我无法从数据库中获取.NET 7.0 Web API上的推文回复。

huangapple
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英文:

I can't get Tweet Replies from database on my .NET 7.0 Web API

问题

我正在制作一个Twitter克隆API。当我尝试通过ID获取带有回复的推文时，即使有回复，它也返回null。

Tweet.cs

  1. using TwitterCloneApp.Core.Interfaces;
  3. namespace TwitterCloneApp.Core.Models
  4. {
  5.     public class Tweet : IBaseEntity, IDeletable, IUpdatedAt, ICreatedAt
  6. 	{
  7. 		public int Id { get; set; }
  8. 		public int UserId { get; set; }
  9. 		public string Content { get; set; }
  10. 		public User User { get; set; }
  11. 		public bool isMainTweet { get; set; }
  12. 		public bool IsDeleted { get; set; } = false;
  13.         public DateTime? DeletedAt { get; set; }
  14. 		public DateTime? UpdatedAt { get; set; }
  15. 		public DateTime? CreatedAt { get; set; }
  16.         public ICollection<Tag>? Tags { get; set; } // Many-to-Many ilişkisi için koleksiyon
  17. 		public ICollection<Tweet>? Replies { get; set; }
  18. 		public ICollection<Like>? Likes { get; set; }
  19.     }
  20. }

TwReply.Cs（用于关系）

  1. namespace TwitterCloneApp.Core.Models
  2. {
  3.     public class TwReply
  4.     {
  5.         public int TweetId { get; set; }
  6.         public int ReplyId { get; set; }
  7.         public Tweet Tweet { get; set; }
  8.         public Tweet Reply { get; set; }
  9.     }
  10. }

TweetDto.cs

  1. using TwitterCloneApp.DTO.Tag;
  2. using TwitterCloneApp.DTO.User;
  4. namespace TwitterCloneApp.DTO.Tweet
  5. {
  6.     public class TweetDto
  7. 	{
  8.         public int Id { get; set; }
  9. 		public UserResponseDto User { get; set; }
  10. 		public string? Content { get; set; }
  11.         public DateTime? CreatedAt { get; set; }
  12.         public int LikeCount { get; set; }
  13. 		public List<TagResponseDto>? Tags { get; set; }
  14.         public List<ReplyResponseDto>? Replies { get; set; }
  15.     }
  16. }

ReplyResponseDto.cs

  1. using TwitterCloneApp.DTO.User;
  3. namespace TwitterCloneApp.DTO.Tweet
  4. {
  5.     public class ReplyResponseDto
  6.     {
  7.         public UserResponseDto User { get; set; }
  8.         public string Content { get; set; }
  9.         public DateTime? CreatedAt { get; set; }
  10.         public int LikeCount { get; set; }
  11.     }
  12. }

UserResponseDto.cs

  1. namespace TwitterCloneApp.DTO.User
  2. {
  3. 	public class UserResponseDto
  4. 	{
  5.         public string UserName { get; set; }
  6.         public string DisplayName { get; set; }
  7.         public string? ProfileImg { get; set; }
  8.     }
  9. }

TweetController部分

  1. [HttpGet("[action]")]
  2. public async Task<IActionResult> GetTweetByIdAsync(int id)
  3. {
  4. 	var tweet = await _tweetService.GetTweetByIdAsync(id);
  5. 	return Ok(tweet);
  6. }

TweetService部分

  1. public async Task<TweetDto> GetTweetByIdAsync(int tweetId)
  2. {
  3. 	return await _tweetRepository.GetTweetWithTagsByIdAsync(tweetId);
  4. }

