C# - An Architectural / Looking For Design Pattern ?
Feb 26, 2011
So yesterday my mate and myself had this duscussion about the architecture of this e-shopping website that im developing. Note that I work with ASP.NET for this. He was quite surprised to learn that I do not keep the Items added to the shopping-cart in an ArrayList or other Generic list but rather i insert them straight to the database using LINQ To Entities. Could I pass only for this web app and not use n-tire or should I do as my friend suggested which is, have methods that perform updates, deletions etc..
Now that the next version of ASP.NET MVC is being prototyped and previewed (ASP.NET MVC 3 Preview 1 came out a couple of weeks ago), I wonder if we should call the attention of the Core Dev team (S Hanselman, Phil Haack and all) to this "feature."there a easy/non tacky way of associating subdomains → areas?Something like: [URL]Also, whats the best accepted design pattern in implementing PRG pattern in ASP.NET MVC? I guess it should also get some official loving in MVC 3.
I sell products throgh my website. Recently we've been given a list of rules that need to be checked against each order, to make sure it's not fraudulent. So this list of rules/fraud indicators will change and grow so I want to make sure it's easily maintainable and really solid. I'm thinking I have an abstract class rule that each of the rules implements.
abstract class Rule { public string Message; public bool Success; public void CheckOrder(OrderItem currentOrder); } class FakeCreditCardNumberRule : Rule { public string Message = "Fake CC Number Rule"; public void CheckOrder(OrderItem currentOrder) { currentOrder.CreditCardNumber = "1234-5678-9012-3456"; Success = false; } } class ReallyLargeOrderRule : Rule { public string Message = "Really Large Order Rule"; public void CheckOrder(OrderItem currentOrder) { currentOrder.ItemsOrder.Count > 100; Success = false; } }
Then I'm thinking of having a class that accepts an Order object in it's costructor and checks though the list of rules. Something like:
class FraudChecker { List<Rule> rules; public FraudChecker(OrderItem currentOrder) { foreach(var rule in rules) { rule.CheckOrder(currentOrder); } } }
So I was trying to think of the best place/best way to populate the FraudChecker.Rules list and started thinking there might be some nice design pattern that does something like what I'm doing. Has anyone seen a design pattern I should use here? Or can anyone think of a good place to populate this list?
I am planning to generate the UI from database.The platfrom will be ASP.net.Can anyone help in identifying the best design pattern/Architecture that suits for generating the UI and events dynamically.
suggest me a good design pattern for implmenting the following? I have an object say myObject. This myObject is created using few inputs from the UI. After the creation of myObject. This object will be passed to few methods.. like method1(myObject);
method2(myObject);... method5(myObject);etc. Each methods will prepare the input for successive methods call. For example method1(myObject) will set the values necessary for the operation of method2.Then method2(myObject) will set up the values necessary for the operation of method3 and so on..Same object is used as the argument for every method calls.Which design pattern can be implemented?
I'm looking to build an ajax page; it's a reporting page. By default, load today's report. On the page there's a calendar control and when the user clicks on a date, reload the gridview with the corresponding data. Is it considered good practice to do the following:
1) on the first page load, query the data for the page
2) put the query result in the session object and display it in a gridview
3) if the user requests new data, get new data from the query with different parameters
4) put the result of the second query in the session object and display it
5) if the user then requests the data from the first query, get it from the session object
6) do the sorting and paging with the data held in the session.
Note: the data of each query will contain about 300-500 rows and about 15 columns. I'd like to do all this with ajax calls. What are some suggestions and pitfalls to avoid.
Firstly - I'm not asking this question How to include a web service in MVC3? I know where the button is :-)
I'm trying to find an example of best practices of how to use the new DI / Common Service Locator framework in order to make web service calls (and code dependent on web service calls) testable. I've no experience of using NInject or the like - is that the way to go?
I visited this Link to study about Factory design pattern.http://wiki.asp.net/page.aspx/310/factory/ But i am confused about it still. What i understood is that we must use an Interface to define a class .In the interface we will give the prototype of functions and later on we will define it in concrete class. Is that simple concept is Factory design pattern ?
We have a big portal that needs user registration to allow them use its services. It's already done in .NET and SOL Server 2005. we are in the phase now of discovering all the problems of the current registration system to build a new robust flexible one that can be extended easily and can be more usable for all services.
the best practice for a designing a simple CRUD application with some screens updating various tables (like admin pages to maintain static data for an application). the simplest way would be to drag a data grid/gridview, bind it to a dataset and use a data adapter for CRUD operations. but if this application needs to be scalable, lets say to add any extra UI/business logic in future, then is there any design pattern that can with this? should I be using an object data source control and bind it to business objects instead? or are there any better ways of doing it? should I build a complete layered application or will that be overengineering for this requirement?
In one of the interview, I was asked why should we have to go for Single Design pattern, instead of just creating static methods. Because creating static methods also serve the same purpose, i.;e avoiding flooding of objects.
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?
I'm trying to write a web app using 4-tier design pattern ( Data Store, DAL, BLL and UI). Among other things this app would also implement a forum.
