Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>You actually just created a repository only you call it a 'data access layer' which is, in my opinion, not a good name since Entity Framework is the data access layer. A repository is an abstraction on top of a data access layer, Entity Framework in this case. </p> <hr /> <blockquote> <p>Is it wrong to create a new DbContext on each call to DAL ? Any Performance hit?</p> </blockquote> <p>Nope, it's just fine, but it might cause trouble when you fetch an entity in one instance of <code>DbContext</code>, and try to update it in another instance.</p> <hr /> <blockquote> <p>Would you use Linq2SQL in a new project ?</p> </blockquote> <p>Nope, Microsoft proposed Entity Framework as the successor of L2SQL and active development of it has stopped.</p> <hr /> <blockquote> <p>Any other recommended structure for using EF ? Examples? :)</p> </blockquote> <p>The approach you use, specific repositories, will result in a lot of redundant code. You could create a generic repository implementing an interface:</p> <pre><code>public interface IRepository&lt;TEntity&gt; where TEntity : class, new() { IEnumerable&lt;TEntity&gt; GetAll(); TEntity GetById(int id); IQueryable&lt;TEntity&gt; Table { get; } } </code></pre> <p>And an implementation of this:</p> <pre><code>public EfRepository&lt;TEntity&gt; : IRepository&lt;TEntity&gt; where TEntity : class, new() { private readonly DatingSiteContext _context; public EfRepository() { _context = new DatingSiteContext(); } private IDbSet&lt;TEntity&gt; Entities { get { return _context.Set&lt;TEntity&gt;(); } } public IEnumerable&lt;TEntity&gt; GetAll() { return Entities.ToList(); } public TEntity GetById(int id) { return Entities.Find(id); } public IQueryable&lt;TEntity&gt; Table { get { return Entities; } } } </code></pre> <p>You can use this repository in your controller like this:</p> <pre><code>public class HomeController : Controller { private readonly IRepository&lt;User&gt; _userRepository; public HomeController() { _userRepository = new EfRepository&lt;User&gt;(); } public ActionResult Index() { var users = _userRepository.GetAll(); var inactiveUsers = _userRepository.Table.Where(u =&gt; !u.Active).ToList(); } } </code></pre> <p>This generic repository allows you to create mocked repositories:</p> <pre><code>public class FakeUserRepository : IRepository&lt;User&gt; { // ... } </code></pre> <p><hr /> This approach might seem like a lot of code, but as your entity type amount grows, it will save you a lot of work since all you have to do is create an <code>IRepository&lt;&gt;</code> field in a controller. Yet you have a lot of flexibility with the <code>IQueryable&lt;&gt;</code> property which allows deferred execution.</p> <p>I'm not saying this is the best method, just one I use regularly in projects. I have to say that I usually write a business (service) layer between the controller and the repositories. I keep my business logic and complex Linq queries (and their execution) there. I also use an IoC container which handles the lifetime of my objects (instances of <code>DbContext</code> and services for example). See <a href="https://stackoverflow.com/questions/3058/what-is-inversion-of-control">this question</a> for more information about that.</p>
    singulars
    1. This table or related slice is empty.
    1. POASP.Net MVC & Entity Framework project architecture WITHOUT repository pattern
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USHenk Mollema
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POASP.Net MVC & Entity Framework project architecture WITHOUT repository pattern
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI would rephrase that. A Repository is an abstraction on top of a data access layer, not necessarily an ORM.
      singulars
      1. PO
      1. USErik Funkenbusch
    2. CO@MystereMan you're right, I'll update my answer soon.
      singulars
      1. PO
      1. USHenk Mollema
    3. COThanks for detailed response :) 1. You wrote "might cause trouble when fetch an entity in one instance of DbContext, and update it in another instance.” Does the generic repository described above help solve this problem? 2. I tried using Generic interface for the repositories but I found that 90% of the time my queries are a lot more specific/complex and I just don’t use the generic GetByID or GetAll , would you still see a point in created a generic interface? 3. In the generic class you created the DbContext once per repository, why is that? Would that require using dispose function?
      singulars
      1. PO
      1. USRuSh
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload