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Let’s add a comic book repository to our project to give us a central location for storing and managing our comic book model instances.
Follow Along
To follow along commiting your changes to this course, you'll need to fork the aspnet-comic-book-gallery repo. Then you can clone, commit, and push your changes to your fork like this:
git clone <your-fork>
cd aspnet-comic-book-gallery
git checkout tags/v4.6 -b adding-the-repository
Code
Here’s a copy of the comic books data that you can use in your own repository class.
private static ComicBook[] _comicBooks = new ComicBook[]
{
new ComicBook()
{
SeriesTitle = "The Amazing Spider-Man",
IssueNumber = 700,
DescriptionHtml = "<p>Final issue! Witness the final hours of Doctor Octopus' life and his one, last, great act of revenge! Even if Spider-Man survives...<strong>will Peter Parker?</strong></p>",
Artists = new Artist[]
{
new Artist() { Name = "Dan Slott", Role = "Script" },
new Artist() { Name = "Humberto Ramos", Role = "Pencils" },
new Artist() { Name = "Victor Olazaba", Role = "Inks" },
new Artist() { Name = "Edgar Delgado", Role = "Colors" },
new Artist() { Name = "Chris Eliopoulos", Role = "Letters" },
},
Favorite = false
},
new ComicBook()
{
SeriesTitle = "The Amazing Spider-Man",
IssueNumber = 657,
DescriptionHtml = "<p><strong>FF: THREE TIE-IN.</strong> Spider-Man visits the FF for a very private wake--just for family.</p>",
Artists = new Artist[]
{
new Artist() { Name = "Dan Slott", Role = "Script" },
new Artist() { Name = "Marcos Martin", Role = "Pencils" },
new Artist() { Name = "Marcos Martin", Role = "Inks" },
new Artist() { Name = "Muntsa Vicente", Role = "Colors" },
new Artist() { Name = "Joe Caramagna", Role = "Letters" }
},
Favorite = false
},
new ComicBook()
{
SeriesTitle = "Bone",
IssueNumber = 50,
DescriptionHtml = "<p><strong>The Dungeon & The Parapet, Part 1.</strong> Thorn is discovered by Lord Tarsil and the corrupted Stickeaters and thrown into a dungeon with Fone Bone. As she sleeps, a message comes to her about the mysterious \"Crown of Horns\".</p>",
Artists = new Artist[]
{
new Artist() { Name = "Jeff Smith", Role = "Script" },
new Artist() { Name = "Jeff Smith", Role = "Pencils" },
new Artist() { Name = "Jeff Smith", Role = "Inks" },
new Artist() { Name = "Jeff Smith", Role = "Letters" }
},
Favorite = false
}
};
Additional Learning
For more information on how to move around Visual Studio, see this page on MSDN.
See these MSDN pages for more information on code snippets in Visual Studio.
Keyboard Shortcuts
-
CTRL+TABorCTRL+SHIFT+TAB- Navigate through your open files -
CTRL+SHIFT+B- Build solution
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In this video, we'll be adding a comic
book repository to our project.
0:00
This will give us a central location for
storing and
0:05
managing our comic book model instances.
0:08
We need a location in our project for
our repository.
0:11
Let's add a data folder.
0:15
Right-click on the project in the solution
explorer panel and select the Add
0:17
> New folder menu item,
type the name data and press Enter.
0:22
Now we can add the repository class.
0:28
Right-click on the data folder and
select the Add > class menu item,
0:31
change the name of the class to
ComicBookRepository and press Enter.
0:37
Let's start,
by adding a public GetComicBook method,
0:45
to our repository that returns
a comic book model instance.
0:49
For now, just return null.
0:54
Don't forget to add the using directive
for our ComicBookGallery.models;_ Now
0:57
we can open our comic books controller
class and copy to the clipboard
1:03
the code that instantiates
the comic book model instance.
1:07
Let's switch back to our
comic book repository class.
1:11
Did you know that you can
navigate between your open files
1:15
by holding down the Ctrl key and
pressing Tab?
1:18
Pressing tab multiple times will
cycle through the list of files.
1:22
Holding the Shift key down
in addition to the Ctrl key
1:27
will cycle through the list of files in
the opposite direction when you press Tab.
1:31
Being able to change
the direction is handy
1:36
when you have lots of
files open at one time.
1:39
This Visual Studio feature is simple but
one of my favorites.
1:42
Now let's paste the code
from the clipboard
1:46
just above the return null statement.
1:48
Then replace null with comicBook.
1:51
Let's go ahead and
press Ctrl+S to save the file.
1:55
Let's also collapse the Solution Explorer
panel to give us more room in the editor.
1:59
Okay, so we've made things incrementally
better by moving our comic book
2:04
model instantiation code from
our controller to a repository.
