Getting data to share in tables

Question

I am trying to create a movie springboot application and I am trying to get my Genre table to populate in my movies table. I am having errors with mismatch type.

@PostMapping("/movies/{movie_id}/genre")
@ResponseStatus(code = HttpStatus.CREATED)
public GenresData insertGenres(@PathVariable Long movie_id, 
        @RequestBody GenresData genresData) {
    log.info("Creating genre {} for movies with ID={}", movie_id, 
            genresData);
    return moviesService.saveGenres(movie_id, genresData);

}}

for(Movies movie : genres.getMovies()) {
        movies.add(new MoviesData(movie));
    }

What I am trying to do is when I do a POST request to add data to genres to show up in the movies table.