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Let's review my solution for finishing the comic book artists controller.
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Welcome back, how did you do with
finishing the ComicBookArtistsController?
0:00
Don't worry if you weren't able to
finish every task in this exercise.
0:04
No matter how far you were able to get,
just the act of trying alone
0:08
will improve your ability to retain what
you've learned so far in this course.
0:13
Let's take a look at my solution.
0:17
I start it with updating
the ComicBookArtistsController
0:19
with a private field for
the database context, and
0:22
instantiated an instance
in the default constructor.
0:25
I also over-rode the base
classes dispose method, so
0:31
I can dispose of the context instance
when the controller is disposed.
0:34
This code is just like the code that
we added to the comic books controller.
0:38
So by adding it to this controller, I've
repeated myself by duplicating that code.
0:42
We'll see in the next section
how we can avoid doing this.
0:48
Now that I had a database
context available,
0:51
turned my attention to completing
the to-dos in the action methods.
0:54
In the add get action method, I added a
query to retrieve the requested comic book
0:58
using the include method to eagerly
load the series navigation property.
1:03
I also passed the context into the view model's init method call.
1:07
Doing that immediately broke the build.
1:12
So I went ahead and
took a bit of a detour and
1:14
updated the viewMethod.Init method with
the parameter for the database context.
1:17
And I added the queries to retrieve
the available artist and roles.
1:27
Both ordered by the respective
entity name properties.
1:33
Before I could update the other action
methods, I needed to take another detour.
1:37
And add a ComicBooKArtists DbSet
property to the context class.
1:42
Adding this property makes it possible to
query directly for a ComicBookArtists.
1:46
As well as add, update, and
delete a CominBookArtists.
1:51
After making that change,
I updated the add post action method
1:55
to instantiate a ComicBookArtists
entity instance.
1:59
Setting the ComicBookId, ArtistId, and
2:03
RoleId property values to their
respective viewModel property values.
2:06
Then I added that entity instance to
the ComicBookArtists DBSet property, and
2:11
called the SaveChanges method.
2:16
That takes care of the happy path.
2:18
If the model state is invalid and
2:21
we have validation messages
to display back to the user,
2:22
we need to set the viewModel's ComicBook
property and call its Init method.
2:25
To set the ComicBook property, I copied
the query from the get at action method,
2:33
and I past the database context
into the Init method call.
2:38
Which had already been updated earlier
with a parameter for the context.
2:43
In the delete get action method I added
a query to retrieve the ComicBookArtists.
2:47
This query eagerly loads multiple
navigation properties including,
2:52
Artist, Role, ComicBook, and
the ComicBook.Series navigation property.
2:57
Noticed I didn't need to add
separate include method calls
3:03
with the ComicBook and
ComicBook.Series properties.
3:06
As everything in the property path
will be automatically included.
3:10
Then in the delete post action method,
3:13
I added the code to delete the
ComicBookArtists using the same technique
3:16
that we use in the ComicBook's controller.
3:20
Lastly, I updated the validate
ComicBookArtists method with a query
3:22
that uses the any operator to check if
there is an existing ComicBookArtists with
3:26
the provided ComicBookId,
ArtistId, and RoleId values.
3:31
You may have done things slightly
differently from how I did,
3:37
and that's okay.
3:40
Often there's more than one way to
implement a feature or solve a problem.
3:42
I'd encourage you to share
your solution with me, and
3:46
others on the Treehouse community.
3:49
Let's review what we
covered in this section.
3:51
We added a database connection string
to our app's configuration file,
3:53
in order to configure the server and
database that EF should use.
3:57
And we saw how to configure the database
initializer using our apps configuration
4:01
file, which prevented us from making
an unnecessary number of calls
4:06
to the database set initializer method.
4:10
We also saw how to manage
the context's lifetime
4:13
by aligning it with
the controllers lifetime.
4:17
And we implemented the necessary reads,
creates, updates, and
4:19
deletes for CcomicBooks.
4:24
In the next section,
4:26
we'll continue to work on
the ComicBook Library Manager web app by
4:27
looking at ways we can improve the design
and organization of our data access code.
4:31
See you then.
4:35
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