Domain layer

The domain layer defines the core business rules of Cinemapedia through entities, abstract datasources, and repository contracts.

The domain layer is the innermost ring of the architecture. It contains no framework imports and no knowledge of how data is fetched or displayed. Everything else depends on it.

Structure

lib/domain/
├── entities/
│   └── movie.dart
├── datasources/
│   └── movies_datasource.dart
└── repositories/
    └── movies_repository.dart

The Movie entity

Movie is the canonical representation of a film throughout the application. It is a plain Dart class with no serialization logic or external dependencies.

class Movie {
  final bool adult;
  final String backdropPath;
  final List<int> genreIds;
  final int id;
  final String originalLanguage;
  final String originalTitle;
  final String overview;
  final double popularity;
  final String posterPath;
  final DateTime releaseDate;
  final String title;
  final bool video;
  final double voteAverage;
  final int voteCount;

  Movie({
    required this.adult,
    required this.backdropPath,
    required this.genreIds,
    required this.id,
    required this.originalLanguage,
    required this.originalTitle,
    required this.overview,
    required this.popularity,
    required this.posterPath,
    required this.releaseDate,
    required this.title,
    required this.video,
    required this.voteAverage,
    required this.voteCount,
  });
}

Field reference

Field	Type	Description
id	int	Unique TheMovieDB identifier
title	String	Localized movie title
originalTitle	String	Title in the original language
overview	String	Plot summary
posterPath	String	Full URL to the poster image
backdropPath	String	Full URL to the backdrop image
releaseDate	DateTime	Theatrical release date
voteAverage	double	Average user rating (0–10)
voteCount	int	Total number of ratings
popularity	double	TheMovieDB popularity score
genreIds	List<int>	Genre identifiers
originalLanguage	String	ISO 639-1 language code
adult	bool	Whether the film is adult-rated
video	bool	Whether a video clip is available

posterPath and backdropPath on the domain entity are already full URLs. The infrastructure mapper is responsible for constructing them — the domain entity never knows about the image CDN.

Abstract datasource

MoviesDatasource is an abstract class that declares what operations any data source must support. The domain defines the contract; the infrastructure fulfills it.

import 'package:cinemapedia_220083/domain/entities/movie.dart';

abstract class MoviesDatasource {
  Future<List<Movie>> getNowPlaying({int page = 1});
  Future<List<Movie>> getPopular({int page = 1});
  Future<List<Movie>> getUpcoming({int page = 1});
  Future<List<Movie>> getTopRated({int page = 1});
  Future<List<Movie>> getMexicanMovies({int page = 1});
}

All methods accept a page parameter that defaults to 1, enabling pagination without forcing callers to supply it.

Abstract repository

MoviesRepository mirrors the datasource contract. The extra abstraction layer allows the application to swap datasources or add caching inside a repository implementation without changing the presentation layer.

import 'package:cinemapedia_220083/domain/entities/movie.dart';

abstract class MoviesRepository {
  Future<List<Movie>> getNowPlaying({int page = 1});
  Future<List<Movie>> getPopular({int page = 1});
  Future<List<Movie>> getUpcoming({int page = 1});
  Future<List<Movie>> getTopRated({int page = 1});
  Future<List<Movie>> getMexicanMovies({int page = 1});
}

The repository and datasource abstractions look identical here, but they serve different purposes. The datasource is about raw data access; the repository is where business logic (caching, merging sources, error handling) would live as the app grows.