c# - MongoDB - 在单个集合中插入多种类型的对象

Question

我有不同类的对象，想将它们存储在 MongoDB 中的单个集合中。

我将 asp.net core 2.2 与 MongoDB.Driver 2.8.0 和 MongoDB 4.0.5 一起使用。我做了一些尝试。

想法:我可以将以下所有对象存储在一个集合中。目前我可以保存它们，但我无法阅读它们 -> 获取“FormatException:元素‘_id’不匹配类 Mongo2.Models.MongoEntity 的任何字段或属性。” 但仅在重新运行应用程序之后。在空数据库上，我可以保存对象并检索它们。当我关闭应用程序并且不删除数据库时， collection.Find(book => true).ToList(); 出现异常
}

我想我遗漏了一些步骤或者我的方法无效 - 在互联网上找不到任何可行的示例。

任何帮助将不胜感激。通过共享工作解决方案/示例的链接或在此处。

型号:

public class MongoEntity
{
}

[BsonIgnoreExtraElements]
public class BookLibrary : MongoEntity
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string BookLibraryId { get; set; }
    public List<Book> Library { get; set; }
}

[BsonIgnoreExtraElements]
public class Book : MongoEntity
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string BookId { get; set; }

    [BsonElement("Name")]
    public string BookName { get; set; }

    [BsonElement("Price")]
    public decimal Price { get; set; }

    [BsonElement("Category")]
    public Category Category { get; set; }

    [BsonElement("Author")]
    public Author Author { get; set; }

    [BsonElement("Date")]
    public DateTime Added { get; set; }
}

[BsonIgnoreExtraElements]
public class Author : MongoEntity
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string AuthorId { get; set; }
    [BsonElement("Author name")]
    public string Name { get; set; }
    [BsonElement("Author last name")]
    public string LastName { get; set; }
}

[BsonIgnoreExtraElements]
public class Category : MongoEntity
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string CategoryId { get; set; }
    [BsonElement("Category name")]
    public string CategoryName { get; set; }
}

数据上下文:

public class BookContext
{
    private readonly IMongoDatabase _database;
    private readonly IMongoClient _client;

    public BookContext(IConfiguration configuration)
    {
        _client = new MongoClient(configuration.GetSection(nameof(MongoDbSettings)).Get<MongoDbSettings>().ConnectionString);
        _database = _client.GetDatabase(configuration.GetSection(nameof(MongoDbSettings)).Get<MongoDbSettings>().DatabaseName);

    }

    public List<MongoEntity> Get()
    {
        var collection = _database.GetCollection<MongoEntity>("Books");
        return collection.Find(book => true).ToList();
    }

    public void AddBsonDocument()
    {
        var author = new Author()
        {
            Name = "Name",
            LastName = "Lastname",
            AuthorId = ObjectId.GenerateNewId().ToString()
        };

        var category = new Category()
        {
            CategoryId = ObjectId.GenerateNewId().ToString(),
            CategoryName = "Non-fiction"
        };

        var book = new Book()
        {
            BookName = "Random title",
            Category = category,
            Price = 54.93m,
            Added = DateTime.Now,
            BookId = ObjectId.GenerateNewId().ToString(),
            Author = author
        };

        var lib = new BookLibrary(){BookLibraryId = ObjectId.GenerateNewId().ToString(), Library = new List<Book>()};
        lib.Library.Add(book);



        var collection = _database.GetCollection<MongoEntity>("Books");

        var list = new List<MongoEntity> {lib, book, author, category};

        collection.InsertMany(list);

    }
}

Answer 1

结果证明答案非常简单明了，但不知何故我错过了。

对象的类型与集合名称没有很强的相关性，所以我可以使用:

var books = _database.GetCollection<Books>("Books");
var bookLibraries = _database.GetCollection<BookLibrary>("Books");
var authors = _database.GetCollection<Author>("Books");
var categories = _database.GetCollection<Category>("Books");

另一种解决方案是使用 BsonDocument 类型:

var books = _database.GetCollection<BsonDocument>("Books");

就是这样。