Updating MovieModel's method from internal/data/movies.go file. Create the updateMovieHandler function inside cmd/api/movies.go. Adding the route into routes.go to update a movie.

cmd/api/movies.go

@@ -87,3 +87,66 @@ func (app *application) showMovieHandler(w http.ResponseWriter, r *http.Request)
 		app.serverErrorResponse(w, r, err)
 	}
 }
+
+func (app *application) updateMovieHandler(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
+	}
+
+	// Fetch the existing movie record from the database, sending a 404 Not Found response to the client if we couldn't find a matching record.
+	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
+	}
+
+	// Declare an input struct to hold the expected data from the client
+	var input struct {
+		Title   string       `json:"title"`
+		Year    int32        `json:"year"`
+		Runtime data.Runtime `json:"runtime"`
+		Genres  []string     `json:"genres"`
+	}
+
+	// Read the JSON request body data into the input struct
+	err = app.readJSON(w, r, &input)
+	if err != nil {
+		app.badRequestResponse(w, r, err)
+		return
+	}
+
+	// Copy the values from the request body to the appropriate fields of the movie record.
+	movie.Title = input.Title
+	movie.Year = input.Year
+	movie.Runtime = input.Runtime
+	movie.Genres = input.Genres
+
+	// Validate the updated movie record, sending the client a 422 Unprocessable Entity response if any checks fail.
+	v := validator.New()
+
+	if data.ValidateMovie(v, movie); !v.Valid() {
+		app.failedValidationResponse(w, r, v.Errors)
+		return
+	}
+
+	// Pass the updated movie record to our new Update() method
+	err = app.models.Movies.Update(movie)
+	if err != nil {
+		app.serverErrorResponse(w, r, err)
+		return
+	}
+
+	// Write the updated movie record in a JSON response
+	err = app.writeJSON(w, http.StatusOK, envelope{"movie": movie}, nil)
+	if err != nil {
+		app.serverErrorResponse(w, r, err)
+	}
+}

cmd/api/routes.go

@@ -24,6 +24,7 @@ func (app *application) routes() http.Handler {
 	router.HandlerFunc(http.MethodGet, "/v1/healthcheck", app.healthcheckHandler)
 	router.HandlerFunc(http.MethodPost, "/v1/movies", app.createMovieHandler)
 	router.HandlerFunc(http.MethodGet, "/v1/movies/:id", app.showMovieHandler)
+	router.HandlerFunc(http.MethodPut, "/v1/movies/:id", app.updateMovieHandler)
 
 	// Return the httprouter instance.
 	// Wrap the router with the panic recovery middleware

internal/data/movies.go

@@ -109,7 +109,24 @@ func (m MovieModel) Get(id int64) (*Movie, error) {
 
 // Update : Updating a specific record in the movies table
 func (m MovieModel) Update(movie *Movie) error {
-	return nil
+	// Declare the SQL query for updating the record and returning the new version number.
+	query := `
+		UPDATE movies
+		SET title = $1, year = $2, runtime = $3, genres = $4, version = version +1
+		WHERE id = $5
+		RETURNING version`
+
+	// Create an args slice containing the values for the placeholder parameters.
+	args := []any{
+		movie.Title,
+		movie.Year,
+		movie.Runtime,
+		pq.Array(movie.Genres),
+		movie.ID,
+	}
+
+	// Use the QueryRow() method to execute the query, passing in the args slice as a variadic parameter and scanning the new version value into the movie struct.
+	return m.DB.QueryRow(query, args...).Scan(&movie.Version)
 }
 
 // Delete : Deleting a specific record from the movies table