Suppose I want to move a thread from one forum to another. In order to do this, UI layer must pass down to other layers the ID of a thread and the ID of a forum to which I wish to move this thread ( UI would pass these parameters by calling method A in BLL layer and A would in turn call method B in DAL layer... ).
a) Now should one of the bottom layers provide some sort of checking mechanism to ensure that the two ID arguments supplied by UI layer really represent an existing thread and an existing forum or is it the responsibility of UI layer to provide valid ID values?
EDIT:
I would consider the ability to pass invalid IDs a bug.
Should non existing ID be considered a bug just in the case of moving a thread, or also in the case of displaying a thread. Thus when user navigates to page Showthread.aspx?ID={0}, if query string parameter ID references non existing ID, If none of the layers check for the validity of ID, then GridView simply won't display any
"But in this case it doesn't look like the ids are in any sort of list. If they were one could only assume that this would never happen as I assume the lists would be populated by a stored procedure or a DAL procedure that pulls all valid IDs."
But even if user chooses IDs from a set of list, by the time it posts the page back, the DB table containing this ID could be changed in the mean time by admin or whomever?!
I am currently working on a document management system in ASP.NET 3.5 using the Telerik AJAX toolkit. It consists of masterpage with a title banner across the top and a RadTreeview down the left hand side for navigation through the site. The treeview uses a combination of static nodes and dynamic ones. The dynamic nodes are populated via a webservice. When a node is clicked the relevant page is navigated to, reloading the masterpage and displaying the content of the target page.
The problem comes from the fact the treeview's dynamic nodes are populated via a webservice and therefore as the user navigates through the tree to find a document the treeview behaves as you would expect. However, when you get to the bottom of a tree of dynamic nodes the navigation to the page of the navigateurl causes the relevant page to be loaded and then the treeview resets itself to a collapsed state. This means the user could be deep in a nest of documents but when they view one, the tree collapses and they have to start their navigation all over again. This limitation is not going to be acceptable from an ease of use perspective.
According to Telerik, this is the designed behaviour for performance reasons - the node only ever worries about populating the next set of nodes and therefore the treeviews state is not remembered in viewstate.
So, the meat of question is. Is the masterpage/async treeview navigation design pattern a valid one? Are there any other ways to have an ajax treeview on a masterpage, that remembers it's state when another page is navigated to? I have considered a siglepage/updatepanel/partial page rendering model but the opinions I've seen on the net infer that this is bad idea. It confuses users that expect back/forward browser behaviour to navigate through the site but in a single page world they would end up leaving the site.
I also thought that maybe using a single page container and an iframe may work but this seems to be moving away from the "standard" design pattern of using masterpages.
design pattern that works well with Visual Studio data tools against an MS SQL server; to retrieve a subset of an object's fields for all rows, and then on-demand retrieve the remainder for one row. I.E. just the small summary fields that I will serialize to a master grid view, then the larger properties including a large blob that I will render in a detail view. The performance hit from retrieving the large blob with the master result list would be too great.
The data shape is static, and I can define two separate data classes to match the specific summary vs. detail information returned. However that sounds anti-pattern-ish, to define the data classes specifically to suit the presentation layer. It also presents another problem, how to translate from the summary item to the detail item in an object-oriented way?
I am a newbie to asp.net and work in a firm where the projects are quite small.
I was told by my manager that in a few weeks or so we would be getting a bigger project and I need to be well versed with Design Patterns and N tier arcihtecture.
I would really appreciate if someone could provide me some links and also drop me a few sentences on how this things are useful?
We have an ASP.NET MVC site that uses Entity Framework abstractions with Repository and UnitOfWork patterns. What I'm wondering is how others have implemented navigation of complex object graphs with these patterns. Let me give an example from one of our controllers:
[code]....
It's a registration process and pretty much everything hangs off the POCO class Person. In this case we're caching the person through the registration process. I've now started implementing the latter part of the registration process which requires access to data deeper in the object graph. Specifically DPA data which hangs off Legal inside Country.
The code above is just mapping out the model information into a simpler format for the ViewModel. My question is do you consider this fairly deep navigation of the graph good practice or would you abstract out the retrieval of the objects further down the graph into repositories?
Does anyone have a working pattern for converting a GET-POST-GET pattern to asny?
I'm encountering the following issues:
1. You cannot mix Sync and Async action methods SubmitForm(), SubmitFormAsync(bool? confirm), SubmitFormCompleted() ... (because the resolver gets all confused ... it doesn't use the HTTP verb to decide who to target. BTW: I think that's poor design, or a bug)
2. Renaming the get method name to something else eg: SubmitFormConfirmation(), SubmitFormAsync(bool? confirm), SubmitFormCompleted() would be very awkward if it works ... because you have to doctor the <form markup to specify an action name.
3. You cannot give them all async names SubmitFormAsync(), SubmitFormAsync(bool? confirm), submitFormCompleted(), because the call just keeps malfunctioning. It sometime even behaves as if you are requesting a delete of something.
Can someone give an insight from an actually working sample.
