LiteDb - 查找具有 id 属于列表一部分的子文档的所有文档

Question

这是我的对象模型：

    class PhoneBookCategory
    {
        public Guid Id { get; set; }
        public List<PhoneBook> PhoneBooks { get; set; }
    }

    class PhoneBook
    {
        public Guid Id { get; set; }
    }

我正在寻找的是“所有具有 ID 位于列表中的电话簿的 PhoneBookCategories”。或者，在 Linq 语法中

    List<Guid> myList = [Guid.NewGuid(), Guid.NewGuid()];
    GetCollection<PhoneBookCategory>()
       .Find(u => u.PhoneBooks.Any(x => myList.Contains(x.Id));

LiteDB 的 Linq 解析器无法处理这个问题，所以我尝试使用查询语法并最终得到这里：

    var bsArray = new BsonArray();
    myList.Foreach(u => bsArray.Add(u));
    GetCollection<PhoneBookCategory>().Query()
       .Where(Query.In("$.PhoneBooks[*].Id ALL", bsArray))).ToList();

但让我感动的是这个

    GetCollection<PhoneBookCategory>()
       .Find(u => u.PhoneBooks == null || u.PhoneBooks.Count == 0)

相反。如果我用

ALL

替换

ANY

，我最终不会得到任何结果。

Answer 1

你可以这样尝试。

我创建了一个简单的存储库来集中功能和一个测试方法来测试结果。

    public class PhoneBookRepository
    {
      private ConnectionString _connectionString;
    
          private const string _categories_Collection = "categories";
          private const string _phoneBooks_Collection = "phoneBooks";
    
          public PhoneBookRepository(string fileName)
          {
              _connectionString = new ConnectionString(fileName);
          }
    

 public List<PhoneBookCategory> GetPhoneBookCategoriesFromPhoneBook(PhoneBook phoneBook)
          {
              using (var db = new LiteDatabase(_connectionString))
              {
                  var _categoryCollection = db.GetCollection<PhoneBookCategory>(_categories_Collection);
    
                  var categories = _categoryCollection.Find(c => c.PhoneBooks.Select(pb => pb.Id).Contains(phoneBook.Id)).ToList();
    
                  return categories;
              }
          }

          public void AddPhonebook(PhoneBook pb)
          {
              using (var db = new LiteDatabase(_connectionString))
              {
                  db.BeginTrans();
    
                  var _collection = db.GetCollection<PhoneBook>(_phoneBooks_Collection);
    
                  _collection.Insert(pb);
    
                  db.Commit();
              }
          }
    
          public void AddPhoneBookCategories(PhoneBookCategory pbc)
          {
              using (var db = new LiteDatabase(_connectionString))
              {
                  db.BeginTrans();
    
                  var _collection = db.GetCollection<PhoneBookCategory>(_categories_Collection);
    
                  _collection.Insert(pbc);
    
                  db.Commit();
              }
          }
    
         
      }

这是带有测试方法的测试类：

  [TestClass]
  public class LitedbPhoneBookTest
  {
      [TestMethod]
      public void CanGetPhoneBookCategories()
      {
          var pb1 = new PhoneBook()
          {
              Id = Guid.NewGuid(),
          };

          var pb2 = new PhoneBook()
          {
              Id = Guid.NewGuid(),
          };

          var pbc1 = new PhoneBookCategory() {
              Id = Guid.NewGuid(),
              PhoneBooks = new List<PhoneBook>()
              { pb1 }
          };

          var pbc2 = new PhoneBookCategory()
          {
              Id = Guid.NewGuid(),
              PhoneBooks = new List<PhoneBook>()
              { pb2 }
          };

          var pbc3 = new PhoneBookCategory()
          {
              Id = Guid.NewGuid(),
              PhoneBooks = new List<PhoneBook>()
              { pb1,pb2 }
          };

          var answerCodeRepository = new PhoneBookRepository("phoneBooks.db");

          answerCodeRepository.AddPhonebook(pb1);
          answerCodeRepository.AddPhonebook(pb2);

          answerCodeRepository.AddPhoneBookCategories(pbc1);
          answerCodeRepository.AddPhoneBookCategories(pbc2);
          answerCodeRepository.AddPhoneBookCategories(pbc3);

          var pbc1_result = answerCodeRepository.GetPhoneBookCategoriesFromPhoneBook(pb1);
          var pbc2_result = answerCodeRepository.GetPhoneBookCategoriesFromPhoneBook(pb2);

          Assert.AreEqual(2,pbc1_result.Count);
          Assert.AreEqual(2,pbc2_result.Count);
      }
  }

我希望这有帮助，请告诉我。