TweetRepository部分

  1. public async Task<TweetDto> GetTweetWithTagsByIdAsync(int tweetId)
  2. {
  3. 	var tweet = await _tweet.Include(t => t.Tags)
  4. 							.Include(t => t.Replies).ThenInclude(reply => reply.User)
  5. 							.Include(t => t.User)
  6. 							.Include(t => t.Likes)
  7. 							.FirstOrDefaultAsync(t => t.Id == tweetId);
  9. 	if (tweet == null)
  10. 	{
  11. 		return null; // 或者执行必要的操作
  12. 	}
  14. 	var tweetDto = new TweetDto
  15. 	{
  16. 		Id = tweet.Id,
  17. 		Content = tweet.Content,
  18. 		CreatedAt = tweet.CreatedAt,
  19. 		LikeCount = tweet.Likes?.Count ?? 0,
  20. 		Tags = tweet.Tags?.Select(t => new TagResponseDto
  21. 		{
  22. 			Name = t.Name
  23. 		}).ToList(),
  24. 		User = new UserResponseDto
  25. 		{
  26. 			UserName = tweet.User.UserName,
  27. 			DisplayName = tweet.User.DisplayName,
  28. 			ProfileImg = tweet.User.ProfileImg
  29. 		},
  30. 		Replies = tweet.Replies?.Select(reply => new ReplyResponseDto
  31. 		{
  32. 			User = new UserResponseDto
  33. 			{
  34. 				UserName = reply.User.UserName,
  35. 				DisplayName = reply.User.DisplayName,
  36. 				ProfileImg = reply.User.ProfileImg
  37. 			},
  38. 			Content = reply.Content,
  39. 			CreatedAt = reply.CreatedAt,
  40. 			LikeCount = reply.Likes?.Count ?? 0
  41. 		}).ToList()
  42. 	};
  44. 	return tweetDto;
  45. }

AppDbContext.cs

  1. using Microsoft.EntityFrameworkCore;
  2. using System.Reflection;
  3. using TwitterCloneApp.Core.Models;
  5. namespace TwitterCloneApp.Repository
  6. {
  7.     public class AppDbContext : DbContext
  8.     {
  9.         public AppDbContext(DbContextOptions<AppDbContext> options) : base(options)
  10.         { 
  11.         }
  12.         public DbSet<User> Users { get; set; }
  13.         public DbSet<Tweet> Tweets { get; set; }
  14.         public DbSet<Tag> Tags { get; set; }
  15.         public DbSet<Like> Likes { get; set; }
  16.         public DbSet<TwReply> TwReplies { get; set; }
  18.         protected override void OnModelCreating(ModelBuilder modelBuilder)
  19.         {
  20.             modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
  21.             
  22.             var relationships = modelBuilder.Model.GetEntityTypes()
  23.                 .SelectMany(e => e.GetForeignKeys());
  25.             foreach (var relationship in relationships)
  26.             {
  27.                 relationship.DeleteBehavior = DeleteBehavior.Restrict;
  28.             }
  29.             base.OnModelCreating(modelBuilder);
  30.         }
  32.     }
  33. }

推文ID为1有2个回复（3和10），但输出为：

  1. {
  2.   "id": 1,
  3.   "user": {
  4.     "userName": "asdasdasd",
  5.     "displayName": "asdasdasd",
  6.     "profileImg": "string"
  7.   },
  8.   "content": "First tweet",
  9.   "createdAt": null,
  10.   "likeCount": 3,
  11.   "tags": [
  12.     {
  13.       "name": "#testingSeed1"
  14.     },
  15.     {
  16.       "name": "#testingSeed2"
  17.     },
  18.     {
  19.       "name": "#testing"
  20.     }
  21.   ],
  22.   "replies": []
  23. }

我尝试在获取推文时获取回复，但程序不会获取回复。我使用的是Entity Framework Core。

英文:

I am making a Twitter Clone API. When I try to get a Tweet by Id with its replies, it returns null even if there is a reply.
Tweet.cs

  1. using TwitterCloneApp.Core.Interfaces;
  3. namespace TwitterCloneApp.Core.Models
  4. {
  5.     public class Tweet : IBaseEntity, IDeletable, IUpdatedAt, ICreatedAt
  6. 	{
  7. 		public int Id { get; set; }
  8. 		public int UserId { get; set; }
  9. 		public string Content { get; set; }
  10. 		public User User { get; set; }
  11. 		public bool isMainTweet { get; set; }
  12. 		public bool IsDeleted { get; set; } = false;
  13.         public DateTime? DeletedAt { get; set; }
  14. 		public DateTime? UpdatedAt { get; set; }
  15. 		public DateTime? CreatedAt { get; set; }
  16.         public ICollection&lt;Tag&gt;? Tags { get; set; } // Many-to-Many ilişkisi i&#231;in koleksiyon
  17. 		public ICollection&lt;Tweet&gt;? Replies { get; set; }
  18. 		public ICollection&lt;Like&gt;? Likes { get; set; }
  19.     }
  20. }

