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POST movies

This endpoint is different than the GET ones because there is a request body that we receive from the client that we need to decode and turn into a Movie.

1. MovieValidationError (2 min)

We have built an ADT that represents all possible validation errors for a NewMovieRequest.

If the name is empty, return a MovieNameTooShort and if the synopsis is empty, return a MovieSynopsisTooShort.

2. NewMovieRequest vs ValidatedMovie (3 min)

We have two different models here. A NewMovieRequest represents a request that has been successfully decoded containing a name and synopsis to save into the database.

However, at the point of decoding, we do not know whether the name and synopsis obey our business rules.

We need to validate this model and if it is valid, we create a different type ValidatedMovie that represents this. The two types contain the same information, but by making them two distinct types, we can enforce additional type safety and better readability.

3. NewMovieValidator (exercise) (5 min)

Build a validate function that takes a NewMovieRequest and returns either an Invalid[NonEmptyList[MovieValidationError]] or a Valid[ValidatedMovie].

Remember what you learned from ValidationExercises.

Complete exercise

Run unit test: NewMovieValidatorSpec

4. SaveMovieService (exercise) (5 min)

We can see SaveMovieService has a saveMovie function taken in as a dependency. It is of type ValidatedMovie => IO[MovieId].

The save function accepts a NewMovieRequest and returns a IO[ValidatedNel[MovieValidationError, MovieId]]. We want to validate the request, if it is valid, we save the movie and return the MovieId, otherwise we return all the errors.

Complete exercise

Run unit test: SaveMovieServiceSpec

5. SaveMovieController (exercise) (10 min)

The Controller is a little different this time. We have the entire request as an argument to the function. We want to decode the request into a NewMovieRequest and then pass that into the saveNewMovie function in the class constructor.

After that, we want to attempt as usual and handle each possibility.

You will need to complete the following in order to get the Controller to compile:

  • Decoder[NewMovieRequest]
  • Encoder[MovieValidationError]
  • Encoder[MovieId]

6. NewMovieRequest decoder (exercise) (5 min)

We need to describe how to convert from a Json into NewMovieRequest.

Hint: The incoming JSON body is the same shape as our NewMovieRequest case class.

{
  "name": "Titanic",
  "synopsis": "A movie about ships"
}

Complete exercise

7. MovieValidationError.show and MovieValidationError encoder (exercise) (10 min)

Implement the show function first. This is a way to go from our type into a String.

Complete exercise

Run unit test: MovieValidationErrorSpec

Next, create an Encoder instance to convert our type into Json.

Complete exercise

8. MovieId encoder (exercise) (5 min)

We also need a way to convert a MovieId into Json.

Complete exercise

9. Finish off SaveMovieController! (5 min)

Complete exercise

Run unit test: SaveMovieControllerSpec

10. Wire it all up in AppRuntime (5 min)

Now let's wire the Service and Controller up in AppRuntime.

Pass the newly instantiated saveMovieController into AppRoutes.

11. Update AppRoutes (5 min)

Change AppRoutes to accept a SaveMovieController and then call saveMovie given the request!

Note that req@POST... means that req is an alias for the value on the right hand side.

Start the app using ./auto/start-local and test it out!

Test queries:

curl -H "Accept: application/json"  -X POST -d "{\"name\": \"\", \"synopsis\": \"\"}" http://localhost:9200/movies

curl -H "Accept: application/json"  -X POST -d "{\"name\": \"Space Jam\", \"synopsis\": \"A movie about basketball\"}" http://localhost:9200/movies

curl http://localhost:9200/movies/2