The Model-Repository-Service-Validator-View-ViewModel-Controller Design Pattern
Jan 19, 2010
When I first heard about ASP.NET MVC, I was thinking that would mean applications with three parts: model, view, and controller.
Then I read NerdDinner and learned the ways of repositories and view-models. Next, I read this tutorial and soon became sold on the virtues of a service layer. Finally, I read the Fluent Validation documentation, and I'll be darned if I didn't end up writing a bunch of validators.
Tonight, I took a step back and thought about what had become of my project. It seems to have become the victim of the design pattern equivalent of "feature creep". Somehow I'd gone from Model-View-Controller to Model-Repository-Service-Validator-View-ViewModel-Controller. You want loosely coupled and DRY? We got your loosely coupled and DRY right here! But I'm wondering if this could be a case of too much of a good thing.
Am I right to be concerned? Or is this actually not as crazy as it sounds? On one hand, it seems crazy to have so many layers. On the other hand, every layer has a clearly defined purpose that makes sense to me. Have your MVC applications turned into MRSVVVMC apps too? If not, what do they look like? Where's that right balance?
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Feb 4, 2011
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Dec 8, 2010
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[Code]....
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Oct 13, 2010
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[code]....
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Dec 13, 2010
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Mar 4, 2011
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I've got problem with my app .
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[Code]....
[Code]....
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[Code]....
[Code]....
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Aug 21, 2010
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Jun 22, 2010
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Mar 18, 2011
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Mar 8, 2011
I've been using MVC for the last year and unfortunately I am stuck adding features to an existing web forms site. The site makes heavy use of inline SQL and it is kind of all over the place. Using an ORM is not going to happen either and wouldn't address the problem of keeping queries all in one place.
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Feb 15, 2010
I am building an application using asp.net mvc, DI, IoC, TDD as a bit of a learning exercise.
For my data access I am using the repository pattern. Now I am looking at membership and how this can work with the repository pattern. I am currently using a Linq to Sql repository but don't want to be tied to SQL Server for membership.
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Oct 18, 2010
I am sort of using a repository pattern to extract information from a database. I have two classes, report and reportRepository.
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Oct 8, 2010
How Can I Pass data(not the part of model) to Controller from View? View Code
[Code]....
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Jul 8, 2010
This is possibly the worst kind of religious debate -- a religious debate with practical consequences. But it's one that needs to be had, and I can't seem to fit it in my tiny head. Here are the pros and cons of the pattern as I know them:
Pros:
-Encourages DRY (don't repeat yourself) design in that identical queries are written only once per set of query conditions
-Facilitates unit testing by allowing itself to be abstracted into an interface
-Creates an opportunity for business-level validation
Cons:
-Breaks DRY philosophy in that you're generally repeating your database schema
-In a sense breaks separation of concerns, because the query concerns of the controller and view frequently become the concerns of whoever is maintaining the repository
-Determining what should be a repository and what should be returned as a raw associated ORM entity becomes an ambiguous art
To me it seems like all this stuff should be done at the ORM level, but Entity Framework has much fewer hooks than Linq to Sql does, yet Entity Framework tends to be regarded as being more robust, so it seems that this is by design, and that the designers of EF are in fact encouraging another layer. Are there any tools or anything that I could be using for this? Am I missing something?
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Dec 21, 2010
I am currently using the 3-tier Repository pattern in my application. Actually it's the first time for me to implement a design pattern at all! i used to put all my code in the so called now presentation layer.
i want to implement data validation, for example, password should not be more than 10 characters and have to contain special characters. Should i put this code in the data access layer? but my data access layer contains methods that take the DTO as a parameter for example
[Code]....
and the same is for other CRUD operations (DELETE and UPDATE), so implementing such validation on the DAL would make me duplicate the code in each and every method that accepts the DataObject as a paramter. Same holds for the business logic layer where i am using it as a proxy between the presentation and the data access layers.
