29.7. Exercises: Angular, Lesson 2

Let's build an interactive web page that allows us to review data for our astronaut candidates and select crew members for a space mission.

29.7.1. Starter Code

The starter code for the exercises is in the same repository that you cloned for the chapter examples.

Note

Remember that the repository contains a master branch with all the starter code as well as a solutions branch showing the completed exercises.

The solutions provide a resource for you to check if you get stuck. However, for best results you should make a valiant attempt at solving the tasks before looking at "the answers".

Also, if your code works but is different from the solutions, that is OK. There are usually multiple ways of solving the same problem.

From the lesson2 folder in VSCode, navigate into the exercises/src/app/candidates folder. Open the candidates.component.html and candidates.component.ts files.

Access lesson 2 exercises in VSCode.

In the terminal, navigate into the lesson 2 exercises folder. Enter npm install to add the Angular modules, then run ng serve. When you open the web page in your browser, it should look like this:

Starting setup for exercises.

29.7.2. Candidates Column

Examine the candidates array in candidates.component.ts. It contains one object for each animal astronaut. We want to start by listing the names of the animals in the "Candidates" column of the web page.

  1. Find the "Candidates" section in candidates.component.html. Use *ngFor in the <li> tag to loop over the candidates array and display each name in an ordered list.
  2. We want each name to be interactive. Add a click event to the <li> tag. When a user clicks on a name, set the variable selected to be equal to the chosen candidate.

Properly done, your output should behave something like this:

Candidate results.

29.7.3. Candidate Data Column

When we click on a candidate's name, we want their information to appear in the "Candidate Data" column. If no candidate is selected, we want the space under the heading to remain blank.

  1. In the <p></p> element underneath the "Candidate Data" heading, add labels for a candidate's Name, Age, Mass, and Sidekick.
  2. Add placeholders to display the candidate's data next to each label.
  3. Use *ngIf inside the <p> tag to check if a candidate has been selected. If so, display the labels and the data.
  4. Next, create a way to clear the data. In the <button> tag for "Clear Data & Image", add a click event that sets selected to false.

Properly done, your output should behave something like this:

Candidate Data results.

29.7.4. Sidekick Image Column

Every good hero needs a loyal sidekick, and our candidates are no exception!

When we click on a candidate's name, we want an image of their sidekick to appear under the "Sidekick" column. If no candidate is selected, we want this area to remain blank.

  1. In the <img> tag, use *ngIf to check if a candidate has been selected.
  2. Replace the generic {{placeholder}} with the image property of the candidate.

Properly done, your output should behave something like this:

Sidekick image results.

29.7.5. Selected Crew Column

Once we select a candidate, we want an option to add them to the crew of the next space mission.

  1. In candidates.component.ts, code an addToCrew function that takes an object as a parameter.
  2. If the candidate is NOT part of the crew, the function should push them into the crew array. Candidates who are already part of the crew should be ignored.
  3. In candidates.component.html, add a "Send on Mission" button next to the "Clear Data & Image" button.
  4. Add a click event to the button to call the addToCrew function. When clicked, pass the selected candidate as the argument.
  5. Under the "Selected Crew" section, use *ngFor to loop over the crew array and display each name.

29.7.5.1. Clear Crew List

  1. Add a "Clear Crew List" button under the "Selected Crew" list.
  2. This button should only appear when the crew array contains data. Use *ngIf to make this happen.
  3. Add a click event that clears the crew array.

Properly done, your output should behave something like this:

Crew list results.

29.7.6. Bonus Missions

29.7.6.1. Fine Tune the Buttons

  1. Update the Send on Mission button to appear only if a candidate has been selected.
  2. Make the Send on Mission button disappear if the selected candidate is already part of the crew.
  3. Make the Send on Mission button disappear once three crew members have been assigned to the mission.

29.7.6.2. Change the Mission Name

We can make the Mission Name heading interactive. When clicked, we want to present the user with an input box to enter a new name. For this exercise, the ng-template code you need is at the bottom of candidates.component.html.

  1. Replace line 2 in candidates.component.html with <h2 class="centered" *ngIf = "!editMissionName; else editMission" (click)="editMissionName = true">Mission Name: {{missionName}}</h2>.
  2. When clicked, the ng-template code executes. Update the input tag with a keyup.enter event. The event should call the changeMissionName function and pass the new name as an argument.
  3. In candidates.component.ts, code a changeMissionName function to update the name of the mission.
  4. After changing the mission name, set editMissionName to false.

29.7.7. Bonus Results

After finishing the bonus missions, your output should behave something like this:

Bonus content behavior.