Stock Symbol" fields on the Company domain object, while our site for startups will have a "Venture Firm" and and "Funding" attributes. Look and feel will also vary considerably, although we're trying to keep HTML as consistent as possible (modulo extra form fields for extra domain object attributes, etc.). We'll also be overriding images sparingly, so we can, for example, re-use the same button graphics across sites.
Anyway, we're trying to figure out how best to factor and architect things so that we can reuse as much code and as many tests as possible without limiting our freedom to add per-app attributes and vary the UI between apps.
I'm familiar with how to handle limited-customization multi-tenancy like you find in StackOverflow/SuperUser/ServerFault (or MSDN/TechNet for that matter), where the UI is a little different and the data model is more-or-less identical. But when the models and UI are very different (but inherit from a common base), I'm less sure how to proceed.
I'm less worried about operational issues, since we'll probably be running each site in a separate appdomain and hosting them on separate databases. I'm more worried about reducing long-term code maintenance costs, increasing agility (e.g. easy to add new features to the base without breaking derived apps), and realizing short-term dev-/test-cost savings as we build our 2nd, 3rd, 4th, etc. site.
I'm looking both for high-level guidance and suggestions, but also concrete suggestions for how to make that guidance real using modern ASP.NET MVC practices.
I realize this is a very general question, but for starters I'm looking for both high-level guidance as well as concrete tips-n-tricks for how to apply that guidance with ASP.NET MVC, including things like:
recommendations where to split base/derived across Visual Studio projects
source control tips to avoid forking
database schema tips (FWIW, our databases are all small-- under 10K rows per table, so dev/test cost is more of an issue than DB perf)
tips about re-using Controllers/Views/etc. corresponding to the "base" model attributes, especially re-using UI for things like "new customer" forms which will have a mix of base and derived attributes.
Anyone have good advice for how to architect a multi-tenant app like this?
Here's what we do, and it works pretty well for about 8 sites currently.
Define a core MVC project for your Controllers, ViewModels, HttpApplication, routes, etc. This will compile into a DLL and compromise the bulk of your site.
Create a basic set of default views, scripts, images, etc. for your site. These will server as defaults for your individual sites.
Per client, create any custom controllers, routes, etc that you'll need in a project that compiles to another dll.
Also per client, recreate any views, scripts, images that you'll want to use.
To make the above steps work together you'll need to write a little glue. The first piece of glue is a custom view engine. You'll want to customize the standard view engine to first look for views in your client-specific folder, and then the default folder. This lets you easily override the default layout per client.
The second method of getting everything working is to have your core application load the routes, controllers, etc from your client specific assembly. To do this I use the Managed Extensibility Framework (MEF) to expose a single Register method. Calling this method on my client assembly code registers the routes and any other client-specific needs.
Here's a general view of what my site folder structure looks like, with SiteContent being checked for views first:
- AppContent
- AppContent/Static
- AppContent/Static/Images
- AppContent/Static/Scripts
- AppContent/Static/Styles
- AppContent/Views
- AppContent/Views/Shared
- SiteContent
- SiteContent/Static
- SiteContent/Static/Images
- SiteContent/Static/Scripts
- SiteContent/Static/Styles
- SiteContent/Views
- SiteContent/Views/Shared
- web.config
- Global.asax
I have helpers that I can use like SiteImage and AppImage for use in my views. Also, I make each of my client sites use certain specific names for their master pages, that I don't ever define in my AppContent defaults.
I realize this is a rough overview, but it is working well enough for us right now.
I'm involved in a similar type of "suite" of projects currently which is focused on allowing customers to apply for products online but have very similar requirements for what information to collect, where the only differences are around product specific pieces of information or slightly different legislative requirements.
One thing that we have tried to do is create pages (model, view and controller combinations) that are reusable in themselves, so any application can use the page to capture information but redirect to the next page which may be different depending on what type of product is being applied for. To achieve this we are using abstract base controllers in the form of the template method pattern that contain basically all the required controller logic (including action methods with their applied action filters) but then use abstract methods to do the specific stuff such as redirecting to the next page in the process. This means that the concrete implementation of the controller used by specific application page flows may contain only one method which returns a RedirectToActionResult corresponding to the next page in the flow.
