Task 1: Review the Starter Code

Tip

One essential programming skill that you will develop is the ability to read and understand someone else’s code. This assignment begins with you practicing exactly that. Make sure you carefully examine the provided code BEFORE you start changing things.

Trying to “fix” a code sample before understanding how it works leads to confusion, frustration, and a broken program. DO NOT SKIP the code review!

Carly created a ASP.NET MVC application and filled in some features. She refactored JobData to generate a List of Job objects based on your TechJobs-OO work, and she added controllers and views for a “Home”, “List”, and “Search” page. JobData now also builds Lists for the Employer, Location, PositionType, and CoreCompetency objects.

The Data and Model

The “model” is contained in the JobData class, which is in the Data folder. We put “model” in quotes, since this class isn’t a model in the typical, MVC/object-oriented sense (maybe a better name for this assignment would be TechJobs VC).

The JobData class serves the same purpose as before—it reads data from the job_data.csv file and stores it in a format we can use. In this case, that format is a List of Job objects, which is stored in the Models folder. Note that Carly changed the path to the job_data.csv file to store it in the Data folder too.

You’ll use some of the static methods provided by JobData in your controller code. Since you’re already familiar with these, we’ll leave it to you to review their functionality as you go.

The Controllers

Expand the Controllers folder, and you’ll see that you have three controllers already in place. Let’s look at these one at a time.

The HomeController

This class has only one action method, Index(), which displays the home page for the app. The controller renders the Index.cshtml template (in Views/Home) and provides a fairly simple view.

TechJobs MVC home screen

The ListController

This controller provides functionality for users to see either a table showing all the options for the different Job fields (Employer, Location, CoreCompetency, and PositionType) or a list of details for a selected set of jobs.

If you look at the corresponding page at /list, you’ll see an “All” column in the table. However, this option doesn’t work yet, and you will fully implement the constructor as you work on this project.

At the top of ListController are static Dictionaries that populate ColumnChoices and TableChoices with values respectively. These Dictionaries play the same role as in the console app, which is to provide a centralized collection of the different List and Search options presented throughout the user interface.

ListController also has Index() and Jobs() action methods. The first method renders a view that displays a table of clickable links for the different job categories. The second method needs to render a different view that displays information for the jobs that relate to a selected category. Both of the action methods can obtain data by implementing the JobData class methods.

Jobs() will work similarly to the search functionality, in that we are “searching” for a particular value within a particular field and then displaying jobs that match. However, this is slightly different from the other way of searching in that the user will arrive at this handler method as a result of clicking on a link within the Index.cshtml view, rather than via submitting a form.

The SearchController

Currently, the search controller contains only a single method, Index. It simply renders the form defined in the Index.cshtml template.

Later in this assignment, you will receive instructions for adding a second handler to deal with user input and display the search results.

The Views

Let’s turn our attention to the views.

Bootstrap Classes

The application uses a few Bootstrap classes to style the view content and job tables. You won’t have to explicitly add any Bootstrap classes to your views in this assignment, but it’s a great way to make your sites look good with minimal work.

The List Views

Turn your attention to List/Index.cshtml. This page displays a table of links broken down into several categories. Data from ColumnChoices is used to fill in the header row, and information stored in TableChoices generates the link text.

The most interesting part of this template is how we generate the links:

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   @foreach (var category in ViewBag.tableChoices)
   {
      <td>
         <ul>
         @foreach (var item in category.Value)
         {
            <li>
                  <a asp-controller="List" asp-action="Jobs" asp-route-column="@category.Key" asp-route-value="@item">@item</a>
            </li>
         }
          </ul>
      </td>
   }
  1. TableChoices is a Dictionary from ListController, and it contains the names of the Job fields as keys (Employer, etc.). The value for each key is a List of Employer, Location, CoreCompetency, or PositionType objects.
  2. In line 17, category represents one key/value pair from TableChoices, and in line 21, item represents one entry from the stored List.
  3. We’ve seen some of the syntax to generate a link within a Razor template, but we don’t have as much experience with asp-route-column and asp-route-value.This syntax causes Razor to dynamically generate query parameters for our URL.

In line 24, we set these parameters by using asp-route-column= and asp-route-value=. The values of these parameters are determined dynamically based on @category.key and @item. Since these values come from TableChoices, the keys will be employer, location, etc. The values will be the individual elements from the related List. When the user clicks on these links, they will be routed to the Jobs() action method in ListController, which looks for these parameters.

By the end of your work on this project, clicking on one of the links should display a list of jobs that relate to the choice, via the Jobs() action method.

For now, click one of the Location links. This sends a request as we outlined above, but doing so only leads to an error.

Once you have completed the project, the page you will see at /list/values?column=location&value=... is generated by the Jobs.cshtml template. It has a similar structure as Index.cshtml, but the table consists of only one column.

Note

Select “Kansas City” from the list of locations, and then check the address bar of your browser:

   /list/jobs?column=location&value=Kansas%20City

Razor inserts %20 for us, to represent a space, but this may actually be hidden in your browser’s address bar.

The Search View

Finally, click on Search from the home page, or the navigation bar, and open up Search/Index.cshtml in Visual Studio. You’ll see a search form (in both the browser and template file) that gives the user the option of searching by a given Job field, or across all fields. This is an exact visual analog of our console application.

This template will be used to display search results, in addition to rendering the form. This will give the nice user experience of easily searching multiple times in a row.

Wrap Up the Code Review

Once you understand the controllers and views that are already in place, you’re ready to begin your work.

In Visual Studio, select View > Tasks to pop open a small pane at the bottom of the window. This list is populated by any code comments that start with TODO. You’ll see your tasks listed, and clicking on any one will open the relevant file.

Note

You may not see a TODO #4. This is because TODO comments in views do not always show up in the Task List. If it is not there, check out the Search/Index.cshtml view to locate it!