go-playground/projects/greenlight/cmd/api/movies.go

package main

import (
	"errors"
	"fmt"
	"net/http"
	"strconv"

	"greenlight.debuggingjon.dev/internal/data"
	"greenlight.debuggingjon.dev/internal/validator"
)

func (app *application) createMovieHandler(w http.ResponseWriter, r *http.Request) {
	var input struct {
		Title   string       `json:"title"`
		Year    int32        `json:"year"`
		Runtime data.Runtime `json:"runtime"`
		Genres  []string     `json:"genres"`
	}

	err := app.readJSON(w, r, &input)
	if err != nil {
		app.badRequestResponse(w, r, err)
		return
	}

	// Copy the values from the input struct to a new Movie struct.
	movie := &data.Movie{
		Title:   input.Title,
		Year:    input.Year,
		Runtime: input.Runtime,
		Genres:  input.Genres,
	}

	// Initialize a new Validator.
	v := validator.New()

	// Call the ValidateMovie() function and return a response containing the errors if
	// any of the checks fail.
	if data.ValidateMovie(v, movie); !v.Valid() {
		app.failedValidationResponse(w, r, v.Errors)
		return
	}

	// Call the Insert() method on our movies model, passing in a pointer to the
	// validated movie struct. This will create a record in the database and update the
	// movie struct with the system-generated information.”
	err = app.models.Movies.Insert(movie)
	if err != nil {
		app.serverErrorResponse(w, r, err)
		return
	}

	// When sending a HTTP response, we want to include a Location header to let the
	// client know which URL they can find the newly-created resource at. We make an
	// empty http.Header map and then use the Set() method to add a new Location header,
	// interpolating the system-generated ID for our new movie in the URL.
	headers := make(http.Header)
	headers.Set("Location", fmt.Sprintf("/v1/movies/%d", movie.ID))

	// Write a JSON response with a 201 Created status code, the movie data in the
	// response body, and the Location header.
	err = app.writeJSON(w, http.StatusCreated, envelope{"movie": movie}, headers)
	if err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) showMovieHandler(w http.ResponseWriter, r *http.Request) {
	id, err := app.readIDParam(r)
	if err != nil {
		app.notFoundResponse(w, r)
		return
	}

	// Call the Get() method to fetch the data for a specific movie. We also need to
	// use the errors.Is() function to check if it returns a data.ErrRecordNotFound
	// error, in which case we send a 404 Not Found response to the client.
	movie, err := app.models.Movies.Get(id)
	if err != nil {
		switch {
		case errors.Is(err, data.ErrRecordNotFound):
			app.notFoundResponse(w, r)
		default:
			app.serverErrorResponse(w, r, err)
		}
		return
	}

	err = app.writeJSON(w, http.StatusOK, envelope{"movie": movie}, nil)
	if err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) updateMovieHandler(w http.ResponseWriter, r *http.Request) {
	id, err := app.readIDParam(r)
	if err != nil {
		app.notFoundResponse(w, r)
		return
	}

	// Retrieve the movie record as normal.
	movie, err := app.models.Movies.Get(id)
	if err != nil {
		switch {
		case errors.Is(err, data.ErrRecordNotFound):
			app.notFoundResponse(w, r)
		default:
			app.serverErrorResponse(w, r, err)
		}
		return
	}
	// If the request contains a X-Expected-Version header, verify that the movie
	// version in the database matches the expected version specified in the header.
	if r.Header.Get("X-Expected-Version") != "" {
		if strconv.FormatInt(int64(movie.Version), 32) != r.Header.Get("X-Expected-Version") {
			app.editConflictResponse(w, r)
			return
		}
	}

	// Use pointers for the Title, Year and Runtime fields.
	var input struct {
		Title   *string       `json:"title"`
		Year    *int32        `json:"year"`
		Runtime *data.Runtime `json:"runtime"`
		Genres  []string      `json:"genres"`
	}

	// Decode the JSON as normal.
	err = app.readJSON(w, r, &input)
	if err != nil {
		app.badRequestResponse(w, r, err)
		return
	}

	// If the input.Title value is nil then we know that no corresponding "title" key/
	// value pair was provided in the JSON request body. So we move on and leave the
	// movie record unchanged. Otherwise, we update the movie record with the new title
	// value. Importantly, because input.Title is a now a pointer to a string, we need
	// to dereference the pointer using the * operator to get the underlying value
	// before assigning it to our movie record.
	if input.Title != nil {
		movie.Title = *input.Title
	}

	// We also do the same for the other fields in the input struct.
	if input.Year != nil {
		movie.Year = *input.Year
	}
	if input.Runtime != nil {
		movie.Runtime = *input.Runtime
	}
	if input.Genres != nil {
		movie.Genres = input.Genres // Note that we don't need to dereference a slice.
	}

	v := validator.New()

	if data.ValidateMovie(v, movie); !v.Valid() {
		app.failedValidationResponse(w, r, v.Errors)
		return
	}

	// Intercept any ErrEditConflict error and call the new editConflictResponse()
	// helper.
	err = app.models.Movies.Update(movie)
	if err != nil {
		switch {
		case errors.Is(err, data.ErrEditConflict):
			app.editConflictResponse(w, r)
		default:
			app.serverErrorResponse(w, r, err)
		}
		return
	}

	err = app.writeJSON(w, http.StatusOK, envelope{"movie": movie}, nil)
	if err != nil {
		app.serverErrorResponse(w, r, err)
	}
}

func (app *application) deleteMovieHandler(w http.ResponseWriter, r *http.Request) {
	// Extract the movie ID from the URL.
	id, err := app.readIDParam(r)
	if err != nil {
		app.notFoundResponse(w, r)
		return
	}

	// Delete the movie from the database, sending a 404 Not Found response to the
	// client if there isn't a matching record.
	err = app.models.Movies.Delete(id)
	if err != nil {
		switch {
		case errors.Is(err, data.ErrRecordNotFound):
			app.notFoundResponse(w, r)
		default:
			app.serverErrorResponse(w, r, err)
		}
		return
	}

	// Return a 200 OK status code along with a success message.
	err = app.writeJSON(w, http.StatusOK, envelope{"message": "movie successfully deleted"}, nil)
	if err != nil {
		app.serverErrorResponse(w, r, err)
	}
}