There is also quite a bit of other stuff that handles going backwards and those kinds of navigational things, but with the help of action filters you can get it set up that you don't have to worry about it once you get it up and working.
There are also base model objects which contains common functionality, be it validation logic or state persistence logic.
The data captured during the application process is persisted in database as xml serialized model objects which can then be pulled out and de-serialised once the application is completed and spat out in whatever format to whatever system the backend operations staff use to process applications.
The implications of this is that we have a project structure that consists of a base dll that contains top level abstract classes, interfaces and utility classes as well as html helpers, action filters etc. Then we have mvc projects which contain the concrete implementations of the base controllers, models etc as well as the views and masterpages.
The hardest thing is sharing views and I don't think we have properly got this sorted yet. Although with MVC 2.0 containing Areas I think this will become less of an issue but I haven't had a good play with it yet. (see Scott Gu's post on 2.0: http://weblogs.asp.net/scottgu/archive/2009/07/31/asp-net-mvc-v2-preview-1-released.aspx)
One thing I have POCed that looks like it will work is using a base MVC project to contain common views and then extending the default view engine to search that project on the web server when looking for a view to render (which is quite easy to do). Areas though is a far nicer solution.
As for source control, we are using svn and I think you are reasonable in being concerned about branches. It is not something that we have had to deal with yet, but we are probably going to go with git as it seems to make the process of branching and merging much less painful.
Not sure whether this helps you much but I would definitely recommend keep in mind abstract controllers and models, and also look at how you can use html helpers and and partial views to group similar pieces of functionality.
Mike Hadlow goes into good detail on how to accomplish this:
http://mikehadlow.blogspot.com/2008/11/multi-tenancy-part-1-strategy.html
One way to do this is to use branching in a source control system.
The main branch is for the common functionality. You then have a branch for customization and can merge changes out to the customization or back to the main branch.
Is it considered a bad practice to use code-behind with ASP.NET MVC Views? Got into a bit of a debate about this with my colleagues today and I was wondering the community's thoughts.
Obviously, this isn't an option when using another MVC like Rails, which makes me think it's relied on more as a crutch for those accustom to working with traditional ASP.NET Web Forms applications.
I would say that it's a bad practice to use code-behinds with ASP.NET MVC. MVC allows separation of concern where presentation logic (in Views) are separated from application logic (in Controllers). Using code-behinds will mix presentation logic and application logic inside the code-behinds, whereby defeating some of the benefits of MVC.
Certainly the authors of ASP.NET MVC In Action advise against it, and I agree. It isn't necessary, so why do it? In the early betas a code-behind file was included, but this was removed at RTM (or shortly before).
Typically, it simply encourages you to do more non-view work than you should in the view, as it is out of sight / out of mind.
I used code-behind extensively on my first ASP.NET MVC (Preview 3!) project - primarily for doing stuff like casting ViewData["foo"] into strongly-typed data objects, gathering view data into IEnumerables so I could loop across it, that kind of thing.
With the introduction of strongly-typed views, and pragmatic use of the (horrifically-named) Model-View-ViewModel pattern, I haven't missed code-behind at all since it was removed from the project framework just before the final release.
I now strongly feel that whatever processing you're doing in your view's code-behind, you are far better off modelling the result of that processing in your ViewModel, allowing the controller to perform the actual processing, and keep the view as simple and lightweight as you can. That'll let you test the processing logic, it makes the views easier to modify, and creates - I think - a much more elegant separation between transforming your data for display, and actually displaying it.
Yes the codebehind has long been the secret hiding place of business logic which as we all know should not be at the View level.
Code behind has been removed to stop naughty developers from being tempted.
I would recommend avoiding the codebehind in an MVC app at all costs. Using the code behind negates some of the values you get by using the MVC Framework such as separation of concerns, etc. You want to have your data access, business rules, type conversion and that sort of thing applied in the Model. If you find you need to convert your data types like Dylan mentioned, you may want to make ViewModels. The ViewModel would basically be the data from the actual Model you would like to display, in the format you wish to display it in.
Its probably best to avoid putting anything in the code behind when using MVC.
I would be interested to hear which part was being debated about, to go in the codebehind?
