Single Repository Or Multiple Repositories?
May 1, 2010
In a typical business application, a session is started and persisted across several pages. It is commited only when the transaction is complete. A good example of this is a tax preparation application. Once the session is started, it is persisted through session, cookies, or both. Nothing is written to file, or database, until the entire profile is complete and the refund/return is calculated. In such an ennvironment, is makes a great deal of sense to work with the structure imposed by domain driven design, and using a single repository to simple commit the session. However, there are times when this doesn't translate correctly, even when domain driven design is used.
An example of this is my forum project. While the entities themselves are good targets for domain driven design, I am not sure about the repositories. The basic structure is that a Category has many Forums, a Forum has many Threads, and a Thread has many posts. There are other things in there, but that's enough to describe what I want to get across. If a user has navigated to /Thread/Edit/42, and they have rights to edit it, all I am concerned about is fetching that record and displaying it. On postback, all I want is to be able to save it..................
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Aug 17, 2010
I would like to start a debate on traditional repositories versus one built on the UnitOfWork pattern. In a traditional repository, we wrap inserts, updates and deletes in a transaction, but selects don't really need them. In addition, nhibernate configuration is typically done once per application due to BuildSessionFactory being rather expensive. We often have several repositories of this type (one per aggregate chain). We also need to have projected, ahead of time, exactly what kinds of queries we'll need in order to build the interfaces and concretes correctly. In a single UnitOfWork repository we have the ability to manage both the current session and transaction, perform several operations, and then commit any changes all at once. In such a repository we may opt to put our configuration in the constructor since (typically speaking) no more than one Action is called per request anyway, initializing it in the application doesn't seem like much of an overall gain in speed. I must admit, I'm very temped to use the UnitOfWork pattern, as the following code looks really nice to me:
Csharp Code:
using (IUnitOfWork worker = new UnitOfWork()){// session and transaction are now both set
// save changes to three itemsworker.SaveOrUpdate(item1);worker.SaveOrUpdate(item2);worker.SaveOrUpdate(item3);
// grab a fourth var item4 = worker.Criteria<Foo>().Add(Expression.Eq("title", title)).UniqueResult<Foo>();
// delete the fourthworker.Delete(item4);
// all pending operations are commited or rolled back as a single unit (if one fails, all are rolled back), and then disposed, along with the session}
My proposed UnitOfWork class is rather simple. It implements IDisposable where I use a try-catch-finally in Dispose() to attempt a tx.Commit(), doing a tx.Rollback on failure, and a cleaning everything up in the finally clause. It also exposes common things like SaveOrUpdate, Delete, GetAll, Get, and even a Critera<T>() for custom on-the-spot queries. So what are your thoughts on this? I'd really like to hear about your experience with this pattern.
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May 3, 2010
I have a few repositories in my project. All repositories inherit from an abstract interface repository containing the public datacontext variable and a Save function for the entire DB.
In my controllers I want to make changes to the the db and in one of my functions I'm working with two different repositories. Calling the Save function on each of the repositories I'm using can cause a situation in which one of the calls to Save succeeds and and the other fails resulting in a need of rolling back the changes of the Save function that failed.
What is the best way to work against multiple repositories and access to the DB to avoid such a situation?
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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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May 19, 2010
I have a stored procedure that returns 3 tables within the single recordset it returns. If I set a SqlDataSource to get data from this procedure, it works, but it only returns the first table. I want to have a GridView display the data from the 2nd or 3rd table using a SqlDataSource, but I can't figure out how to specify a particular table.
While there are some posts discussing this out there, I can't get a definitive answer about whether or not this is even possible (?). In a worst-case scenario, I can create another SP that only returns the 3rd table - but that creates a little maintenance headache that I would prefer to avoid.
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Jan 12, 2011
below written question :
1.) What is the name of the OS process in which App Domain resides.
2.)if suppose There are Three Windows application hosted on a same envoirment and two instance is working for each application at a Time, means now total instance are six .what will happen among the below written cases :
a.) There will be six different app domain in a single OS process
b.) There will three app domain(one for each application) in a single OS process and some Parallel thread will be executed in each app domain for another instance.
c.) There will be Three OS process corresponding to each application.
3.) If eveything will remain same except there are three web application in place of windows in point 2, will there be any change in functioning.
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Aug 18, 2015
I have a question in gridview, I want to combine my two or more records into a single cell with two rowsfor Example i have a ID, Name, Year Start, and Year End for Column name in database and i want call it into my gridview that the Year Start and Year End will combine to Year like:
In Database
ID Name Year Start Year End
1 Yourname 2010 2015
In Gridview:
ID Name Year
1 Yourname 2010 2015
in a year column i want it to two row..
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Aug 18, 2015
I want to bind three column with one row in gridview in asp.net with c#,
i want like this,
Name | Info
----------------------
name | lastname
| phone number
| address
I get this by default
name | last name | phone number | address
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Aug 9, 2010
Background: I use stored procedures exclusively for an ASP.NET application. I am using a DataReader to load a dataset object.
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Dec 6, 2010
Could someone explain what happens to the Repositories that are created when they are no longer needed? Are they automatically disposed of, or should we dispose of them manually?
Using EF4 as the DAL, to keep the program efficient I have been building repositories for the Model that abstract the data needed for specific views or actions. I have also used the Iinterface for the methods and call them in the Controller to pass them to the View. At some point the program needs to pass a behavior or request that requires the creation of a new repository and the process may repeat itself over and over again. What happens to the repositories that created for previous views, but are no longer needed? Should the dispose be written into each repository, or does garbage collection take care of this? How should this handled?
