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The infrastructure layer is where external concerns live: HTTP clients, JSON models, and data transformation. It implements every abstract class defined in the domain.

​
Structure

lib/infrastructure/
├── datasources/
│   └── moviedb_datasource.dart
├── mappers/
│   └── movie_mapper.dart
├── models/
│   └── moviedb/
│       ├── movie_moviedb.dart
│       └── moviedb_response.dart
└── repositories/
    └── movie_repository_impl.dart

​
Concrete datasource

MoviedbDataSource implements MoviesDatasource using Dio as the HTTP client. It is configured once at construction time with the base URL, API key, and language. 
class MoviedbDataSource extends MoviesDatasource {
  final Dio dio = Dio(
    BaseOptions(
      baseUrl: 'https://api.themoviedb.org/3',
      queryParameters: {
        'api_key': Environment.theMovieDbKey,
        'language': 'es-MX',
      },
    ),
  );

  @override
  Future<List<Movie>> getNowPlaying({int page = 1}) async {
    final response = await dio.get(
      '/movie/now_playing',
      queryParameters: {'page': page},
    );

    final movieDBResponse = MovieDbResponse.fromJson(response.data);

    final List<Movie> movies = movieDBResponse.results
        .where((moviedb) => moviedb.posterPath != 'no-poster')
        .map((moviedb) => MovieMapper.movieDBToEntity(moviedb))
        .toList();

    return movies;
  }

  // ... getPopular, getUpcoming, getTopRated follow the same pattern
}
Every method follows the same three-step pattern:
  1. Make a GET request with the page number
  2. Deserialize the response into MovieDbResponse
  3. Filter out movies with no poster, then map each to a domain Movie

​
Mexican movies endpoint

The getMexicanMovies method uses the /discover/movie endpoint with additional filters: 
@override
Future<List<Movie>> getMexicanMovies({int page = 1}) async {
  final response = await dio.get(
    '/discover/movie',
    queryParameters: {
      'page': page,
      'region': 'MX',
      'withOriginalLanguaje': 'es',
      'with_origin_country': 'MX',
      'sort_by': 'vote_average.desc',
      'vote_count.gte': 10,
    },
  );

  final movieDBResponse = MovieDbResponse.fromJson(response.data);

  final List<Movie> movies = movieDBResponse.results
      .where((moviedb) => moviedb.posterPath != 'no-poster')
      .map((moviedb) => MovieMapper.movieDBToEntity(moviedb))
      .toList();

  return movies;
}

​
API response models

​
MovieDbResponse

Represents the top-level JSON envelope returned by TheMovieDB list endpoints. 
class MovieDbResponse {
  final Dates? dates;
  final int page;
  final List<MovieMovieDB> results;
  final int totalPages;
  final int totalResults;

  factory MovieDbResponse.fromJson(Map<String, dynamic> json) =>
      MovieDbResponse(
        dates: json["dates"] != null ? Dates.fromJson(json["dates"]) : null,
        page: json["page"],
        results: List<MovieMovieDB>.from(
          json["results"].map((x) => MovieMovieDB.fromJson(x)),
        ),
        totalPages: json["total_pages"],
        totalResults: json["total_results"],
      );
}

​
MovieMovieDB

Maps the per-film JSON object from the API. The fromJson factory applies safe defaults for nullable fields: 
factory MovieMovieDB.fromJson(Map<String, dynamic> json) => MovieMovieDB(
  adult: json["adult"] ?? false,
  backdropPath: json["backdrop_path"] ?? '',
  genreIds: List<int>.from(json["genre_ids"].map((x) => x)),
  id: json["id"],
  originalLanguage: json["original_language"],
  originalTitle: json["original_title"],
  overview: json["overview"] ?? '',
  popularity: json["popularity"]?.toDouble(),
  posterPath: json["poster_path"] ?? '',
  releaseDate:
      (json["release_date"] != null &&
          json["release_date"].toString().isNotEmpty)
      ? DateTime.tryParse(json["release_date"]) ?? DateTime(1900)
      : DateTime(1900),
  title: json["title"],
  video: json["video"],
  voteAverage: json["vote_average"]?.toDouble(),
  voteCount: json["vote_count"],
);
releaseDate defaults to DateTime(1900) when the API returns a null or empty string rather than throwing a parse error.

​
Mapper

MovieMapper is a stateless utility class with a single static method that converts a MovieMovieDB model into a domain Movie entity. 
class MovieMapper {
  static Movie movieDBToEntity(MovieMovieDB moviedb) => Movie(
    adult: moviedb.adult,
    backdropPath: (moviedb.backdropPath != '')
        ? 'http://image.tmdb.org/t/p/w500${moviedb.backdropPath}'
        : 'https://sd.keepcalms.com/i-w600/keep-calm-poster-not-found.jpg',
    genreIds: moviedb.genreIds,
    id: moviedb.id,
    originalLanguage: moviedb.originalLanguage,
    originalTitle: moviedb.originalTitle,
    overview: moviedb.overview,
    popularity: moviedb.popularity,
    posterPath: (moviedb.posterPath != '')
        ? 'http://image.tmdb.org/t/p/w500${moviedb.posterPath}'
        : 'no-poster',
    releaseDate: moviedb.releaseDate,
    title: moviedb.title,
    video: moviedb.video,
    voteAverage: moviedb.voteAverage,
    voteCount: moviedb.voteCount,
  );
}
Key transformations applied by the mapper:
  • backdropPath — prepends the TMDB image CDN base URL (http://image.tmdb.org/t/p/w500); falls back to a placeholder image if the path is empty
  • posterPath — same CDN construction; returns the string 'no-poster' when empty (the datasource later filters these out)
  • All other fields pass through unchanged

​
Repository implementation

MovieRepositoryImpl implements MoviesRepository by delegating every call directly to the injected datasource. It decouples the presentation layer from any specific datasource. 
class MovieRepositoryImpl implements MoviesRepository {
  final MoviesDatasource datasource;

  MovieRepositoryImpl(this.datasource);

  @override
  Future<List<Movie>> getNowPlaying({int page = 1}) {
    return datasource.getNowPlaying(page: page);
  }

  @override
  Future<List<Movie>> getPopular({int page = 1}) {
    return datasource.getPopular(page: page);
  }

  @override
  Future<List<Movie>> getUpcoming({int page = 1}) {
    return datasource.getUpcoming(page: page);
  }

  @override
  Future<List<Movie>> getTopRated({int page = 1}) {
    return datasource.getTopRated(page: page);
  }

  @override
  Future<List<Movie>> getMexicanMovies({int page = 1}) {
    return datasource.getMexicanMovies(page: page);
  }
}
Because MovieRepositoryImpl accepts any MoviesDatasource, swapping MoviedbDataSource for a local cache or a mock in tests requires changing only the constructor call at the provider level.

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