Let's add an endpoint to fetch a movie, which is enriched with some metascore info from the OMDB API.
Go to http://www.omdbapi.com/, scroll down to By ID or Title.
We are going to search for a movie using the ?t query parameter. If we go to http://www.omdbapi.com/?t=Titanic&apikey=7f9b5b06, we will see the following response:
{
Title: "Titanic",
Year: "1997",
Rated: "PG-13",
Released: "19 Dec 1997",
Metascore: "75"
...
...
...
}
We want to extract the Metascore and return it along with our Movie.
We can now implement a Decoder instance to convert a Json response from OMDB to a Metascore.
Complete exercise
This has mostly been implemented for you. We use Http4s' Uri type to encode the movieName so spaces become %20, for instance, and then we make a request using an Http4s HTTP Client.
Hint: We want to start by converting the String in the response body into a Metascore. For the purpose of this exercise, let's convert any failures from Circe into a None.
Complete exercise
Moving on to the Service, we can see it has access to two functions. The first one is to fetch a Movie and the second is to fetch a Metascore. More concretely, the first is the Postgresql database call and the second one is the OMDB API call.
For the purpose of this exercise, if we get no Metascore, we want to error.
Complete exercise
Run unit test: FetchEnrichedMovieServiceSpec
Again, this is not much different than what we've seen. If we have Some(enrichedMovie) we want to return Ok(...). If we have None, we want to return NotFound(). If we have a Left, we want to call the ErrorHandler.
If you try to convert an EnrichedMovie to Json using .asJson, you will get a compilation error. This is because we have not created the Encoder instance for EnrichedMovie.
Work on the Controller and also the Encoder. You will have to create your own custom encoder this time because we want to return a flat Json, even though EnrichedMovie is a nested structure.
Complete exercise
Run unit test: FetchEnrichedMovieControllerSpec
In AppRuntime, FetchEnrichedMovieController has been constructed using FetchEnrichedMovieService, and passed into AppRoutes.
AppRoutes has an unused handler called fetchEnrichedMovieHandler. Update the GET /movies/{id} route to check for the existence of a ?enriched=true query parameter and call fetchEnrichedMovieHandler if the query parameter exists.
You can pattern match on a query parameter as such:
case GET -> Root / "movies" / LongVar(id) :? OptionalEnrichedMatcher(maybeEnriched) => ???
Run unit test: AppRoutesSpec