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Apr 13, 2010
I've been reading up on MVC 2 and the recommended patterns, so far I've come to the conclusion (amongst much hair pulling and total confusion) that:
Model - Is just a basic data container Repository - Provides data access Service - Provides business logic and acts as an API to the Controller
The Controller talks to the Service, the Service talks to the Repository and Model. So for example, if I wanted to display a blog post page with its comments, I might do:
post = PostService.Get(id);
comments = PostService.GetComments(post); Or, would I do:
post = PostService.Get(id);
comments = post.Comments;
If so, where is this being set, from the repository? the problem there being its not lazy loaded.. that's not a huge problem but then say I wanted to list 10 posts with the first 2 comments for each, id have to load the posts then loop and load the comments which becomes messy.All of the example's use "InMemory" repository's for testing and say that including db stuff would be out of scope. But this leaves me with many blanks, so for a start can anyone comment on the above?
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Mar 9, 2011
Assuming my application did not warrant a full blown DDD setup, would Repositories still be useful? I like the way they shield from implementation details (such as use of Entity Framework) underneath. However Repositories tend to be tied to Aggregate Roots (the concept is still a holy grail to me) by definition.
I suppose the question could also be put as such: if I have a typical 3-tier application, with a business layer facade consisting of "logical grouping" classes based on functionality (rather than aggregate roots as in DDD) such as TradingManager and ContactsManager, would it make sense to also create "logical grouping" repositories. Or perhaps a Data Access Object, which I believe is like a Repository without the aggregate root requirement. Of course I will still have a Model (EF POCOs) that will be passed up and down between the layers.
Also, is what I just described would be considered as a Transaction Script approach? It's certainly not DDD, and not Active Record. I'm not even sure if Active Record exists with EF4 like it does with Nhibernate.
I am trying to understand how others structure n-layered applications when they do not follow DDD.
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Jan 13, 2011
Are there advantages in creating complex types in EF4 Entities and then use the complex properties in the repositories; instead of creating the aggregates in the the repository themselves? I.e. If the customer repository consists of properties of 3 entities: customers, addresses, email would it make sense to create a complex type consisting of the address and email properties, and add them as a complex property of the customer entity then just call the customer entity and the complex property in the repository, rather than just creating the repository class and aggregate the entities in the repository.What are there advantages or disadvantages in doing this in a MVC3 application?
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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 5, 2010
Is there a way to copmile a solution into a single dll?
Said solution may have several custom projects. I want all of them, and all the third party dll's they reference compiled into a single dll.
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Sep 29, 2010
I have a web project which includes two button in a view.when i click a button some textboxes along with that second button have to be visible.After entering data in textboxes,when i am trying to click the second button, its not working.What should i do to make it work?
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Jul 23, 2010
How can I have multiple routes in a single request at global.asax? Error "The incoming request does not match any route."
[code].....
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Mar 3, 2010
I have 4 different select statements which i sequently assign to an sqlDataSource like this:
sqlNoutatiProduse.SelectCommand = select;
and i keep the results in different DataViews like
MySession.Current.dataViewNoutatiProduse1 = (System.Data.DataView)sqlNoutatiProduse.Select(DataSourceSelectArguments.Empty);
Is it possible to combine into a single DataView the results of these queries?
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Mar 6, 2010
I am currently Developing application in MVC2 I want to used mutiple form tags(<form>) in My application. In My View I have Created a table which has Delete option which i am doing through Post for Individual Delete so i have Create form tag for each button. as mention By Stephen Walther [URL] i also want user to give option to delete mutiple records so i am providing them with checkboxes.This form should have all the values of checkboxes and all. so form gets render Like this in browser
[Code]....
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Aug 25, 2010
I want to use my asp.net mvc application with multiple domains (maybe of hundreds),
so I have created custom Route class that matches requests including domain.
Each domain could has different routes, so the number of routes in RouteTable can be huge
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I am considering how it will be efficient?
I have an idea to replace RouteTable.Routes (of type RouteCollection)
with custom one (of type Dictionary<string, RouteCollection>).
But how I can override default route matching mechanism with my custom mechanism which will be two step:
1) retrieve RouteCollection from dictionary based on domain name
2) retrieve specyfic Route object (standard route matching mechanism)
How can I do this?
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May 12, 2010
I'm trying to use ConfigurationManager.AppSettings.GetValues() to retrieve multiple configuration values for a single key, but I'm always receiving an array of only the last value. My appsettings.config looks like
<add key="mykey" value="A"/>
<add key="mykey" value="B"/>
<add key="mykey" value="C"/>
etValues("mykey");
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Mar 30, 2011
There are existing questions that pertain to this subject, but I feel my case may be slightly different(correct me if i'm wrong).
I have two web sites that are almost identical as far as graphics go. They will need only to have a different logo. Additionally I have set up the database so that products can be flagged to show up on either or, or both web sites. Is it possible to set up IIS to point the second web site to the first web site and then have my code determine which domain the request is coming from?
For instance, web site 1 will have domain www.myfirstwebsite.com and the second web site will have a domain like www.mysecondwebsite.com.
If I did go this route I'm guessing I would check in the master page code behinds Page_Load event for the domain and then when I want to display products on my front end I can reference against the variable in the master page.
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Jul 7, 2010
I'm got 2 model objects. Category and CategoryItem. I try to add a CategoryItem to Category in my Controller but It wont save to database, and I know why because I don't know how to call the submitChanges on the add while using repository, I dont got the DBContext right there is you know what I mean?.. here I will show you with code.
[Code]....
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Aug 23, 2010
I need to make multiple button in a single image in asp.net.and need coding also for vb.net.
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Jun 15, 2010
i try to create dynamic control and have a single event handler to ease the fireevent how do i do it?also can i declare a single event handler to parent control and be use by child control of the same type
in example:
creating htmlanchor name aa
aa.Control.Add(any anchor)
after adding the control
declare the event handler
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