TwReply.Cs (for relation)

  1. namespace TwitterCloneApp.Core.Models
  2. {
  3.     public class TwReply
  4.     {
  5.         public int TweetId { get; set; }
  6.         public int ReplyId { get; set; }
  7.         public Tweet Tweet { get; set; }
  8.         public Tweet Reply { get; set; }
  9.     }
  10. }

TweetDto.cs

  1. using TwitterCloneApp.DTO.Tag;
  2. using TwitterCloneApp.DTO.User;
  4. namespace TwitterCloneApp.DTO.Tweet
  5. {
  6.     public class TweetDto
  7. 	{
  8.         public int Id { get; set; }
  9. 		public UserResponseDto User { get; set; }
  10. 		public string? Content { get; set; }
  11.         public DateTime? CreatedAt { get; set; }
  12.         public int LikeCount { get; set; }
  13. 		public List&lt;TagResponseDto&gt;? Tags { get; set; }
  14.         public List&lt;ReplyResponseDto&gt;? Replies { get; set; }
  15.     }
  16. }

ReplyResponseDto.cs

  1. using TwitterCloneApp.DTO.User;
  3. namespace TwitterCloneApp.DTO.Tweet
  4. {
  5.     public class ReplyResponseDto
  6.     {
  7.         public UserResponseDto User { get; set; }
  8.         public string Content { get; set; }
  9.         public DateTime? CreatedAt { get; set; }
  10.         public int LikeCount { get; set; }
  11.     }
  12. }

UserResponseDto.cs

  1. namespace TwitterCloneApp.DTO.User
  2. {
  3. 	public class UserResponseDto
  4. 	{
  5.         public string UserName { get; set; }
  6.         public string DisplayName { get; set; }
  7.         public string? ProfileImg { get; set; }
  8.     }
  9. }

TweetController part

  1. [HttpGet(&quot;[action]&quot;)]
  2. public async Task&lt;IActionResult&gt; GetTweetByIdAsync(int id)
  3. {
  4. 	var tweet = await _tweetService.GetTweetByIdAsync(id);
  5. 	return Ok(tweet);
  6. }

TweetService part

  1. public async Task&lt;TweetDto&gt; GetTweetByIdAsync(int tweetId)
  2. {
  3. 	return await _tweetRepository.GetTweetWithTagsByIdAsync(tweetId);
  4. }

TweetRepository part

  1. public async Task&lt;TweetDto&gt; GetTweetWithTagsByIdAsync(int tweetId)
  2. {
  3. 	var tweet = await _tweet.Include(t =&gt; t.Tags)
  4. 							.Include(t =&gt; t.Replies).ThenInclude(reply =&gt; reply.User)
  5. 							.Include(t =&gt; t.User)
  6. 							.Include(t =&gt; t.Likes)
  7. 							.FirstOrDefaultAsync(t =&gt; t.Id == tweetId);
  9. 	if (tweet == null)
  10. 	{
  11. 		return null; // veya gerekli işlemleri yapın
  12. 	}
  14. 	var tweetDto = new TweetDto
  15. 	{
  16. 		Id = tweet.Id,
  17. 		Content = tweet.Content,
  18. 		CreatedAt = tweet.CreatedAt,
  19. 		LikeCount = tweet.Likes?.Count ?? 0,
  20. 		Tags = tweet.Tags?.Select(t =&gt; new TagResponseDto
  21. 		{
  22. 			Name = t.Name
  23. 		}).ToList(),
  24. 		User = new UserResponseDto
  25. 		{
  26. 			UserName = tweet.User.UserName,
  27. 			DisplayName = tweet.User.DisplayName,
  28. 			ProfileImg = tweet.User.ProfileImg
  29. 		},
  30. 		Replies = tweet.Replies?.Select(reply =&gt; new ReplyResponseDto
  31. 		{
  32. 			User = new UserResponseDto
  33. 			{
  34. 				UserName = reply.User.UserName,
  35. 				DisplayName = reply.User.DisplayName,
  36. 				ProfileImg = reply.User.ProfileImg
  37. 			},
  38. 			Content = reply.Content,
  39. 			CreatedAt = reply.CreatedAt,
  40. 			LikeCount = reply.Likes?.Count ?? 0
  41. 		}).ToList()
  42. 	};
  44. 	return tweetDto;
  45. }