2:08
Unfortunately, our current
implementation has a major downside.
2:13
What if we want to get a comic book other
than the Amazing Spider-Man number 700.
2:18
That's a good comic but our website
isn't going to be very interesting
2:23
if we can only display the information for
one comic book.
2:27
What we need is a list of comic
books that our get comic book method
2:31
can draw upon what it needs to
return a single comic book.
2:35
To do this let's add a private
static field to our repository.
2:39
We'll start with the private keyword
followed by the static keyword and
2:43
our field type which will be
an array of ComicBook objects.
2:48
Name the field _comicBooks.
2:52
We'll also instantiate
the array in line by typing new
2:56
ComicBook brackets followed
by a set of curly braces.
3:01
By making this field static,
we're associating it with the ComicBook
3:07
repository class instead of the individual
object instances of this class.
3:11
This will ensure that we only have
a single copy of the comic book data
3:17
in memory at any given time.
3:21
Next, add our existing ComicBook
to the private field array.
3:23
Starting with the new keyword, select
everything down to the semicolon and
3:27
cut the selection to the clipboard.
3:32
Let's clean up the bit left behind.
3:35
Then paste the clipboard contents
inside of the curly braces, for
3:38
our private field array.
3:42
Let's also add some
additional comic books.
3:44
To save some time,
3:46
I already have the additional
comic book data here in Notepad.
3:48
If you're following along,
I've included a snippet of this code
3:52
in the teacher's notes so
you don't have to type everything out.
3:55
I'll select and
copy this code to the clipboard and
3:59
switch back to Visual Studio.
4:03
Let's add a comma at the end of
our first element press Enter to
4:05
create a new line then
paste from the clipboard.
4:10
Now let's update the GetComicBook
method to use our new private
4:13
field first add an ID parameter of
type int to the method signature.
4:18
That will allow the caller of this method
to pass in the ID of the comic book that
4:23
they're interested in.
4:27
Visual Studio is politely letting
us know that the comicBook variable
4:29
doesn't exist in our current context.
4:32
Let's go ahead and fix that by adding
a ComicBook variable declaration
4:35
just above the return statement.
4:39
Initialize the variable to null.
4:41
Okay, we've got an id on hand we need
to loop over the available comic books
4:44
find the one whose ID matches and assign
that coming book to our return variable.
4:49
Let's use a Visual Studio code
snippet to create our array.
4:54
Type for each to select the for each code
snippet then press the tab key twice.
4:58
There are three items that we
can edit in this code snippet,
5:04
the value variable type and
name and the loop source.
5:08
Pressing tab allows us to move from
one editable item to the next.
5:12
Let's leave the value variable
type as var for the name.
5:18
I like to use the singular version of
the array name that I'm enumerating.
5:22
So comicBook then set the loop
source to _comicBooks.
5:26
Press the Escape key to
exit the code snippet.
5:33
Code snippets can be a great time saver,
you can even create your own.
5:37
To learn more about Visual Studio code
snippets see the teachers notes for
5:41
links to additional resources.
5:45
Hm, Visual Studio doesn't
5:48
like our value variable name.
5:53
A local or parameter named comicBook
cannot be declared in this scope because
5:59
that name is used in an enclosing local
scope to define a local or parameter.
6:00
Okay., what this error messages telling
us is that I already use the identifier
6:01
comicBook for my return variable.
6:06
So I can't reuse that name
from my loops value variable.
6:09
To fix this problem, I'm going to rename
my return variable to comicBookToReturn.
6:13
Don't forget to also update
the return statement.
6:21
Now inside of the loop let's add
an if statement that checks if
6:26
the current comic books id
matches the id argument.
6:30
And if so assigns the comic book to return
variable to the current comic book.
6:34
So while this method will work as is,
6:43
there's an easy improvement
that we can make.
6:45
Once we found the comicBook
that we're looking for,
6:48
there's no need to continue to loop
through the remaining comicBooks.
6:50
We can accomplish this by
adding a break statement
6:54
just after the line where we set
the comicBookToReturn variable value.
6:57
Excellent, congrats on creating
your first repository.
7:02
Typically, repositories retrieve from and
persist data to a database.
7:06
Our data is currently
embedded in our code.
7:12
In future courses, you'll learn how
to move your data into a database.
7:15
Let's build our project,
press Ctrl+Shift+B to build the solution.
7:19
Visual Studio opens the Output window so
that we can monitor the progress of
7:24
the build and
see the results upon its completion.
7:28
We can see here that one project
succeeded and zero failed.
7:31
If you're using GitHub, let's commit our
changes into our commit message of Added
7:35
comicBook repository.
7:41
And click the commit all button.
7:44
Next we need to update our controller
to use our new repository.
7:47
We'll work on that in the next video.
7:52
See you then.
7:54
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