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Lab 4 - Injecting Repository Into Controller


In this lab, you'll have the API controller use the newly created MealOrderRepository to store new MealOrders.

Annotation Reference

This reference of annotations is good to keep handy:

A. Clean Up MealOrder

Now that we have MealBuilder, we can get rid of the overloaded constructors in MealOrder. They were useful once, but they're now "cruft" and we want to delete unused code.

  1. Run all tests!
  2. Delete all of the constructors from MealOrder
  3. Run all tests.
  4. If you had any usages of these non-default constructors, replace them with using the MealBuilder
  5. Are tests still passing?

B. Store Created MealOrders in Repository

In the MealOrderApiController's POST handler, we create the MealOrder, but then toss it out once we've asked for the price. Now that we have a repository, we can use it to store these created orders.

  1. Open up the MealOrderApiController class
  2. Create a default (no-argument) constructor that is empty
    • ? Why do you need to do this?
  3. Create a private member variable that will hold a reference to a MealOrderRepository
  4. Create a new constructor that takes a repository as a parameter and saves it to the member variable
    • This is manual dependency injection
  5. Make sure all tests are still passing.

Before writing any more code, let's write a test that will make sure a new order created via the API stores it in the repository. Add this test to the MealOrderApiControllerTest class:

public void mealOrderIsStoredInRepository() throws Exception {
  MealOrderRepository mealOrderRepository = new MealOrderRepository();

  MealOrderRequest mealOrderRequest = new MealOrderRequest();

  MealOrderApiController controller = new MealOrderApiController(mealOrderRepository);
  MealOrderResponse response = controller.mealOrder(mealOrderRequest);


C. Save New Order to Repository

In the API controller, you'll save the meal order into the repository.

  1. Open up the MealOrderApiController class.
  2. In the mealOrder() method, after creating a mealOrder object, use the repository to save the meal order.
  3. Run the test from above and it should pass. Then run all the tests.

    Run All Tests

    When you run all the tests, two other tests might fail. Why?

    If the two tests, regularBurgerWithLargeFriesIs10Dollars and mealOrderBurgerCheeseWithLargeDrinkIs8Dollars aren't broken, then you're done!

  4. If the two tests are failing with a NullPointerException, you can fix them by always passing in a new MealOrderRepository when instantiating the MealOrderApiController, e.g.:

    MealOrderApiController controller =
            new MealOrderApiController(new MealOrderRepository());


If the tests were broken, what are some other ways to fix them tests?