If you new to Asp.Net MVC, I really recommend spending some time going through the Nerd dinner example. There's a free EBook and source available here http://nerddinner.codeplex.com/.
Creating the simple demo from scratch is a great way to learn.
After doing this, it may shed some light on where the code you have in the codebehind, could alternatively go.
Note: If you do follow the EBook, grab the latest site.css file from codeplex, otherwise the virtual earth maps won't be aligned properly.
HTH
Ralph
It should be noted that "Code Behind" is a feature of the Web Forms view engine. It really has nothing to do with ASP.NET MVC itself.
For example, the Razor view engine in MVC3 does not even support it.
I would answer your question this way: If you cannot switch view engines without rewriting your controllers (or even your models) then you are not using the MVC pattern correctly.
Probably most of what you are doing in the .aspx.cs file should really be done before the model (or View Model) gets passed to the view. That said, in projects that I have migrated from ASP.NET Web Forms to ASP.NET MVC, I left a lot of the Code Behind in place. For example, I find it cleaner and more pleasing to use a Repeater control than to try to use a 'for' loop in Web Forms. I am still just iterating over View Model data after all. So why not? Separation of concerns is preserved (perhaps to a greater degree in fact).
I mean, why should "best practice" for Web Forms suddenly be the wrong way to do a Web Forms View? As a simple example, consider a Repeater that assigns a different CSS class to every second row of a table. Why should my controller (or even my model) care? Trying to put this kind of logic inline in Web Forms quickly devolves into tag soup and complete spaghetti. Now imagine something more complicated.
I have left Master pages in place that build the menus in the code behind. Again, all data comes from the View Model. I do not see why using GridView or other controls in this way should be a problem either.
I usually disabled ViewState in Web Forms anyway and did the data binding in "Init". Still, there would often be a small ViewState that I could not get rid of. I put some code in "Render" that moves this to after the form (it defaults to before). When moving to MVC, I sometimes left this code in. So, I have ASP.MVC sites that do indeed use Code Behind. I am just careful that it code that is specific to the view.
On new projects, I generally have found less of a need for Code Behind on most pages. Thankfully, view engines like Razor have made mixing code and mark-up in-line a lot less painful to write, read, and maintain.
Looking at MVC framework, it seems we require more of classic ASP knowledge then ASP.NET postbacks and Viewstates. Are we moving backwards to complex UI + code logic in the actual frontend HTML markup?
We're moving back to not trying to abstract away fundamental concepts like HTML and HTTP Requests. On the UI end, that translates into the Views being more tightly integrated with the output, which isn't a bad thing. the classic ASP model translated into having everything tightly integrated with the output, which is a bad thing.
One could argue that the MVC paradigm is a step backward if you consider the ASP.NET paradigm a step forward, I guess. Personally I always thought it was much easier to write clean separated code in classic ASP, rather than .NET where display output text usually got mashed into code blocks where it was impossible to access with a standard HTML editor. I always thought the ASP.NET architecture was more about pushing .NET than improving the overall structure of we application, so in that sense MVC is a step forward.
This is funny that you mention this ... I was having the same conversation with a co-worker today.
Is it a step moving backwards? I don't think so ... while in classic asp you had a some complex logic in the UI, from what I can see with MVC, the complex logic should still be in your business objects, and any complex interaction with the object should be done via the Controller.
The goal, again, from what I can see, is to keep the UI trim and fit when it comes to actual business logic. Any additional bloat would be caused by making the UI more user friendly, with the likes of AJAX and JQuery.
This is just my initial observation regarding MVC. It is a very cool technology, especially with how it sits on top of REST, makes it very easy to work with from other technologies.
I'm looking forward to trying it out in a couple of future projects!
If you are seeing complex code logic in the View relative to the Models and Controllers, than perhaps you are approaching it the wrong way.
In the pure sense, you should be able to switch out the view (XML instead of HTML let's say) with minimal work. That could only happen if the data logic is contained in the models and the business logic ins contain in the controllers.
So, if you were displaying a shopping cart, the view might only have code that writes out the product quantities and totals. The model class(es) would hold the product data and the controller would do all the processing such as adding products and checking out.
The entire point of MVC is for separation of code. Models should contain all of your business logic, the View should just handle the output to the user, and the Controller should glue those two pieces together.