即使两个对象相同，C#Net.Core Object.Equals()也返回false

Question

我试图返回一个基于客户最喜欢的电影类型的推荐电影列表，而不包括那些已经是他最喜欢的。

这是我的电影对象

public class Movie
{
/// <summary>
/// Movie's title
/// </summary>
public string Title { get; set; }

/// <summary>
/// Movie's gengres list
/// </summary>
public List<string> Genres { get; set; }
private int HashCode 
{
get
{
return this.Title.GetHashCode();
}
}
/// <summary>
/// Public default constructor. Initializes an empty Movie object
/// </summary>
public Movie()
{
Genres = new List<string>();
}
/// <summary>
/// Initializes a Movie object with a given title
/// </summary>
/// <param name="title">Movie title</param>
public Movie(string title)
{
Title = title;
Genres = new List<string>();
}
/// <summary>
/// Override ToString function
/// </summary>
/// <returns>Movie's title</returns>
public override string ToString()
{
return Title;
}
public override int GetHashCode()
{
return HashCode;
}
public override bool Equals(object obj)
{
if ((obj == null) || !this.GetType().Equals(obj.GetType()))
{
return false;
}
else
{
Movie movie = (Movie)obj;
return (HashCode == movie.HashCode);
}
}
}

这是我的客户端对象

public class Client
{
/// <summary>
/// Client's First Name
/// </summary>
public string FirstName { get; set; }
/// <summary>
/// Client's Last Name
/// </summary>
public string LastName { get; set; }
/// <summary>
/// Client's full name
/// </summary>
public string FullName 
{
get
{
return $"{FirstName} {LastName}";
}
}
/// <summary>
/// Client's favorite movies
/// </summary>
public List<Movie> FavoriteMovies { get; set; }
/// <summary>
/// Public default constructor. Initializes an empty client
/// </summary>
public Client()
{
FavoriteMovies = new List<Movie>();
}
/// <summary>
/// Initializes a client object with a given name
/// </summary>
/// <param name="firstName">Client's first name</param>
/// <param name="lastName">Client's last name</param>
public Client(string firstName, string lastName)
{
FirstName = firstName;
FavoriteMovies = new List<Movie>();
}
/// <summary>
/// Initializes a client object with given name and list of favorite movies
/// </summary>
/// <param name="firstName">Client's first name</param>
/// <param name="lastName">Client's last name</param>
/// <param name="favoriteMovies">Client's list of favorite movies</param>
public Client(string firstName, string lastName, List<Movie> favoriteMovies)
{
FirstName = firstName;
LastName = lastName;
FavoriteMovies = favoriteMovies;
}
/// <summary>
/// Override ToString function that will return Client's full name
/// </summary>
/// <returns>Client's full name</returns>
public override string ToString()
{
return FullName;
}

这是我的电影列表

Movies = new List<Movie>();
Movie movie1 = new Movie("Untitled Screenplay, adapted from the book, the Price of Fame, the biography of Dennis Price. Written by Eliane Parker and Gareth Owen.");
movie1.Genres.Add("Action");
Movies.Add(movie1);
Movie movie2 = new Movie("Cannery Row");
movie2.Genres.Add("Comedy");
movie2.Genres.Add("Drama");
movie2.Genres.Add("Romance");
Movies.Add(movie2);
Movie movie3 = new Movie("Body Melt");
movie3.Genres.Add("Comedy");
movie3.Genres.Add("Horror");
movie3.Genres.Add("Sci-Fi");
Movies.Add(movie3);
Movie movie4 = new Movie("Ghost Lab");
movie4.Genres.Add("Drama");
movie4.Genres.Add("Horror");
movie4.Genres.Add("Thriller");
Movies.Add(movie4);
Movie movie5 = new Movie("Biography: WWE Legends Biography: Booker T");
movie5.Genres.Add("Action");
Movies.Add(movie5);
Movie movie6 = new Movie("Zombie Wars");
movie6.Genres.Add("Action");
Movies.Add(movie6);
Movie movie7 = new Movie("Delitto in Formula Uno");
movie7.Genres.Add("Comedy");
movie7.Genres.Add("Crime");
movie7.Genres.Add("Thriller");
Movies.Add(movie7);
Movie movie8 = new Movie("The Long and Winding Road");
movie8.Genres.Add("Comedy");
movie8.Genres.Add("Drama");
Movies.Add(movie8);

我的客户会喜欢这个

Client client2 = new Client("Belinda", "Reed");
client2.FavoriteMovies.Add(movie2);
client2.FavoriteMovies.Add(movie7);
Clients.Add(client2);

这意味着client2最喜欢的电影名为《罐头行》(即movie2(和《Uno方程式》中的《Delitto》(即《movie7》(。最喜欢的流派列表将是

"Comedy"
"Drama"
"Romance"
"Crime"
"Thriller"

返回电影推荐的功能是

public static List<Movie> MovieRecommendationsByClient(Client client, List<Movie> moviesCatalog)
{
var recommendations = moviesCatalog
.Where(movie => client.FavoriteMovies
.Any(cm => (!cm.Equals(movie)
&& cm.Genres.Intersect(movie.Genres).Any()))).ToList();

return recommendations;
}

理论上，基于客户最喜欢的电影类型列表的电影推荐，不包括他已经喜欢的电影，应该是

"Body Melt"
"Ghost Lab"
"The Long and Winding Road"

但是断言失败了，因为返回列表还包括"Cannery Row"和"Delitto in Formula Uno"

我也尝试过这种方式，得到了相同的结果：

var recommendations = from movie in moviesCatalog
from clientMovie in client.FavoriteMovies
where !clientMovie.Equals(movie) && movie.Genres.Intersect(clientMovie.Genres).Any()
group movie by movie into moviesGroup
select moviesGroup.Key;

我还尝试过比较MovieTitle属性或GetHashCode()函数，但没有成功。

当我调试测试时，我可以看到Equals(movie)返回了我期望的结果，所以我认为我在LINQ查询中做错了什么。

如有任何帮助，将不胜感激

Answer 1

首先你可以排除你已经在客户端列表中拥有的电影，然后根据类型组合进行筛选

它起作用：

var recommendations = moviesCatalog.Except(client.FavoriteMovies)
.Where(movie => client.FavoriteMovies
.Any(cm => cm.Genres.Intersect(movie.Genres).Any())).ToList();