AppDbContext.cs

  1. using Microsoft.EntityFrameworkCore;
  2. using System.Reflection;
  3. using TwitterCloneApp.Core.Models;
  5. namespace TwitterCloneApp.Repository
  6. {
  7.     public class AppDbContext : DbContext
  8.     {
  9.         public AppDbContext(DbContextOptions&lt;AppDbContext&gt; options) : base(options)
  10.         { 
  11.         }
  12.         public DbSet&lt;User&gt; Users { get; set; }
  13.         public DbSet&lt;Tweet&gt; Tweets { get; set; }
  14.         public DbSet&lt;Tag&gt; Tags { get; set; }
  15.         public DbSet&lt;Like&gt; Likes { get; set; }
  16.         public DbSet&lt;TwReply&gt; TwReplies { get; set; }
  18.         protected override void OnModelCreating(ModelBuilder modelBuilder)
  19.         {
  20.             modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
  21.             
  22.             var relationships = modelBuilder.Model.GetEntityTypes()
  23.                 .SelectMany(e =&gt; e.GetForeignKeys());
  25.             foreach (var relationship in relationships)
  26.             {
  27.                 relationship.DeleteBehavior = DeleteBehavior.Restrict;
  28.             }
  29.             base.OnModelCreating(modelBuilder);
  30.         }
  32.     }
  33. }

There are 2 replies (3 and 10) for Tweet Id:1
but output is:

  1. {
  2.   &quot;id&quot;: 1,
  3.   &quot;user&quot;: {
  4.     &quot;userName&quot;: &quot;asdasdasd&quot;,
  5.     &quot;displayName&quot;: &quot;asdasdasd&quot;,
  6.     &quot;profileImg&quot;: &quot;string&quot;
  7.   },
  8.   &quot;content&quot;: &quot;First tweet&quot;,
  9.   &quot;createdAt&quot;: null,
  10.   &quot;likeCount&quot;: 3,
  11.   &quot;tags&quot;: [
  12.     {
  13.       &quot;name&quot;: &quot;#testingSeed1&quot;
  14.     },
  15.     {
  16.       &quot;name&quot;: &quot;#testingSeed2&quot;
  17.     },
  18.     {
  19.       &quot;name&quot;: &quot;#testing&quot;
  20.     }
  21.   ],
  22.   &quot;replies&quot;: []
  23. }

我无法从数据库中获取.NET 7.0 Web API上的推文回复。

我无法从数据库中获取.NET 7.0 Web API上的推文回复。

I tried to get replies while getting a Tweet by Id but the program doesn't get Replies. I checked how does it work with breakpoints and it seems problem is in TweetRepository part. It returns nothing for Replies when it gets entity. I use Entity Framework Core BTW.

答案1

得分: 1

实体Tweet（简化版）如下所示：

  1. public class Tweet
  2. {
  3.     public int Id { get; set; }
  4.     public string Content { get; set; } = "";
  5.     public ICollection<Tweet>? Replies { get; set; }
  6. }

然后，EF Core 将把这个模型映射到以下数据库模式：

  1. CREATE TABLE [Tweets] (
  2.     [Id] int NOT NULL,
  3.     [Content] nvarchar(max) NOT NULL,
  4.     [TweetId] int NULL,
  5.     CONSTRAINT [PK_Tweets] PRIMARY KEY ([Id]),
  6.     CONSTRAINT [FK_Tweets_Tweets_TweetId] FOREIGN KEY ([TweetId]) REFERENCES [Tweets] ([Id])
  7. );

当没有指定数据库模式时，EF Core 使用约定来确定数据库模式。对于指向同一实体的集合导航属性，约定是一对多关系（一个推文可以有多个回复，但只能回复一个推文）。就像模型是这样的：

