There is no exercise for this endpoint.
We have already implemented an endpoint for you! Let's have a look at it in AppRoutes.
We can see that AppRoutes already has a FetchAllMoviesController in scope. If the incoming request is GET movies, we call the FetchAllMoviesController.
Let's look at the Controller and Service implementations now. Open up the fetchallmovies package in the project. This package contains the Service and Controller for fetching all movies.
The Service has a fetchAllMovies passed in as dependency. The Service is typically where your business logic is, but fetching all movies is extremely simple. All we need to do here is call fetchAllMovies.
More concretely, fetchAllMovies is the function defined in PostgresRepository for fetching all the movies from the database. Let's have a quick look at PostgresRepository, which contains all the logic needed to interact with our database.
We have implemented all the SQL needed to work with Postgres in this file. We are using a library called Doobie. If we look at this file, we have one function for each of our endpoints already implemented. Keep in mind that the return type of each function is an IO.
The function that this endpoint uses is fetchAllMovies.
The Controller takes the function from the Service in as a dependency. Every IO has potential for failure by definition. At this point, we call fetchAll and then we attempt it here, before serving any result to the client. We typically want to defer error handling to the end of our program so we do not have to handle it all over the place.
Now we can pattern match on the result. If we have Right(movies), we construct an 200 Ok(...) response with the movies converted to Json. Otherwise, we pass the error to our ErrorHandler, which we will explain later. We should really be using an Encoder[Movie] here and do movies.asJson but we aren't because we want you to write the Encoder instance for Movie later on. We don't want to give away the answer!
We have written this error handler to convert errors into a nice Json response. Every time you get a Left in your Controller, call this function.
Because AppError is an ADT, if we add a new AppError, we get a compilation error in encodeAppError because of non-exhaustiveness.
In AppRuntime, we instantiate our PostgresqlRepository, our FetchAllMoviesService and FetchAllMoviesController. Then we pass the Controller into AppRoutes.
If we have a look at AppRoutes, we can see that when we call GET movies, we run fetchAllMovies, which calls the apply method in the FetchAllMoviesController.
Run ./auto/start-local
curl http://localhost:9200/movies