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Okay, we now have a repository,
that's great, but

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let's take another look at our design.

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As we work on our project
implementing this series and

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artist controllers, we'll continue to
add methods to our repository class.

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Overtime, our repository
can become bloated.

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Also, our repository is currently
concerned about persisting data for

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more than one entity type,
comic books and comic book artists.

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We might think of our design is violating
the single responsibility principle,

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which states, that every class
should have responsibility

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over a single part of the functionality
provided by your application.

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Luckily for us,
the solution to this problem is easy.

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Instead of a single repository class,
we can have multiple repository classes,

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each focused on a single entity type.

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Let's split out all of the repository
methods that deal with comic books,

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into its own repository class.

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To start, let's add a class named
ComicBooksRepository to the shared class

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libraries date folder.

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By default, classes use the internal access modifier, if one isn't specified.

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That restricts access to this class to
code within this project or assembly.

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Adding a public access modifier,

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will make this class accessible to
code within the web app project.

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Now, let's set up our
database context instance.

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At a private field of type
Context named _context.

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And a constructor that accepts
a context instance, and

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uses that the set the private field.

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Remember, this is the same pattern
that we used for the repository class,

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which allows the controller to
manage the lifetime of the context.

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Now, we can select and cut the ComicBook
related methods to the clipboard.

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GetComicBooks, GetComicBook,
AddComicBook, UpdateComicBook,

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DeleteComicBook and
ComicBookSeriesHasIssueNumber.

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And paste those methods from the clipboard
into the ComicBooksRepository class.

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Let's also move over to
ComicBookArtistRoleCombination method.

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Looks like we've got some
using directives to add.

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For the namespaces,
ComicBookShared.Models and

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System.Data.Entity.

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Now that we have a repository
that's focused on comic books,

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we can simplify our method names.

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Consumers of this class will already know
that they're working with comic books.

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So we can remove any references to
comic book from the method names.

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For instance,
we can change GetComicBooks to GetList,

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And GetComicBook to simply Get.

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And we can remove ComicBook
from the CRUD method names.

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For now, I'll leave the validation
method names as they are.

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Currently, we're instantiating
an instance of the repository

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in the BaseController class.

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Doing this in the controller base class,

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made the repository available
to all of our controllers.

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When you have a single repository class,
this approach makes a lot of sense.

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But when you have multiple focus
repository classes, it's probably best to

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allow each controller to instantiate
the repositories that they need.

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Given that, let's update
the ComicBooksController to instantiate

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an instance of our new
ComicBooksRepository.

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Add a private field for the repository.

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And add a default constructor to
instantiate an instance of the repository.

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We need an instance of
our database context to

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pass into the ComicBooksRepository
constructor.

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In the BaseController class,
the context is currently a private field.

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We'll need to switch that over to
be in a protected property, so

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that it's accessible to
the descendant controller classes.

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And update any references to the private
field to use the new property.

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Back at the ComicBooksController, update
the call to the ComicBooksRepository

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constructor to pass in the base
controller's context property.

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Now we can update all of the bad
repository references and method calls.

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Repository.GetComicBooks becomes,

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_comicBooksRepository, GetList.

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Repository.GetComicBook becomes
_comicBooksRepository get.

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Repository.AddComicBook becomes
_comicBooksRepository.Add.

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Another call to
Repository.GetComicBook to update.

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Repository.UpdateComicBook becomes
_comicBooksRepository.Update,

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and another call to
Repository.GetComicBook to update.

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Repository.DeleteComicBook becomes
_comicBooksRespository.Delete,

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Repository.ComicBookSeriesHasIssueNumber
becomes

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_comicBookRepository.ComicBookSeriesHasIs-
sueNumber.

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And that fixes all of the build
errors in the ComicBooksController.

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Let's build the project
by pressing Ctrl+Shift+B.

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And the ComicBookArtistController has
some build errors that we need to fix.

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This controller will also need
an instance on the ComicBook repository.

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You might be tempted at this point to just
move the ComicBooksRepository instance

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into the BaseController.

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But let's hold off on doing that.

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I suspect that the series and

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artist controllers won't need
an instance of that repository.

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So let's stick with our plan of
letting each controller instantiate

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the repositories that they need.

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First, the private field.

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Then, the default constructor.

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And update the bad method calls

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Repository.GetComicBook becomes

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_comicBooksRepository.Get.

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Once more, And

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Repository.ComicBookHasArtistRoleCombina-
tion

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becomes
_comicBook.Repository.ComicBookHasArtistR-

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oleCombination.

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And now the project is
successfully building again.

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In repository class,
we have six methods left.

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GetSeriesList, GetArtists,
GetRoles, GetComicBookArtist,

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AddComicBookArtist, and
DeleteComicBookArtist.

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Let's keep series, artist, and

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role related methods in this class,
at least for now.

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Later on,
when we have more than one method for

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each of those entity types,
we'll add a repository for those types.

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But let's go ahead and

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move the ComicBookArtist-related
methods to a new repository class.

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In fact,
let's make that your next exercise.

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Add a new repository class,
move the GetComicBookArtist,

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AddComicBookArtist, and
DeleteComicBookArtist methods to it.

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And update the ComicBookArtist
controller as needed,

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to get the project building again.

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See you after the break.