  1. public class Tweet
  2. {
  3.     public int Id { get; set; }
  4.     public string Content { get; set; } = "";
  5.     public ICollection<Tweet>? Replies { get; set; }
  6.     public Tweet ReplyTo { get; set; }
  7. }

您可以参考文档 EF Core：关系发现的约定 了解更多关于关系的约定信息。

在您的情况下，这是一个多对多关系（一个推文可以有多个回复，也可以回复多个推文），通过中间实体 TwReply。

按照约定，模型将如下所示：

  1. public class Tweet
  2. {
  3.     public int Id { get; set; }
  4.     public string Content { get; set; } = "";
  5.     public ICollection<TwReply>? Replies { get; set; }
  6. }
  8. public class TwReply
  9. {
  10.     public int Id { get; set; }
  11.     public Tweet Tweet { get; set; }
  12.     public Tweet Reply { get; set; }
  13. }

如果您想保留您的模型，您需要手动指定关系，如下所示：

  1. protected override void OnModelCreating(ModelBuilder modelBuilder)
  2. {
  3.     ...
  4.     modelBuilder.Entity<Tweet>()
  5.         .HasMany(t => t.Replies)
  6.         .WithMany()
  7.         .UsingEntity<TwReply>(
  8.             i => i.HasOne(tr => tr.Reply).WithMany(),
  9.             i => i.HasOne(tr => tr.Tweet).WithMany()
  10.         );
  11. }
英文:

The entity Tweet (simplified) is :

  1. public class Tweet
  2. {
  3.     public int Id { get; set; }
  4.     public string Content { get; set; } = &quot;&quot;;
  5.     public ICollection&lt;Tweet&gt;? Replies { get; set; }
  6. }

Then EF Core will tanlaste this model to this DB Schema :

  1. CREATE TABLE [Tweets] (
  2.     [Id] int NOT NULL,
  3.     [Content] nvarchar(max) NOT NULL,
  4.     [TweetId] int NULL,
  5.     CONSTRAINT [PK_Tweets] PRIMARY KEY ([Id]),
  6.     CONSTRAINT [FK_Tweets_Tweets_TweetId] FOREIGN KEY ([TweetId]) REFERENCES [Tweets] ([Id])
  7. );

When the DB schema isn't specified, EF Core use convention to determine the DB schema. And the convention for a collection navigation property to the same entity is 1 to n (a tweet can have manyreplies, but can reply to only one tweet). It's like the model was :

  1. public class Tweet
  2. {
  3.     public int Id { get; set; }
  4.     public string Content { get; set; } = &quot;&quot;;
  5.     public ICollection&lt;Tweet&gt;? Replies { get; set; }
  6.     public Tweet ReplyTo { get; set; }
  7. }

You can refer to the documentatino EF Core : Conventions for relationship discovery for more information about the convention about relationship.

In you case, it's a relation n to n (a tweet can have many reply and can reply to many tweet) by the intermediate entity TwReply.

By convention, the model will be :

  1. public class Tweet
  2. {
  3.     public int Id { get; set; }
  4.     public string Content { get; set; } = &quot;&quot;;
  5.     public ICollection&lt;TwReply&gt;? Replies { get; set; }
  6. }
  8. public class TwReply
  9. {
  10.     public int Id { get; set; }
  11.     public Tweet Tweet { get; set; }
  12.     public Tweet Reply { get; set; }
  13. }

If you want keep your model, you need to specify manually the relation like :

  1. protected override void OnModelCreating(ModelBuilder modelBuilder)
  2. {
  3.     ...
  4.     modelBuilder.Entity&lt;Tweet&gt;()
  5.         .HasMany(t =&gt; t.Replies)
  6.         .WithMany()
  7.         .UsingEntity&lt;TwReply&gt;(
  8.             i =&gt; i.HasOne(tr =&gt; tr.Reply).WithMany(),
  9.             i =&gt; i.HasOne(tr =&gt; tr.Tweet).WithMany()
  10.         );
  11. }

huangapple
  • 本文由 发表于 2023年7月27日 17:14:01
  • 转载请务必保留本文链接：https://go.coder-hub.com/76778218.html
  • .net
  • c#
  • entity-framework-core
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