Eventually it has to use the same Data Objects as parameters. This only leaves me with one option which is to do the validation on the Data Object part. But i think this is not the essence of the respository pattern which states that the Data object class should only be a "container" class with no behavior.
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Nov 2, 2010
I'm working on adding an HtmlHelper for pagination, but I am unsure where the proper and/or most beneficial place to put certain parts of the pagination code from a performance and maintainability standpoint.
I am unsure if the Skip(), Take() and Count() portions of Linq to SQL data manipulation should live within the repository or the controller.
I am also unsure if their order and where they are used affects performance in any way.
If they live within the repository from my understanding this is how it would work:
1. I would pass the pageIndex and pageSize as arguments to the repository's method that grabs the data from the database.
2. Then grab the full data set from the database.
3. Then store the count of TotalItems of that full data set in a variable.
4. Then apply the Skip() and Take() so the data set retains only the page I need.
5. Display the partial data set as a single page in the view.
If they live in the controller from my understanding this is how it would work:
1. I would grab the full data set from the repository and store it into a variable inside of the controller.
2. Then get the count of TotalItems for the full data set.
3. Then apply the Skip() and Take() so the data set retains only the page I need.
4. Display the partial data set as a single page in the view.
Inside the controller (I realize I will incorrectly get the page count here and not TotalItems):
[code]....
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Jan 17, 2011
i am using EF4 and StructureMap in an asp.net web application. I am using the repository/unit of work patterns as detailed in this post. In the code, there is a line that delegates the setup of an ObjectContext in global.asax.
EntityUnitOfWorkFactory.SetObjectContext(() => new MyObjectContext());
On the web page code-behind, you can create a generic repository interface like so ...
IRepository<MyPocoObject> ds = ObjectFactory.GetInstance<IRepository<MyPocoObject>>();
My question is what is a good approach to refactoring this code so that I can use more than one ObjectContext and differentiate between them in the code-behind? Basically i have two databases/entity models in my application and need to query them both on the same page.
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Jan 26, 2011
Just wondering, in an ASP.NET MVC3 environnement with entity framework. Should the Unit of Work point to the service layer or the repository (and then the repository point to the service layer) ?
Ive saw two example:
* One where the unit of work and repository both have an instance to the service layer..
Link: Entity Framework 4 CTP 4 / CTP 5 Generic Repository Pattern and Unit Testable
Doesn't use a service layer but its obvious that one could be use in that case.
* Second where the unit of work have an instance to the repository which have an instance to the service layer..
[URL]
What would be better ?
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May 6, 2010
I'm working through the nerddinner MVC tutorial, but making slight changes for it to fit my project.I have a FormViewModel which works fine in creating a SelectList for the Edit View, however it doesn't work for the Create view as the selecteditem is null;
var btypes = from BikeTypeID
in db.BikeTypes
select BikeTypeID;
[code]...
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Aug 26, 2010
Curious what the best practice is for returning errors to a view from a controller where the error isn't really a validation error, but more like "user not found" or "service timeout" type of errors. (in ASP.NET MVC2 framework)
I've been adding them to the ModelState's model errors, but that doesn't seem appropriate. (although easy to implement and maintain)
Example - A user tries to log in, and their credentials do not match a known user.
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Feb 8, 2011
We are moving from ASP.NET Web Forms to MVC 2.0. In most of our projects we have a typical setup to communicate with a database.
Common (objects/entities like 'SiteMenu' and 'Users')
Business Logic Layer (with calls to de Data Access Layer)
Data Access Layer
The DAL has a DatabaseHelper with common database operation, an OdbcHelper with database specific operations (eg MySQL) and a StoredProcedure class with all the stored procedures.
How is this design translated into a repository design? We want to use our own database helpers instead of NHibernate etc.
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Nov 21, 2010
I have 2 repository that I'm trying to use in the same controller and cant find out how
This is what I'm tried :
[Code]....
for the first one it was working(VortRepository but I cant add the second )
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